Amino acid "little Big Bang": representing amino acid substitution matrices as dot products of Euclidian vectors.

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Zimmermann, Karel; Gibrat, Jean-François

2010-01-04

Sequence comparisons make use of a one-letter representation for amino acids, the necessary quantitative information being supplied by the substitution matrices. This paper deals with the problem of finding a representation that provides a comprehensive description of amino acid intrinsic properties consistent with the substitution matrices. We present a Euclidian vector representation of the amino acids, obtained by the singular value decomposition of the substitution matrices. The substitution matrix entries correspond to the dot product of amino acid vectors. We apply this vector encoding to the study of the relative importance of various amino acid physicochemical properties upon the substitution matrices. We also characterize and compare the PAM and BLOSUM series substitution matrices. This vector encoding introduces a Euclidian metric in the amino acid space, consistent with substitution matrices. Such a numerical description of the amino acid is useful when intrinsic properties of amino acids are necessary, for instance, building sequence profiles or finding consensus sequences, using machine learning algorithms such as Support Vector Machine and Neural Networks algorithms.

Amino acid "little Big Bang": Representing amino acid substitution matrices as dot products of Euclidian vectors

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Zimmermann Karel

2010-01-01

Full Text Available Abstract Background Sequence comparisons make use of a one-letter representation for amino acids, the necessary quantitative information being supplied by the substitution matrices. This paper deals with the problem of finding a representation that provides a comprehensive description of amino acid intrinsic properties consistent with the substitution matrices. Results We present a Euclidian vector representation of the amino acids, obtained by the singular value decomposition of the substitution matrices. The substitution matrix entries correspond to the dot product of amino acid vectors. We apply this vector encoding to the study of the relative importance of various amino acid physicochemical properties upon the substitution matrices. We also characterize and compare the PAM and BLOSUM series substitution matrices. Conclusions This vector encoding introduces a Euclidian metric in the amino acid space, consistent with substitution matrices. Such a numerical description of the amino acid is useful when intrinsic properties of amino acids are necessary, for instance, building sequence profiles or finding consensus sequences, using machine learning algorithms such as Support Vector Machine and Neural Networks algorithms.

Meta-analysis of the Effects of Insect Vector Saliva on Host Immune Responses and Infection of Vector-Transmitted Pathogens: A Focus on Leishmaniasis

OpenAIRE

Ockenfels, Brittany; Michael, Edwin; McDowell, Mary Ann

2014-01-01

A meta-analysis of the effects of vector saliva on the immune response and progression of vector-transmitted disease, specifically with regard to pathology, infection level, and host cytokine levels was conducted. Infection in the absence or presence of saliva in naïve mice was compared. In addition, infection in mice pre-exposed to uninfected vector saliva was compared to infection in unexposed mice. To control for differences in vector and pathogen species, mouse strain, and experimental de...

Mammal decline, linked to invasive Burmese python, shifts host use of vector mosquito towards reservoir hosts of a zoonotic disease.

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Hoyer, Isaiah J; Blosser, Erik M; Acevedo, Carolina; Thompson, Anna Carels; Reeves, Lawrence E; Burkett-Cadena, Nathan D

2017-10-01

Invasive apex predators have profound impacts on natural communities, yet the consequences of these impacts on the transmission of zoonotic pathogens are unexplored. Collapse of large- and medium-sized mammal populations in the Florida Everglades has been linked to the invasive Burmese python, Python bivittatus Kuhl. We used historic and current data to investigate potential impacts of these community effects on contact between the reservoir hosts (certain rodents) and vectors of Everglades virus, a zoonotic mosquito-borne pathogen that circulates in southern Florida. The percentage of blood meals taken from the primary reservoir host, the hispid cotton rat, Sigmodon hispidus Say and Ord, increased dramatically (422.2%) from 1979 (14.7%) to 2016 (76.8%), while blood meals from deer, raccoons and opossums decreased by 98.2%, reflecting precipitous declines in relative abundance of these larger mammals, attributed to python predation. Overall species diversity of hosts detected in Culex cedecei blood meals from the Everglades declined by 40.2% over the same period ( H (1979) = 1.68, H (2016) = 1.01). Predictions based upon the dilution effect theory suggest that increased relative feedings upon reservoir hosts translate into increased abundance of infectious vectors, and a corresponding upsurge of Everglades virus occurrence and risk of human exposure, although this was not tested in the current study. This work constitutes the first indication that an invasive predator can increase contact between vectors and reservoirs of a human pathogen and highlights unrecognized indirect impacts of invasive predators. © 2017 The Author(s).

Development of a gene silencing DNA vector derived from a broad host range geminivirus

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Hancock Leandria C

2009-07-01

Full Text Available Abstract Background Gene silencing is proving to be a powerful tool for genetic, developmental, and physiological analyses. The use of viral induced gene silencing (VIGS offers advantages to transgenic approaches as it can be potentially applied to non-model systems for which transgenic techniques are not readily available. However, many VIGS vectors are derived from Gemini viruses that have limited host ranges. We present a new, unipartite vector that is derived from a curtovirus that has a broad host range and will be amenable to use in many non-model systems. Results The construction of a gene silencing vector derived from the geminivirus Beet curly top virus (BCTV, named pWSRi, is reported. Two versions of the vector have been developed to allow application by biolistic techniques or by agro-infiltration. We demonstrate its ability to silence nuclear genes including ribulose bisphosphate carboxylase small subunit (rbcS, transketolase, the sulfur allele of magnesium chelatase (ChlI, and two homeotic transcription factors in spinach or tomato by generating gene-specific knock-down phenotypes. Onset of phenotypes occurred 3 to 12 weeks post-inoculation, depending on the target gene, in organs that developed after the application. The vector lacks movement genes and we found no evidence for significant spread from the site of inoculation. However, viral amplification in inoculated tissue was detected and is necessary for systemic silencing, suggesting that signals generated from active viral replicons are efficiently transported within the plant. Conclusion The unique properties of the pWSRi vector, the ability to silence genes in meristem tissue, the separation of virus and silencing phenotypes, and the broad natural host range of BCTV, suggest that it will have wide utility.

Host-agent-vector-environment measures for electronic cigarette research used in NIH grants.

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Garcia-Cazarin, Mary L; Mandal, Rachel J; Grana, Rachel; Wanke, Kay L; Meissner, Helen I

2018-01-13

The purpose of this study is to describe the focus and comprehensiveness of domains measured in e-cigarette research. A portfolio analysis of National Institutes of Health grants focusing on e-cigarette research and funded between the fiscal years 2007 and 2015 was conducted. Grant proposals were retrieved using a government database and coded using the Host-Agent-Vector-Environment (HAVE) model as a framework to characterise the measures proposed. Eighty-one projects met the criteria for inclusion in the analysis. The primary HAVE focus most commonly found was Host (73%), followed by Agent (21%), Vector (6%) and Environment (0%). Intrapersonal measures and use trajectories were the most common measures in studies that include Host measures (n=59 and n=51, respectively). Product composition was the most common area of measurement in Agent studies (n=24), whereas Marketing (n=21) was the most common (n=21) area of Vector measurement. When Environment measures were examined as secondary measures in studies, they primarily focused on measuring Peer, Occupation and Social Networks (n=18). Although all studies mentioned research on e-cigarettes, most (n=52; 64%) did not specify the type of e-cigarette device or liquid solution under study. This analysis revealed a heavy focus on Host measures (73%) and a lack of focus on Environment measures. The predominant focus on Host measures may have the unintended effect of limiting the evidence base for tobacco control and regulatory science. Further, a lack of specificity about the e-cigarette product under study will make comparing results across studies and using the outcomes to inform tobacco policy difficult. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Implication of haematophagous arthropod salivary proteins in host-vector interactions.

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Fontaine, Albin; Diouf, Ibrahima; Bakkali, Nawal; Missé, Dorothée; Pagès, Frédéric; Fusai, Thierry; Rogier, Christophe; Almeras, Lionel

2011-09-28

The saliva of haematophagous arthropods contains an array of anti-haemostatic, anti-inflammatory and immunomodulatory molecules that contribute to the success of the blood meal. The saliva of haematophagous arthropods is also involved in the transmission and the establishment of pathogens in the host and in allergic responses. This survey provides a comprehensive overview of the pharmacological activity and immunogenic properties of the main salivary proteins characterised in various haematophagous arthropod species. The potential biological and epidemiological applications of these immunogenic salivary molecules will be discussed with an emphasis on their use as biomarkers of exposure to haematophagous arthropod bites or vaccine candidates that are liable to improve host protection against vector-borne diseases.

From Fossil Parasitoids to Vectors: Insects as Parasites and Hosts.

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Nagler, Christina; Haug, Joachim T

2015-01-01

Within Metazoa, it has been proposed that as many as two-thirds of all species are parasitic. This propensity towards parasitism is also reflected within insects, where several lineages independently evolved a parasitic lifestyle. Parasitic behaviour ranges from parasitic habits in the strict sense, but also includes parasitoid, phoretic or kleptoparasitic behaviour. Numerous insects are also the host for other parasitic insects or metazoans. Insects can also serve as vectors for numerous metazoan, protistan, bacterial and viral diseases. The fossil record can report this behaviour with direct (parasite associated with its host) or indirect evidence (insect with parasitic larva, isolated parasitic insect, pathological changes of host). The high abundance of parasitism in the fossil record of insects can reveal important aspects of parasitic lifestyles in various evolutionary lineages. For a comprehensive view on fossil parasitic insects, we discuss here different aspects, including phylogenetic systematics, functional morphology and a direct comparison of fossil and extant species. Copyright © 2015 Elsevier Ltd. All rights reserved.

A review of food-grade vectors in lactic acid bacteria: from the laboratory to their application.

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Landete, José Maria

2017-05-01

Lactic acid bacteria (LAB) have a long history of use in fermented foods and as probiotics. Genetic manipulation of these microorganisms has great potential for new applications in food safety, as well as in the development of improved food products and in health. While genetic engineering of LAB could have a major positive impact on the food and pharmaceutical industries, progress could be prevented by legal issues related to the controversy surrounding this technology. The safe use of genetically modified LAB requires the development of food-grade cloning systems containing only the DNA from homologous hosts or generally considered as safe organisms, and not dependent antibiotic markers. The rationale for the development of cloning vectors derived from cryptic LAB plasmids is the need for new genetic engineering tools, therefore a vision from cryptic plasmids to applications in food-grade vectors for LAB plasmids is shown in this review. Replicative and integrative vectors for the construction of food-grade vectors, and the relationship between resistance mechanism and expression systems, will be treated in depth in this paper. Finally, we will discuss the limited use of these vectors, and the problems arising from their use.

Infection history of the blood-meal host dictates pathogenic potential of the Lyme disease spirochete within the feeding tick vector.

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Bharti Bhatia

2018-04-01

Full Text Available Lyme disease in humans is caused by several genospecies of the Borrelia burgdorferi sensu lato (s.l. complex of spirochetal bacteria, including B. burgdorferi, B. afzelii and B. garinii. These bacteria exist in nature as obligate parasites in an enzootic cycle between small vertebrate hosts and Ixodid tick vectors, with humans representing incidental hosts. During the natural enzootic cycle, infected ticks in endemic areas feed not only upon naïve hosts, but also upon seropositive infected hosts. In the current study, we considered this environmental parameter and assessed the impact of the immune status of the blood-meal host on the phenotype of the Lyme disease spirochete within the tick vector. We found that blood from a seropositive host profoundly attenuates the infectivity (>104 fold of homologous spirochetes within the tick vector without killing them. This dramatic neutralization of vector-borne spirochetes was not observed, however, when ticks and blood-meal hosts carried heterologous B. burgdorferi s.l. strains, or when mice lacking humoral immunity replaced wild-type mice as blood-meal hosts in similar experiments. Mechanistically, serum-mediated neutralization does not block induction of host-adapted OspC+ spirochetes during tick feeding, nor require tick midgut components. Significantly, this study demonstrates that strain-specific antibodies elicited by B. burgdorferi s.l. infection neutralize homologous bacteria within feeding ticks, before the Lyme disease spirochetes enter a host. The blood meal ingested from an infected host thereby prevents super-infection by homologous spirochetes, while facilitating transmission of heterologous B. burgdorferi s.l. strains. This finding suggests that Lyme disease spirochete diversity is stably maintained within endemic populations in local geographic regions through frequency-dependent selection of rare alleles of dominant polymorphic surface antigens.

Elucidating transmission dynamics and host-parasite-vector relationships for rodent-borne Bartonella spp. in Madagascar

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Cara E. Brook

2017-09-01

Full Text Available Bartonella spp. are erythrocytic bacteria transmitted via arthropod vectors, which infect a broad range of vertebrate hosts, including humans. We investigated transmission dynamics and host-parasite-vector relationships for potentially zoonotic Bartonella spp. in invasive Rattus rattus hosts and associated arthropod ectoparasites in Madagascar. We identified five distinct species of Bartonella (B. elizabethae 1, B. elizabethae 2, B. phoceensis 1, B. rattimassiliensis 1, and B. tribocorum 1 infecting R. rattus rodents and their ectoparasites. We fit standard epidemiological models to species-specific age-prevalence data for the four Bartonella spp. with sufficient data, thus quantifying age-structured force of infection. Known zoonotic agents, B. elizabethae 1 and 2, were best described by models exhibiting high forces of infection in early age class individuals and allowing for recovery from infection, while B. phoceensis 1 and B. rattimassiliensis 1 were best fit by models of lifelong infection without recovery and substantially lower forces of infection. Nested sequences of B. elizabethae 1 and 2 were recovered from rodent hosts and their Synopsyllus fonquerniei and Xenopsylla cheopsis fleas, with a particularly high prevalence in the outdoor-dwelling, highland-endemic S. fonquerniei. These findings expand on force of infection analyses to elucidate the ecological niche of the zoonotic Bartonella elizabethae complex in Madagascar, hinting at a potential vector role for S. fonquerniei. Our analyses underscore the uniqueness of such ecologies for Bartonella species, which pose a variable range of potential zoonotic threats.

Understanding the Effects of Host Evolution and Skin Bacteria Composition on Disease Vector Choices

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2016-04-14

Distribution Unlimited UU UU UU UU 14-04-2016 1-Sep-2014 31-Dec-2015 Final Report: Understanding the effects of host evolution and skin bacteria ...S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 mosquito, skin, bacteria , primate REPORT...reviewed journals: Final Report: Understanding the effects of host evolution and skin bacteria composition on disease vector choices Report Title Here

Surveillance of potential hosts and vectors of scrub typhus in Taiwan.

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Kuo, Chi-Chien; Lee, Pei-Lung; Chen, Chun-Hsung; Wang, Hsi-Chieh

2015-12-01

Scrub typhus is a lethal infectious disease vectored by larval trombiculid mites (i.e. chiggers) infected with Orientia tsutsugamushi (OT) and recent decades have witnessed an emergence of scrub typhus in several countries. Identification of chigger species and their vertebrate hosts is fundamental for the assessment of human risks to scrub typhus under environmental changes, but intensive and extensive survey of chiggers and their hosts is still lacking in Taiwan. Chiggers were collected from shrews and rodents in nine counties of Taiwan and were assayed for OT infections with nested polymerase chain reaction (PCR). PCR products were further sequenced to reveal probable OT strains. Rodents were assessed for OT exposure by immunofluorescent antibody assay. Lastly, incidence rate of scrub typhus in each county was associated with loads and prevalence of chigger infestations, seropositivity rate in rodents, and OT positivity rate in chiggers. Rattus losea was the most abundant (48.7% of 1,285 individuals) and widespread (occurred in nine counties) small mammal species and hosted the majority of chiggers (76.4% of 128,520 chiggers). Leptotrombidium deliense was the most common (64.9% of all identified chiggers) and widespread (occurred in seven counties) chigger species but was replaced by Leptotrombidium pallidum or Leptotrombidium scutellare during the cold seasons in two counties (Matsu and Kinmen) where winter temperatures were lower than other study sites. Seropositivity rate for OT exposure in 876 assayed rodents was 43.0% and OT positivity rate in 347 pools of chiggers was 55.9%, with 15 OT strains identified in the 107 successfully sequenced samples. Incidence rate of scrub typhus was positively correlated with chigger loads, prevalence of chigger infestations, seropositivity rate but not OT positivity rate in chiggers. Our study reveals R. losea as the primary host for chiggers and there exists a geographical and seasonal variation in chigger species in

Yeast communities from host plants and associated Drosophila in southern arizona: new isolations and analysis of the relative importance of hosts and vectors on comunity composition.

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Ganter, Philip F; Starmer, William T; Lachance, Marc-Andre; Phaff, Herman J

1986-10-01

The yeast communities from slime fluxes of three deciduous trees (Prosopis juliflora, Populus fremontii and Quercus emoryi) and the necroses of two cacti (Opuntia phaeacantha and Carnegiea gigantea) were surveyed in the region of Tucson, Arizona. In addition, the yeasts carried by dipterans associated with the fluxes or necroses (Drosophila carbonaria, D. brooksae, D. nigrospiracula, D. mettleri, and Aulacigaster leucopeza) were sampled. The results indicate that each host sampled had a distinct community of yeasts associated with it. The dipterans, which can act as vectors of the yeasts, deposited yeasts from other sources in addition to those found on their associated hosts. It is argued that host plant physiology is relatively more important than the activity of the vector in determining yeast community composition. Furthermore, the average number of yeast species per flux or necrosis is not different from the average number of yeast species per fly. It is hypothesized that the vector may affect the number of species per individual flux or not, and that the number is lower than the rot or necrosis could potentially support.

Food-grade host/vector expression system for Lactobacillus casei based on complementation of plasmid-associated phospho-beta-galactosidase gene lacG.

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Takala, T M; Saris, P E J; Tynkkynen, S S H

2003-01-01

A new food-grade host/vector system for Lactobacillus casei based on lactose selection was constructed. The wild-type non-starter host Lb. casei strain E utilizes lactose via a plasmid-encoded phosphotransferase system. For food-grade cloning, a stable lactose-deficient mutant was constructed by deleting a 141-bp fragment from the phospho-beta-galactosidase gene lacG via gene replacement. The deletion resulted in an inactive phospho-beta-galactosidase enzyme with an internal in-frame deletion of 47 amino acids. A complementation plasmid was constructed containing a replicon from Lactococcus lactis, the lacG gene from Lb. casei, and the constitutive promoter of pepR for lacG expression from Lb. rhamnosus. The expression of the lacG gene from the resulting food-grade plasmid pLEB600 restored the ability of the lactose-negative mutant strain to grow on lactose to the wild-type level. The vector pLEB600 was used for expression of the proline iminopeptidase gene pepI from Lb. helveticus in Lb. casei. The results show that the food-grade expression system reported in this paper can be used for expression of foreign genes in Lb. casei.

Symbiotic zooxanthellae provide the host-coral Montipora digitata with polyunsaturated fatty acids.

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Papina, M; Meziane, T; van Woesik, R

2003-07-01

We compared the fatty acid composition of the host-coral Montipora digitata with the fatty acid composition in the coral's endosymbiotic dinoflagellates (zooxanthellae). Fatty acids as methyl esters were determined using gas chromatography (GC) and verified by GC-mass spectrometry. We found the main difference between the fatty acids in the host and their symbionts were that zooxanthellae supported higher proportions of polyunsaturated fatty acids. The presence of fatty acids specific to dinoflagellates (i.e. 18:4omega3, 22:5omega3 and 22:6omega3) in the host tissue suggests that zooxanthellae provide the coral host not only with saturated fatty acids, but also with diverse polyunsaturated fatty acids.

Reptiles as potential vectors and hosts of the amphibian pathogen Batrachochytrium dendrobatidis in Panama.

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Kilburn, Vanessa L; Ibáñez, Roberto; Green, David M

2011-12-06

Chytridiomycosis, the disease caused by Batrachochytrium dendrobatidis, is considered to be a disease exclusively of amphibians. However, B. dendrobatidis may also be capable of persisting in the environment, and non-amphibian vectors or hosts may contribute to disease transmission. Reptiles living in close proximity to amphibians and sharing similar ecological traits could serve as vectors or reservoir hosts for B. dendrobatidis, harbouring the organism on their skin without succumbing to disease. We surveyed for the presence of B. dendrobatidis DNA among 211 lizards and 8 snakes at 8 sites at varying elevations in Panama where the syntopic amphibians were at pre-epizootic, epizootic or post-epizootic stages of chytridiomycosis. Detection of B. dendrobatidis DNA was done using qPCR analysis. Evidence of the amphibian pathogen was present at varying intensities in 29 of 79 examined Anolis humilis lizards (32%) and 9 of 101 A. lionotus lizards (9%), and in one individual each of the snakes Pliocercus euryzonus, Imantodes cenchoa, and Nothopsis rugosus. In general, B. dendrobatidis DNA prevalence among reptiles was positively correlated with the infection prevalence among co-occurring anuran amphibians at any particular site (r = 0.88, p = 0.004). These reptiles, therefore, may likely be vectors or reservoir hosts for B. dendrobatidis and could serve as disease transmission agents. Although there is no evidence of B. dendrobatidis disease-induced declines in reptiles, cases of coincidence of reptile and amphibian declines suggest this potentiality. Our study is the first to provide evidence of non-amphibian carriers for B. dendrobatidis in a natural Neotropical environment.

A plant pathogenic bacterium exploits the tricarboxylic acid cycle metabolic pathway of its insect vector

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Nehela, Yasser; Hijaz, Faraj; Vincent, Christopher I.

2018-01-01

ABSTRACT Huanglongbing in citrus is caused by a phloem-limited, uncultivable, gram-negative α-proteobacterium, Candidatus Liberibacter asiaticus (CLas). CLas is transmitted by the phloem-sucking insect, Diaphorina citri (Hemiptera: Liviidae), in a persistent, circulative, and propagative manner. In this study, we investigated the metabolomic and respiration rates changes in D. citri upon infection with CLas using gas chromatography-mass spectrometry (GC-MS) and gas exchange analysis. The level of glycine, L-serine, L-threonine, and gamma-amino butyric acid were higher in CLas-infected D. citri, while L-proline, L-aspartic acid, and L-pyroglutamic acid were lower in CLas-infected D. citri compared with the control. Citric acid was increased in CLas-infected D. citri, whereas malic and succinic acids were reduced. Interestingly, most of the reduced metabolites such as malate, succinate, aspartate, and L-proline are required for the growth of CLas. The increase in citric acid, serine, and glycine indicated that CLas induced glycolysis and the tricarboxylic acid cycle (TCA) in its vector. In agreement with the GC-MS results, the gene expression results also indicated that glycolysis and TCA were induced in CLas-infected D. citri and this was accompanied with an increases in respiration rate. Phosphoric acid and most of the sugar alcohols were higher in CLas-infected D. citri, indicating a response to the biotic stress or cell damage. Only slight increases in the levels of few sugars were observed in CLas-infected D. citri, which indicated that sugars are tightly regulated by D. citri. Our results indicated that CLas induces nutrient and energetic stress in its host insect. This study may provide some insights into the mechanism of colonization of CLas in its vector. PMID:28594267

Fitness Cost of Litomosoides sigmodontis Filarial Infection in Mite Vectors; Implications of Infected Haematophagous Arthropod Excretory Products in Host-Vector Interactions

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Adélaïde Nieguitsila

2013-01-01

Full Text Available Filariae are a leading cause of infections which are responsible for serious dermatological, ocular, and vascular lesions. Infective third stage larvae (L3 are transmitted through the bite of a haematophagous vector. Litomosoides sigmodontis is a well-established model of filariasis in the mouse, with the vector being the mite Ornithonyssus bacoti. The aim of the study was to analyse the filarial infection in mites to determine the consequences of filarial infection in the blood-feeding and the reproduction of mites as well as in the regulation of vector-induced inflammation in the mouse skin. Firstly, L3 are unevenly distributed throughout the host population and the majority of the population harbours a moderate infection (1 to 6 L3. Filarial infection does not significantly affect the probing delay for blood feeding. The number of released protonymphs is lower in infected mites but is not correlated with the L3 burden. Finally, induced excreted proteins from infected mites but not from uninfected mites stimulate TNF-α and the neutrophil-chemoattractant KC production by antigen-presenting cells (APCs. Altogether, these results describe the modification of the mite behavior under filarial infection and suggest that the immunomodulatory capacity of the mite may be modified by the presence of the parasite, hindering its defensive ability towards the vertebrate host.

Synchrony of sylvatic dengue isolations: a multi-host, multi-vector SIR model of dengue virus transmission in Senegal.

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Benjamin M Althouse

Full Text Available Isolations of sylvatic dengue-2 virus from mosquitoes, humans and non-human primates in Senegal show synchronized multi-annual dynamics over the past 50 years. Host demography has been shown to directly affect the period between epidemics in other pathogen systems, therefore, one might expect unsynchronized multi-annual cycles occurring in hosts with dramatically different birth rates and life spans. However, in Senegal, we observe a single synchronized eight-year cycle across all vector species, suggesting synchronized dynamics in all vertebrate hosts. In the current study, we aim to explore two specific hypotheses: 1 primates with different demographics will experience outbreaks of dengue at different periodicities when observed as isolated systems, and that coupling of these subsystems through mosquito biting will act to synchronize incidence; and 2 the eight-year periodicity of isolations observed across multiple primate species is the result of long-term cycling in population immunity in the host populations. To test these hypotheses, we develop a multi-host, multi-vector Susceptible, Infected, Removed (SIR model to explore the effects of coupling multiple host-vector systems of dengue virus transmission through cross-species biting rates. We find that under small amounts of coupling, incidence in the host species synchronize. Long-period multi-annual dynamics are observed only when prevalence in troughs reaches vanishingly small levels (< 10(-10, suggesting that these dynamics are inconsistent with sustained transmission in this setting, but are consistent with local dengue virus extinctions followed by reintroductions. Inclusion of a constant introduction of infectious individuals into the system causes the multi-annual periods to shrink, while the effects of coupling remain the same. Inclusion of a stochastic rate of introduction allows for multi-annual periods at a cost of reduced synchrony. Thus, we conclude that the eight-year period

Recurrent evolution of host and vector association in bacteria of the Borrelia burgdorferi sensu lato species complex.

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Becker, Noémie S; Margos, Gabriele; Blum, Helmut; Krebs, Stefan; Graf, Alexander; Lane, Robert S; Castillo-Ramírez, Santiago; Sing, Andreas; Fingerle, Volker

2016-09-15

The Borrelia burgdorferi sensu lato (s.l.) species complex consists of tick-transmitted bacteria and currently comprises approximately 20 named and proposed genospecies some of which are known to cause Lyme Borreliosis. Species have been defined via genetic distances and ecological niches they occupy. Understanding the evolutionary relationship of species of the complex is fundamental to explaining patterns of speciation. This in turn forms a crucial basis to frame testable hypotheses concerning the underlying processes including host and vector adaptations. Illumina Technology was used to obtain genome-wide sequence data for 93 strains of 14 named genospecies of the B. burgdorferi species complex and genomic data already published for 18 additional strain (including one new species) was added. Phylogenetic reconstruction based on 114 orthologous single copy genes shows that the genospecies represent clearly distinguishable taxa with recent and still ongoing speciation events apparent in Europe and Asia. The position of Borrelia species in the phylogeny is consistent with host associations constituting a major driver for speciation. Interestingly, the data also demonstrate that vector associations are an additional driver for diversification in this tick-borne species complex. This is particularly obvious in B. bavariensis, a rodent adapted species that has diverged from the bird-associated B. garinii most likely in Asia. It now consists of two populations one of which most probably invaded Europe following adaptation to a new vector (Ixodes ricinus) and currently expands its distribution range. The results imply that genotypes/species with novel properties regarding host or vector associations have evolved recurrently during the history of the species complex and may emerge at any time. We suggest that the finding of vector associations as a driver for diversification may be a general pattern for tick-borne pathogens. The core genome analysis presented here

A Bacterial Parasite Effector Mediates Insect Vector Attraction in Host Plants Independently of Developmental Changes

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Orlovskis, Zigmunds; Hogenhout, Saskia A.

2016-01-01

Parasites can take over their hosts and trigger dramatic changes in host appearance and behavior that are typically interpreted as extended phenotypes that promote parasite survival and fitness. For example, Toxoplasma gondii is thought to manipulate the behaviors of infected rodents to aid transmission to cats and parasitic trematodes of the genus Ribeiroia alter limb development in their amphibian hosts to facilitate predation of the latter by birds. Plant parasites and pathogens also reprogram host development and morphology. However, whereas some parasite-induced morphological alterations may have a direct benefit to the fitness of the parasite and may therefore be adaptive, other host alterations may be side effects of parasite infections having no adaptive effects on parasite fitness. Phytoplasma parasites of plants often induce the development of leaf-like flowers (phyllody) in their host plants, and we previously found that the phytoplasma effector SAP54 generates these leaf-like flowers via the degradation of plant MADS-box transcription factors (MTFs), which regulate all major aspects of development in plants. Leafhoppers prefer to reproduce on phytoplasma-infected and SAP54-trangenic plants leading to the hypothesis that leafhopper vectors are attracted to plants with leaf-like flowers. Surprisingly, here we show that leafhopper attraction occurs independently of the presence of leaf-like flowers. First, the leafhoppers were also attracted to SAP54 transgenic plants without leaf-like flowers and to single leaves of these plants. Moreover, leafhoppers were not attracted to leaf-like flowers of MTF-mutant plants without the presence of SAP54. Thus, the primary role of SAP54 is to attract leafhopper vectors, which spread the phytoplasmas, and the generation of leaf-like flowers may be secondary or a side effect of the SAP54-mediated degradation of MTFs. PMID:27446117

Heterogeneous Feeding Patterns of the Dengue Vector, Aedes aegypti, on Individual Human Hosts in Rural Thailand

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Harrington, Laura C.; Fleisher, Andrew; Ruiz-Moreno, Diego; Vermeylen, Francoise; Wa, Chrystal V.; Poulson, Rebecca L.; Edman, John D.; Clark, John M.; Jones, James W.; Kitthawee, Sangvorn; Scott, Thomas W.

2014-01-01

Background Mosquito biting frequency and how bites are distributed among different people can have significant epidemiologic effects. An improved understanding of mosquito vector-human interactions would refine knowledge of the entomological processes supporting pathogen transmission and could reveal targets for minimizing risk and breaking pathogen transmission cycles. Methodology and principal findings We used human DNA blood meal profiling of the dengue virus (DENV) vector, Aedes aegypti, to quantify its contact with human hosts and to infer epidemiologic implications of its blood feeding behavior. We determined the number of different people bitten, biting frequency by host age, size, mosquito age, and the number of times each person was bitten. Of 3,677 engorged mosquitoes collected and 1,186 complete DNA profiles, only 420 meals matched people from the study area, indicating that Ae. aegypti feed on people moving transiently through communities to conduct daily business. 10–13% of engorged mosquitoes fed on more than one person. No biting rate differences were detected between high- and low-dengue transmission seasons. We estimate that 43–46% of engorged mosquitoes bit more than one person within each gonotrophic cycle. Most multiple meals were from residents of the mosquito collection house or neighbors. People ≤25 years old were bitten less often than older people. Some hosts were fed on frequently, with three hosts bitten nine times. Interaction networks for mosquitoes and humans revealed biologically significant blood feeding hotspots, including community marketplaces. Conclusion and significance High multiple-feeding rates and feeding on community visitors are likely important features in the efficient transmission and rapid spread of DENV. These results help explain why reducing vector populations alone is difficult for dengue prevention and support the argument for additional studies of mosquito feeding behavior, which when integrated with a

Heterogeneous feeding patterns of the dengue vector, Aedes aegypti, on individual human hosts in rural Thailand.

Directory of Open Access Journals (Sweden)

Laura C Harrington

2014-08-01

Full Text Available Mosquito biting frequency and how bites are distributed among different people can have significant epidemiologic effects. An improved understanding of mosquito vector-human interactions would refine knowledge of the entomological processes supporting pathogen transmission and could reveal targets for minimizing risk and breaking pathogen transmission cycles.We used human DNA blood meal profiling of the dengue virus (DENV vector, Aedes aegypti, to quantify its contact with human hosts and to infer epidemiologic implications of its blood feeding behavior. We determined the number of different people bitten, biting frequency by host age, size, mosquito age, and the number of times each person was bitten. Of 3,677 engorged mosquitoes collected and 1,186 complete DNA profiles, only 420 meals matched people from the study area, indicating that Ae. aegypti feed on people moving transiently through communities to conduct daily business. 10-13% of engorged mosquitoes fed on more than one person. No biting rate differences were detected between high- and low-dengue transmission seasons. We estimate that 43-46% of engorged mosquitoes bit more than one person within each gonotrophic cycle. Most multiple meals were from residents of the mosquito collection house or neighbors. People ≤ 25 years old were bitten less often than older people. Some hosts were fed on frequently, with three hosts bitten nine times. Interaction networks for mosquitoes and humans revealed biologically significant blood feeding hotspots, including community marketplaces.High multiple-feeding rates and feeding on community visitors are likely important features in the efficient transmission and rapid spread of DENV. These results help explain why reducing vector populations alone is difficult for dengue prevention and support the argument for additional studies of mosquito feeding behavior, which when integrated with a greater understanding of human behavior will refine estimates of

Diversity and spation distribution of vectors and hosts of T. brucei gambiense in forest zones of Southern Cameroon: Epidemiological implications

NARCIS (Netherlands)

Massussi, J.A.; Mbida Mbida, J.A.; Djieto-Lordon, C.; Njiokou, F.; Laveissière, C.; Ploeg, van der J.D.

2010-01-01

Host and vector distribution of Trypanosoma brucei gambiense was studied in relation to habitat types and seasons. Six (19.35%) of the 31 mammal species recorded in Bipindi were reservoir hosts. Cercopithecus nictitans was confined to the undisturbed forest and the low intensive shifting cultivation

Quantification of vector and host competence for Japanese encephalitis virus: a systematic review of the literature

Science.gov (United States)

Japanese encephalitis virus (JEV) is a virus of the Flavivirus genus that may result in encephalitis in human hosts. This vector-borne zoonosis occurs in Eastern and Southeastern Asia and an intentional or inadvertent introduction into the United States (US) will have major public health and economi...

Meta-analysis of the effects of insect vector saliva on host immune responses and infection of vector-transmitted pathogens: a focus on leishmaniasis.

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Brittany Ockenfels

2014-10-01

Full Text Available A meta-analysis of the effects of vector saliva on the immune response and progression of vector-transmitted disease, specifically with regard to pathology, infection level, and host cytokine levels was conducted. Infection in the absence or presence of saliva in naïve mice was compared. In addition, infection in mice pre-exposed to uninfected vector saliva was compared to infection in unexposed mice. To control for differences in vector and pathogen species, mouse strain, and experimental design, a random effects model was used to compare the ratio of the natural log of the experimental to the control means of the studies. Saliva was demonstrated to enhance pathology, infection level, and the production of Th2 cytokines (IL-4 and IL-10 in naïve mice. This effect was observed across vector/pathogen pairings, whether natural or unnatural, and with single salivary proteins used as a proxy for whole saliva. Saliva pre-exposure was determined to result in less severe leishmaniasis pathology when compared with unexposed mice infected either in the presence or absence of sand fly saliva. The results of further analyses were not significant, but demonstrated trends toward protection and IFN-γ elevation for pre-exposed mice.

Meta-analysis of the effects of insect vector saliva on host immune responses and infection of vector-transmitted pathogens: a focus on leishmaniasis.

Science.gov (United States)

Ockenfels, Brittany; Michael, Edwin; McDowell, Mary Ann

2014-10-01

A meta-analysis of the effects of vector saliva on the immune response and progression of vector-transmitted disease, specifically with regard to pathology, infection level, and host cytokine levels was conducted. Infection in the absence or presence of saliva in naïve mice was compared. In addition, infection in mice pre-exposed to uninfected vector saliva was compared to infection in unexposed mice. To control for differences in vector and pathogen species, mouse strain, and experimental design, a random effects model was used to compare the ratio of the natural log of the experimental to the control means of the studies. Saliva was demonstrated to enhance pathology, infection level, and the production of Th2 cytokines (IL-4 and IL-10) in naïve mice. This effect was observed across vector/pathogen pairings, whether natural or unnatural, and with single salivary proteins used as a proxy for whole saliva. Saliva pre-exposure was determined to result in less severe leishmaniasis pathology when compared with unexposed mice infected either in the presence or absence of sand fly saliva. The results of further analyses were not significant, but demonstrated trends toward protection and IFN-γ elevation for pre-exposed mice.

Fatty Acid Composition of Novel Host Jack Pine Do Not Prevent Host Acceptance and Colonization by the Invasive Mountain Pine Beetle and Its Symbiotic Fungus

Science.gov (United States)

Ishangulyyeva, Guncha; Najar, Ahmed; Curtis, Jonathan M.

2016-01-01

Fatty acids are major components of plant lipids and can affect growth and development of insect herbivores. Despite a large literature examining the roles of fatty acids in conifers, relatively few studies have tested the effects of fatty acids on insect herbivores and their microbial symbionts. Particularly, whether fatty acids can affect the suitability of conifers for insect herbivores has never been studied before. Thus, we evaluated if composition of fatty acids impede or facilitate colonization of jack pine (Pinus banksiana) by the invasive mountain pine beetle (Dendroctonus ponderosae) and its symbiotic fungus (Grosmannia clavigera). This is the first study to examine the effects of tree fatty acids on any bark beetle species and its symbiotic fungus. In a novel bioassay, we found that plant tissues (hosts and non-host) amended with synthetic fatty acids at concentrations representative of jack pine were compatible with beetle larvae. Likewise, G. clavigera grew in media amended with lipid fractions or synthetic fatty acids at concentrations present in jack pine. In contrast, fatty acids and lipid composition of a non-host were not suitable for the beetle larvae or the fungus. Apparently, concentrations of individual, rather than total, fatty acids determined the suitability of jack pine. Furthermore, sampling of host and non-host tree species across Canada demonstrated that the composition of jack pine fatty acids was similar to the different populations of beetle’s historical hosts. These results demonstrate that fatty acids composition compatible with insect herbivores and their microbial symbionts can be important factor defining host suitability to invasive insects. PMID:27583820

Synergism between ammonia, lactic acid and carboxylic acids as kairomones in the host-seeking behaviour of the malaria mosquito Anopheles gambiae sensu stricto (Diptera: Culicidae)

NARCIS (Netherlands)

Smallegange, R.C.; Qiu, Y.T.; Loon, van J.J.A.; Takken, W.

2005-01-01

Host odours play a major role in the orientation and host location of blood-feeding mosquitoes. Anopheles gambiae Giles sensu stricto, which is the most important malaria vector in Africa, is a highly anthropophilic mosquito species, and the host-seeking behaviour of the females of this mosquito is

EGVII endoglucanase and nucleic acids encoding the same

Science.gov (United States)

Dunn-Coleman, Nigel [Los Gatos, CA; Goedegebuur, Frits [Vlaardingen, NL; Ward, Michael [San Francisco, CA; Yao, Jian [Sunnyvale, CA

2009-05-05

The present invention provides an endoglucanase nucleic acid sequence, designated egl7, and the corresponding EGVII amino acid sequence. The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding EGVII, recombinant EGVII proteins and methods for producing the same.

Hosts and vectors of Trypanosoma cruzi discrete typing units in the Chagas disease endemic region of the Paraguayan Chaco

OpenAIRE

ACOSTA, NIDIA; L?PEZ, ELSA; LEWIS, MICHAEL D.; LLEWELLYN, MARTIN S.; G?MEZ, ANA; ROM?N, FABIOLA; MILES, MICHAEL A.; YEO, MATTHEW

2017-01-01

SUMMARY Active Trypanosoma cruzi transmission persists in the Gran Chaco region, which is considered hyperendemic for Chagas disease. Understanding domestic and sylvatic transmission cycles and therefore the relationship between vectors and mammalian hosts is crucial to designing and implementing improved effective control strategies. Here we describe the species of triatomine vectors and the sylvatic mammal reservoirs of T. cruzi, in different localities of the Paraguayan and Bolivian Chaco....

Fatty acid composition of symbiotic zooxanthellae in relation to their hosts.

Science.gov (United States)

Bishop, D G; Kenrick, J R

1980-10-01

Gymnodinoid dinoflagellate symbionts, commonly referred to as zooxanthellae, are widely distributed among marine invertebrates. It has been assumed that they represent only one species,Gymnodinium microadriaticum. The fatty acid composition of total lipids and galactolipids of zooxanthellae isolated from 8 species of corals, 3 species of clams and a foraminiferan have been analyzed and found to vary according to the host. For example, the content of eicosapentaenoic acid in clam zooxanthellae monogalactosyldiacylglycerol was less than 2%, whereas in the same lipid from coral zooxanthellae, the content ranged from 9 to 22%. Corresponding values for the acid in digalactosyl-diacylglycerol were 1-8% from clam zooxanthellae and 23-40% from coral zooxanthellae. Coral zooxanthellae monogalactosyldiacylglycerol contain higher levels of octadecatetraenoic acid than are found in digalactosyldiacylglycerol, whereas the reverse is true in clam zooxanthellae. The fatty acid composition of the lipids of an axenic culture of zooxanthellae isolated from the clamTridacna maxima are similar to those of cells freshly isolated from the host. The results suggest either that the host is capable of affecting the fatty acid metabolism of the symbiont or that different strains of zooxanthellae occur in corals and clams.

The Role of Microbial Amino Acid Metabolism in Host Metabolism

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Evelien P. J. G. Neis

2015-04-01

Full Text Available Disruptions in gut microbiota composition and function are increasingly implicated in the pathogenesis of obesity, insulin resistance, and type 2 diabetes mellitus. The functional output of the gut microbiota, including short-chain fatty acids and amino acids, are thought to be important modulators underlying the development of these disorders. Gut bacteria can alter the bioavailability of amino acids by utilization of several amino acids originating from both alimentary and endogenous proteins. In turn, gut bacteria also provide amino acids to the host. This could have significant implications in the context of insulin resistance and type 2 diabetes mellitus, conditions associated with elevated systemic concentrations of certain amino acids, in particular the aromatic and branched-chain amino acids. Moreover, several amino acids released by gut bacteria can serve as precursors for the synthesis of short-chain fatty acids, which also play a role in the development of obesity. In this review, we aim to compile the available evidence on the contribution of microbial amino acids to host amino acid homeostasis, and to assess the role of the gut microbiota as a determinant of amino acid and short-chain fatty acid perturbations in human obesity and type 2 diabetes mellitus.

Culicoides (Diptera: Ceratopogonidae) midges, the vectors of African horse sickness virus--a host/vector contact study in the Niayes area of Senegal.

Science.gov (United States)

Fall, Moussa; Diarra, Maryam; Fall, Assane G; Balenghien, Thomas; Seck, Momar T; Bouyer, Jérémy; Garros, Claire; Gimonneau, Geoffrey; Allène, Xavier; Mall, Iba; Delécolle, Jean-Claude; Rakotoarivony, Ignace; Bakhoum, Mame T; Dusom, Ange M; Ndao, Massouka; Konaté, Lassana; Faye, Ousmane; Baldet, Thierry

2015-01-21

African horse sickness (AHS) is an equine disease endemic to Senegal. The African horse sickness virus (AHSV) is transmitted to the mammalian hosts by midges of the Culicoides Latreille genus. During the last epizootic outbreak of AHS in Senegal in 2007, 1,169 horses died from this disease entailing an estimated cost of 1.4 million euros. In spite of the serious animal health and economic implications of AHS, very little is known about determinants involved in transmission such as contact between horses and the Culicoides species suspected of being its vectors. The monthly variation in host/vector contact was determined in the Niayes area, Senegal, an area which was severely affected by the 2007 outbreak of AHS. A horse-baited trap and two suction light traps (OVI type) were set up at each of five sites for three consecutive nights every month for one year. Of 254,338 Culicoides midges collected 209,543 (82.4%) were female and 44,795 (17.6%) male. Nineteen of the 41 species collected were new distribution records for Senegal. This increased the number of described Culicoides species found in Senegal to 53. Only 19 species, of the 41 species found in light trap, were collected in the horse-baited trap (23,669 specimens) largely dominated by Culicoides oxystoma (22,300 specimens, i.e. 94.2%) followed by Culicoides imicola (482 specimens, i.e. 2.0%) and Culicoides kingi (446 specimens, i.e. 1.9%). Culicoides oxystoma should be considered as a potential vector of AHSV in the Niayes area of Senegal due to its abundance on horses and its role in the transmission of other Culicoides-borne viruses.

Vector-Host Interactions of Culiseta melanura in a Focus of Eastern Equine Encephalitis Virus Activity in Southeastern Virginia.

Science.gov (United States)

Molaei, Goudarz; Armstrong, Philip M; Abadam, Charles F; Akaratovic, Karen I; Kiser, Jay P; Andreadis, Theodore G

2015-01-01

Eastern equine encephalitis virus (EEEV) causes a highly pathogenic mosquito-borne zoonosis that is responsible for sporadic outbreaks of severe illness in humans and equines in the eastern USA. Culiseta (Cs.) melanura is the primary vector of EEEV in most geographic regions but its feeding patterns on specific avian and mammalian hosts are largely unknown in the mid-Atlantic region. The objectives of our study were to: 1) identify avian hosts of Cs. melanura and evaluate their potential role in enzootic amplification of EEEV, 2) assess spatial and temporal patterns of virus activity during a season of intense virus transmission, and 3) investigate the potential role of Cs. melanura in epidemic/epizootic transmission of EEEV to humans and equines. Accordingly, we collected mosquitoes at 55 sites in Suffolk, Virginia in 2013, and identified the source of blood meals in engorged mosquitoes by nucleotide sequencing PCR products of the mitochondrial cytochrome b gene. We also examined field-collected mosquitoes for evidence of infection with EEEV using Vector Test, cell culture, and PCR. Analysis of 188 engorged Cs. melanura sampled from April through October 2013 indicated that 95.2%, 4.3%, and 0.5% obtained blood meals from avian, mammalian, and reptilian hosts, respectively. American Robin was the most frequently identified host for Cs. melanura (42.6% of blood meals) followed by Northern Cardinal (16.0%), European Starling (11.2%), Carolina Wren (4.3%), and Common Grackle (4.3%). EEEV was detected in 106 mosquito pools of Cs. melanura, and the number of virus positive pools peaked in late July with 22 positive pools and a Maximum Likelihood Estimation (MLE) infection rate of 4.46 per 1,000 mosquitoes. Our findings highlight the importance of Cs. melanura as a regional EEEV vector based on frequent feeding on virus-competent bird species. A small proportion of blood meals acquired from mammalian hosts suggests the possibility that this species may occasionally

Feast or famine: the host-pathogen battle over amino acids.

Science.gov (United States)

Zhang, Yanjia J; Rubin, Eric J

2013-07-01

Intracellular bacterial pathogens often rely on their hosts for essential nutrients. Host cells, in turn, attempt to limit nutrient availability, using starvation as a mechanism of innate immunity. Here we discuss both host mechanisms of amino acid starvation and the diverse adaptations of pathogens to their nutrient-deprived environments. These processes provide both key insights into immune subversion and new targets for drug development. © 2013 John Wiley & Sons Ltd.

A multi-layered mechanistic modelling approach to understand how effector genes extend beyond phytoplasma to modulate plant hosts, insect vectors and the environment.

Science.gov (United States)

Tomkins, Melissa; Kliot, Adi; Marée, Athanasius Fm; Hogenhout, Saskia A

2018-03-13

Members of the Candidatus genus Phytoplasma are small bacterial pathogens that hijack their plant hosts via the secretion of virulence proteins (effectors) leading to a fascinating array of plant phenotypes, such as witch's brooms (stem proliferations) and phyllody (retrograde development of flowers into vegetative tissues). Phytoplasma depend on insect vectors for transmission, and interestingly, these insect vectors were found to be (in)directly attracted to plants with these phenotypes. Therefore, phytoplasma effectors appear to reprogram plant development and defence to lure insect vectors, similarly to social engineering malware, which employs tricks to lure people to infected computers and webpages. A multi-layered mechanistic modelling approach will enable a better understanding of how phytoplasma effector-mediated modulations of plant host development and insect vector behaviour contribute to phytoplasma spread, and ultimately to predict the long reach of phytoplasma effector genes. Copyright © 2018. Published by Elsevier Ltd.

Intestinal Crosstalk between Bile Acids and Microbiota and Its Impact on Host Metabolism

DEFF Research Database (Denmark)

Wahlström, Annika; Sayin, Sama I; Marschall, Hanns-Ulrich

2016-01-01

The gut microbiota is considered a metabolic "organ" that not only facilitates harvesting of nutrients and energy from the ingested food but also produces numerous metabolites that signal through their cognate receptors to regulate host metabolism. One such class of metabolites, bile acids......, is produced in the liver from cholesterol and metabolized in the intestine by the gut microbiota. These bioconversions modulate the signaling properties of bile acids via the nuclear farnesoid X receptor and the G protein-coupled membrane receptor 5, which regulate numerous metabolic pathways in the host....... Conversely, bile acids can modulate gut microbial composition both directly and indirectly through activation of innate immune genes in the small intestine. Thus, host metabolism can be affected through microbial modifications of bile acids, which lead to altered signaling via bile acid receptors, but also...

The Bacteriome of Bat Flies (Nycteribiidae) from the Malagasy Region: a Community Shaped by Host Ecology, Bacterial Transmission Mode, and Host-Vector Specificity.

Science.gov (United States)

Wilkinson, David A; Duron, Olivier; Cordonin, Colette; Gomard, Yann; Ramasindrazana, Beza; Mavingui, Patrick; Goodman, Steven M; Tortosa, Pablo

2016-01-08

The Nycteribiidae are obligate blood-sucking Diptera (Hippoboscoidea) flies that parasitize bats. Depending on species, these wingless flies exhibit either high specialism or generalism toward their hosts, which may in turn have important consequences in terms of their associated microbial community structure. Bats have been hypothesized to be reservoirs of numerous infectious agents, some of which have recently emerged in human populations. Thus, bat flies may be important in the epidemiology and transmission of some of these bat-borne infectious diseases, acting either directly as arthropod vectors or indirectly by shaping pathogen communities among bat populations. In addition, bat flies commonly have associations with heritable bacterial endosymbionts that inhabit insect cells and depend on maternal transmission through egg cytoplasm to ensure their transmission. Some of these heritable bacteria are likely obligate mutualists required to support bat fly development, but others are facultative symbionts with unknown effects. Here, we present bacterial community profiles that were obtained from seven bat fly species, representing five genera, parasitizing bats from the Malagasy region. The observed bacterial diversity includes Rickettsia, Wolbachia, and several Arsenophonus-like organisms, as well as other members of the Enterobacteriales and a widespread association of Bartonella bacteria from bat flies of all five genera. Using the well-described host specificity of these flies and data on community structure from selected bacterial taxa with either vertical or horizontal transmission, we show that host/vector specificity and transmission mode are important drivers of bacterial community structure. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri.

Directory of Open Access Journals (Sweden)

Dara G Stockton

Full Text Available Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a whether development on specific host plant species influenced host plant preference in mature D. citri; and b the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24-48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate

The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri.

Science.gov (United States)

Stockton, Dara G; Martini, Xavier; Patt, Joseph M; Stelinski, Lukasz L

2016-01-01

Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a) whether development on specific host plant species influenced host plant preference in mature D. citri; and b) the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24-48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate Rutaceae in the area

Zika virus, vectors, reservoirs, amplifying hosts, and their potential to spread worldwide: what we know and what we should investigate urgently.

Science.gov (United States)

Vorou, Rengina

2016-07-01

The widespread epidemic of Zika virus infection in South and Central America and the Caribbean in 2015, along with the increased incidence of microcephaly in fetuses born to mothers infected with Zika virus and the potential for worldwide spread, indicate the need to review the current literature regarding vectors, reservoirs, and amplification hosts. The virus has been isolated in Africa in mosquitoes of the genera Aedes, Anopheles, and Mansonia, and in Southeast Asia and the Pacific area in mosquitoes of the genus Aedes. Aedes albopictus has invaded several countries in Central Africa and all Mediterranean countries, and continues to spread throughout Central and Northern Europe. The wide distribution of the virus in animal hosts and vectors favors the emergence of recombinants. The virus has been isolated in monkeys, and antibodies have been detected in domestic sheep, goats, horses, cows, ducks, rodents, bats, orangutans, and carabaos. It is a public health imperative to define the domestic and wild animal reservoirs, amplification hosts, and vector capacity of the genera Aedes, Anopheles, and Mansonia. These variables will define the geographic distribution of Zika virus along with the indicated timing and scale of the environmental public health interventions worldwide. Copyright © 2016 The Author. Published by Elsevier Ltd.. All rights reserved.

Molecular detection of Leishmania infection due to Leishmania major and Leishmania turanica in the vectors and reservoir host in Iran.

Science.gov (United States)

Rassi, Yavar; Oshaghi, Mohammad Ali; Azani, Sadegh Mohammadi; Abaie, Mohammad Reza; Rafizadeh, Sina; Mohebai, Mehdi; Mohtarami, Fatemeh; Zeinali, Mohammad kazem

2011-02-01

An epidemiological study was carried out on the vectors and reservoirs of cutaneous leishmaniasis in rural areas of Damghan district, Semnan province, central Iran, during 2008-2009. Totally, 6110 sand flies were collected using sticky papers and were subjected to molecular methods for detection of Leishmania parasite. Phlebotomus papatasi Scopoli was the common species in outdoor and indoor resting places. Polymerase chain reaction technique showed that 24 out of 218 P. papatasi (11%) and 4 out of 62 Phlebotomus caucasicus Marzinovskyi (6.5%) were positive for parasites Leishmania major Yakimoff and Schokhor. Twenty-one rodent reservoir hosts captured using Sherman traps were identified as Rhombomys opimus Lichtenstein (95%) and Meriones libycus Lichtenstein (5%). Microscopic investigation on blood smear of the animals for amastigote parasites revealed 8 (40%) rodents infected with R. opimus. L. major infection in these animals was then confirmed by polymerase chain reaction against internal transcribed spacer ribosomal DNA (rDNA) loci of the parasite followed by restriction fragment length polymorphism. Further, sequence analysis of 297 bp of ITS1-rDNA loci revealed the presence of L. major and Leishmania turanica in P. papatasi, and L. major in R. opimus. This is the first molecular report of L. major infection in both vectors (P. papatasi and P. caucasicus) and reservoir host (R. opimus) in this region. The results indicated that P. papatas was the primary vector of the disease and circulating the parasite between human and reservoirs, and P. caucasicus could be considered as a secondary vector. Further, our study showed that R. opimus is the most important host reservoir for maintenance of the parasite source in the area.

Composition of fatty acids in the Varroa destructor mites and their hosts, Apis mellifera drone-prepupae.

Science.gov (United States)

Dmitryjuk, Małgorzata; Zalewski, Kazimierz; Raczkowski, Marek; Żółtowska, Krystyna

2015-01-01

The fatty acid (FA) profile of lipids extracted from the Varroa destructor parasitic mite and its host, drone-prepupae of Apis mellifera, was determined by gas chromatography (GC). The percentages of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) were generally similar in parasites and their hosts. Fatty acids were arranged in the following descending order based on their content: MUFAs (ca. 52-55%), SFAs (ca. 41%) and PUFAs (ca. 3%). The predominant fatty acids were oleic acid (46% in mites, 44% in prepupae) and palmitic acid (23% and 30%, respectively). Varroa parasites differed from their hosts in the quantity of individual FAs and in their FA profiles. Three PUFAs noted in the host were not observed in parasitic mites, whereas the presence of C21:0, C24:0 and C22:1 FAs was reported in mites, but not in drones.

Venezuelan equine encephalitis emergence: Enhanced vector infection from a single amino acid substitution in the envelope glycoprotein

Science.gov (United States)

Brault, Aaron C.; Powers, Ann M.; Ortiz, Diana; Estrada-Franco, Jose G.; Navarro-Lopez, Roberto; Weaver, Scott C.

2004-01-01

In 1993 and 1996, subtype IE Venezuelan equine encephalitis (VEE) virus caused epizootics in the Mexican states of Chiapas and Oaxaca. Previously, only subtype IAB and IC VEE virus strains had been associated with major outbreaks of equine and human disease. The IAB and IC epizootics are believed to emerge via adaptation of enzootic (sylvatic, equine-avirulent) strains for high titer equine viremia that results in efficient infection of mosquito vectors. However, experimental equine infections with subtype IE equine isolates from the Mexican outbreaks demonstrated neuro-virulence but little viremia, inconsistent with typical VEE emergence mechanisms. Therefore, we hypothesized that changes in the mosquito vector host range might have contributed to the Mexican emergence. To test this hypothesis, we evaluated the susceptibility of the most abundant mosquito in the deforested Pacific coastal locations of the VEE outbreaks and a proven epizootic vector, Ochlerotatus taeniorhynchus. The Mexican epizootic equine isolates exhibited significantly greater infectivity compared with closely related enzootic strains, supporting the hypothesis that adaptation to an efficient epizootic vector contributed to disease emergence. Reverse genetic studies implicated a Ser → Asn substitution in the E2 envelope glycoprotein as the major determinant of the increased vector infectivity phenotype. Our findings underscore the capacity of RNA viruses to alter their vector host range through minor genetic changes, resulting in the potential for disease emergence. PMID:15277679

BGL6 beta-glucosidase and nucleic acids encoding the same

Science.gov (United States)

Dunn-Coleman, Nigel [Los Gatos, CA; Ward, Michael [San Francisco, CA

2009-09-01

The present invention provides a novel .beta.-glucosidase nucleic acid sequence, designated bgl6, and the corresponding BGL6 amino acid sequence. The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding BGL6, recombinant BGL6 proteins and methods for producing the same.

Emerging Vector-Borne Diseases - Incidence through Vectors.

Science.gov (United States)

Savić, Sara; Vidić, Branka; Grgić, Zivoslav; Potkonjak, Aleksandar; Spasojevic, Ljubica

2014-01-01

Vector-borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowadays, in intercontinental countries, there is a struggle with emerging diseases, which have found their way to appear through vectors. Vector-borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens, and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector-borne infectious diseases and disease outbreaks. It could affect the range and population of pathogens, host and vectors, transmission season, etc. Reliable surveillance for diseases that are most likely to emerge is required. Canine vector-borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, ehrlichiosis, and leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fundamental role at primarily prevention and then treatment of vector-borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases. During a 4-year period, from 2009 to 2013, a total number of 551 dog samples were analyzed for vector-borne diseases (borreliosis, babesiosis, ehrlichiosis, anaplasmosis, dirofilariosis, and leishmaniasis) in routine laboratory work. The analysis was done by serological tests - ELISA for borreliosis, dirofilariosis, and leishmaniasis, modified Knott test for dirofilariosis, and blood smear for babesiosis, ehrlichiosis, and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on average more then half of the samples

Chikungunya Virus–Vector Interactions

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Lark L. Coffey

2014-11-01

Full Text Available Chikungunya virus (CHIKV is a mosquito-borne alphavirus that causes chikungunya fever, a severe, debilitating disease that often produces chronic arthralgia. Since 2004, CHIKV has emerged in Africa, Indian Ocean islands, Asia, Europe, and the Americas, causing millions of human infections. Central to understanding CHIKV emergence is knowledge of the natural ecology of transmission and vector infection dynamics. This review presents current understanding of CHIKV infection dynamics in mosquito vectors and its relationship to human disease emergence. The following topics are reviewed: CHIKV infection and vector life history traits including transmission cycles, genetic origins, distribution, emergence and spread, dispersal, vector competence, vector immunity and microbial interactions, and co-infection by CHIKV and other arboviruses. The genetics of vector susceptibility and host range changes, population heterogeneity and selection for the fittest viral genomes, dual host cycling and its impact on CHIKV adaptation, viral bottlenecks and intrahost diversity, and adaptive constraints on CHIKV evolution are also discussed. The potential for CHIKV re-emergence and expansion into new areas and prospects for prevention via vector control are also briefly reviewed.

A generic model for a single strain mosquito-transmitted disease with memory on the host and the vector.

Science.gov (United States)

Sardar, Tridip; Rana, Sourav; Bhattacharya, Sabyasachi; Al-Khaled, Kamel; Chattopadhyay, Joydev

2015-05-01

In the present investigation, three mathematical models on a common single strain mosquito-transmitted diseases are considered. The first one is based on ordinary differential equations, and other two models are based on fractional order differential equations. The proposed models are validated using published monthly dengue incidence data from two provinces of Venezuela during the period 1999-2002. We estimate several parameters of these models like the order of the fractional derivatives (in case of two fractional order systems), the biting rate of mosquito, two probabilities of infection, mosquito recruitment and mortality rates, etc., from the data. The basic reproduction number, R0, for the ODE system is estimated using the data. For two fractional order systems, an upper bound for, R0, is derived and its value is obtained using the published data. The force of infection, and the effective reproduction number, R(t), for the three models are estimated using the data. Sensitivity analysis of the mosquito memory parameter with some important responses is worked out. We use Akaike Information Criterion (AIC) to identify the best model among the three proposed models. It is observed that the model with memory in both the host, and the vector population provides a better agreement with epidemic data. Finally, we provide a control strategy for the vector-borne disease, dengue, using the memory of the host, and the vector. Copyright © 2015 Elsevier Inc. All rights reserved.

Emerging vector borne diseases – incidence through vectors

Directory of Open Access Journals (Sweden)

Sara eSavic

2014-12-01

Full Text Available Vector borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowdays, in intercontinetal countries, there is a struggle with emerging diseases which have found their way to appear through vectors. Vector borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector borne infectious diseases and disease outbreaks. It could affect the range and popultion of pathogens, host and vectors, transmission season, etc. Reliable surveilance for diseases that are most likely to emerge is required. Canine vector borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, erlichiosis, leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fudamental role at primeraly prevention and then treatment of vector borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases.During a four year period, from 2009-2013, a total number of 551 dog samples were analysed for vector borne diseases (borreliosis, babesiosis, erlichiosis, anaplasmosis, dirofilariosis and leishmaniasis in routine laboratory work. The analysis were done by serological tests – ELISA for borreliosis, dirofilariosis and leishmaniasis, modified Knott test for dirofilariosis and blood smear for babesiosis, erlichiosis and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on avarege more then half of the samples

Unraveling Host-Vector-Arbovirus Interactions by Two-Gene High Resolution Melting Mosquito Bloodmeal Analysis in a Kenyan Wildlife-Livestock Interface.

Directory of Open Access Journals (Sweden)

David Omondi

Full Text Available The blood-feeding patterns of mosquitoes are directly linked to the spread of pathogens that they transmit. Efficient identification of arthropod vector bloodmeal hosts can identify the diversity of vertebrate species potentially involved in disease transmission cycles. While molecular bloodmeal analyses rely on sequencing of cytochrome b (cyt b or cytochrome oxidase 1 gene PCR products, recently developed bloodmeal host identification based on high resolution melting (HRM analyses of cyt b PCR products is more cost-effective. To resolve the diverse vertebrate hosts that mosquitoes may potentially feed on in sub-Saharan Africa, we utilized HRM profiles of both cyt b and 16S ribosomal RNA genes. Among 445 blood-fed Aedeomyia, Aedes, Anopheles, Culex, Mansonia, and Mimomyia mosquitoes from Kenya's Lake Victoria and Lake Baringo regions where many mosquito-transmitted pathogens are endemic, we identified 33 bloodmeal hosts including humans, eight domestic animal species, six peridomestic animal species and 18 wildlife species. This resolution of vertebrate host species was only possible by comparing profiles of both cyt b and 16S markers, as melting profiles of some pairs of species were similar for either marker but not both. We identified mixed bloodmeals in a Culex pipiens from Mbita that had fed on a goat and a human and in two Mansonia africana mosquitoes from Baringo that each had fed on a rodent (Arvicanthis niloticus in addition to a human or baboon. We further detected Sindbis and Bunyamwera viruses in blood-fed mosquito homogenates by Vero cell culture and RT-PCR in Culex, Aedeomyia, Anopheles and Mansonia mosquitoes from Baringo that had fed on humans and livestock. The observed mosquito feeding on both arbovirus amplifying hosts (including sheep and goats and possible arbovirus reservoirs (birds, porcupine, baboons, rodents informs arbovirus disease epidemiology and vector control strategies.

Soybean phytase and nucleic acid encoding the same

OpenAIRE

1999-01-01

Isolated soybean phytase polypeptides and isolated nucleic acids encoding soybean phytases are provided. The invention is also directed to nucleic acid expression constructs, vectors, and host cells comprising the isolated soybean phytase nucleic acids, as well as methods for producing recombinant and non-recombinant purified soybean phytase. The invention also relates to transgenic plants expressing the soybean phytase, particularly expression under seed-specific expression control elements.

Bacillus anthracis Overcomes an Amino Acid Auxotrophy by Cleaving Host Serum Proteins

Science.gov (United States)

Terwilliger, Austen; Swick, Michelle C.; Pflughoeft, Kathryn J.; Pomerantsev, Andrei; Lyons, C. Rick; Koehler, Theresa M.

2015-01-01

ABSTRACT Bacteria sustain an infection by acquiring nutrients from the host to support replication. The host sequesters these nutrients as a growth-restricting strategy, a concept termed “nutritional immunity.” Historically, the study of nutritional immunity has centered on iron uptake because many bacteria target hemoglobin, an abundant circulating protein, as an iron source. Left unresolved are the mechanisms that bacteria use to attain other nutrients from host sources, including amino acids. We employed a novel medium designed to mimic the chemical composition of human serum, and we show here that Bacillus anthracis, the causative agent of anthrax disease, proteolyzes human hemoglobin to liberate essential amino acids which enhance its growth. This property can be traced to the actions of InhA1, a secreted metalloprotease, and extends to at least three other serum proteins, including serum albumin. The results suggest that we must also consider proteolysis of key host proteins to be a way for bacterial pathogens to attain essential nutrients, and we provide an experimental framework to determine the host and bacterial factors involved in this process. IMPORTANCE The mechanisms by which bacterial pathogens acquire nutrients during infection are poorly understood. Here we used a novel defined medium that approximates the chemical composition of human blood serum, blood serum mimic (BSM), to better model the nutritional environment that pathogens encounter during bacteremia. Removing essential amino acids from BSM revealed that two of the most abundant proteins in blood—hemoglobin and serum albumin—can satiate the amino acid requirement for Bacillus anthracis, the causative agent of anthrax. We further demonstrate that hemoglobin is proteolyzed by the secreted protease InhA1. These studies highlight that common blood proteins can be a nutrient source for bacteria. They also challenge the historical view that hemoglobin is solely an iron source for

Predation scars may influence host susceptibility to pathogens: evaluating the role of corallivores as vectors of coral disease.

Science.gov (United States)

Nicolet, K J; Chong-Seng, K M; Pratchett, M S; Willis, B L; Hoogenboom, M O

2018-03-27

Infectious diseases not regulated by host density, such as vector-borne diseases, have the potential to drive population declines and extinctions. Here we test the vector potential of the snail Drupella sp. and butterflyfish Chaetodon plebeius for two coral diseases, black band (BBD) and brown band (BrB) disease. Drupella transmitted BrB to healthy corals in 40% of cases immediately following feeding on infected corals, and even in 12% of cases 12 and 24 hours following feeding. However, Drupella was unable to transmit BBD in either transmission treatment. In a field experiment testing the vector potential of naturally-occurring fish assemblages, equivalent numbers of caged and uncaged coral fragments became infected with either BrB, BBD or skeletal eroding band, indicating that corallivorous fish were unlikely to have caused transmission. In aquaria, C. plebeius did not transmit either BBD or BrB, even following extended feeding on both infected and healthy nubbins. A literature review confirmed only four known coral disease vectors, all invertebrates, corroborating our conclusion that polyp-feeding fishes are unlikely to be vectors of coral diseases. This potentially because polyp-feeding fishes produce shallow lesions, not allowing pathogens to invade coral tissues. In contrast, corallivorous invertebrates that create deeper feeding scars increase pathogens transmission.

Vector Differential Calculus

OpenAIRE

HITZER, Eckhard MS

2002-01-01

This paper treats the fundamentals of the vector differential calculus part of universal geometric calculus. Geometric calculus simplifies and unifies the structure and notation of mathematics for all of science and engineering, and for technological applications. In order to make the treatment self-contained, I first compile all important geometric algebra relationships,which are necesssary for vector differential calculus. Then differentiation by vectors is introduced and a host of major ve...

Protein interaction networks at the host-microbe interface in Diaphorina citri, the insect vector of the citrus greening pathogen.

Science.gov (United States)

Ramsey, J S; Chavez, J D; Johnson, R; Hosseinzadeh, S; Mahoney, J E; Mohr, J P; Robison, F; Zhong, X; Hall, D G; MacCoss, M; Bruce, J; Cilia, M

2017-02-01

The Asian citrus psyllid ( Diaphorina citri) is the insect vector responsible for the worldwide spread of ' Candidatus Liberibacter asiaticus' (CLas), the bacterial pathogen associated with citrus greening disease. Developmental changes in the insect vector impact pathogen transmission, such that D. citri transmission of CLas is more efficient when bacteria are acquired by nymphs when compared with adults. We hypothesize that expression changes in the D. citri immune system and commensal microbiota occur during development and regulate vector competency. In support of this hypothesis, more proteins, with greater fold changes, were differentially expressed in response to CLas in adults when compared with nymphs, including insect proteins involved in bacterial adhesion and immunity. Compared with nymphs, adult insects had a higher titre of CLas and the bacterial endosymbionts Wolbachia, Profftella and Carsonella. All Wolbachia and Profftella proteins differentially expressed between nymphs and adults are upregulated in adults, while most differentially expressed Carsonella proteins are upregulated in nymphs. Discovery of protein interaction networks has broad applicability to the study of host-microbe relationships. Using protein interaction reporter technology, a D. citri haemocyanin protein highly upregulated in response to CLas was found to physically interact with the CLas coenzyme A (CoA) biosynthesis enzyme phosphopantothenoylcysteine synthetase/decarboxylase. CLas pantothenate kinase, which catalyses the rate-limiting step of CoA biosynthesis, was found to interact with a D. citri myosin protein. Two Carsonella enzymes involved in histidine and tryptophan biosynthesis were found to physically interact with D. citri proteins. These co-evolved protein interaction networks at the host-microbe interface are highly specific targets for controlling the insect vector responsible for the spread of citrus greening.

Interactive Effects of Southern Rice Black-Streaked Dwarf Virus Infection of Host Plant and Vector on Performance of the Vector, Sogatella furcifera (Homoptera: Delphacidae).

Science.gov (United States)

Lei, Wenbin; Liu, Danfeng; Li, Pei; Hou, Maolin

2014-10-01

Performance of insect vectors can be influenced by the viruses they transmit, either directly by infection of the vectors or indirectly via infection of the host plants. Southern rice black-streaked dwarf virus (SRBSDV) is a propagative virus transmitted by the white-backed planthopper, Sogatella furcifera (Hovath). To elucidate the influence of SRBSDV on the performance of white-backed planthopper, life parameters of viruliferous and nonviruliferous white-backed planthopper fed rice seedlings infected or noninfected with SRBSDV were measured using a factorial design. Regardless of the infection status of the rice plant host, viruliferous white-backed planthopper nymphs took longer to develop from nymph to adult than did nonviruliferous nymphs. Viruliferous white-backed planthopper females deposited fewer eggs than nonviruliferous females and both viruliferous and nonviruliferous white-backed planthopper females laid fewer eggs on infected than on noninfected plants. Longevity of white-backed planthopper females was also affected by the infection status of the rice plant and white-backed planthopper. Nonviruliferous white-backed planthopper females that fed on infected rice plants lived longer than the other three treatment groups. These results indicate that the performance of white-backed planthopper is affected by SRBSDV either directly (by infection of white-backed planthopper) or indirectly (by infection of rice plant). The extended development of viruliferous nymphs and the prolonged life span of nonviruliferous adults on infected plants may increase their likelihood of transmitting virus, which would increase virus spread. © 2014 Entomological Society of America.

Vector population growth and condition-dependent movement drive the spread of plant pathogens.

Science.gov (United States)

Shaw, Allison K; Peace, Angela; Power, Alison G; Bosque-Pérez, Nilsa A

2017-08-01

Plant viruses, often spread by arthropod vectors, impact natural and agricultural ecosystems worldwide. Intuitively, the movement behavior and life history of vectors influence pathogen spread, but the relative contribution of each factor has not been examined. Recent research has highlighted the influence of host infection status on vector behavior and life history. Here, we developed a model to explore how vector traits influence the spread of vector-borne plant viruses. We allowed vector life history (growth rate, carrying capacity) and movement behavior (departure and settlement rates) parameters to be conditional on whether the plant host is infected or healthy and whether the vector is viruliferous (carrying the virus) or not. We ran simulations under a wide range of parameter combinations and quantified the fraction of hosts infected over time. We also ran case studies of the model for Barley yellow dwarf virus, a persistently transmitted virus, and for Potato virus Y, a non-persistently transmitted virus. We quantified the relative importance of each parameter on pathogen spread using Latin hypercube sampling with the statistical partial rank correlation coefficient technique. We found two general types of mechanisms in our model that increased the rate of pathogen spread. First, increasing factors such as vector intrinsic growth rate, carrying capacity, and departure rate from hosts (independent of whether these factors were condition-dependent) led to more vectors moving between hosts, which increased pathogen spread. Second, changing condition-dependent factors such as a vector's preference for settling on a host with a different infection status than itself, and vector tendency to leave a host of the same infection status, led to increased contact between hosts and vectors with different infection statuses, which also increased pathogen spread. Overall, our findings suggest that vector population growth rates had the greatest influence on rates of virus

Eurasian golden jackal as host of canine vector-borne protists.

Science.gov (United States)

Mitková, Barbora; Hrazdilová, Kristýna; D'Amico, Gianluca; Duscher, Georg Gerhard; Suchentrunk, Franz; Forejtek, Pavel; Gherman, Călin Mircea; Matei, Ioana Adriana; Ionică, Angela Monica; Daskalaki, Aikaterini Alexandra; Mihalca, Andrei Daniel; Votýpka, Jan; Hulva, Pavel; Modrý, David

2017-04-14

Jackals are medium-sized canids from the wolf-like clade, exhibiting a unique combination of ancestral morphotypes, broad trophic niches, and close phylogenetic relationships with the wolf and dog. Thus, they represent a potential host of several pathogens with diverse transmission routes. Recently, populations of the Eurasian golden jackal Canis aureus have expanded into the Western Palaearctic, including most of Europe. The aim of our study was to examine Eurasian golden jackals from Romania, Czech Republic and Austria for a wide spectrum of vector-borne protists and to evaluate the role of this species as a reservoir of disease for domestic dogs and/or humans. Diagnostic polymerase chain reaction (PCR) DNA amplifications revealed 70% of jackals to be positive for Hepatozoon, 12.5% positive for piroplasms, and one individual positive for Leishmania infantum. Phylogenetic analyses of partial 18S rDNA sequences invariably placed sequenced isolates of Hepatozoon into the H. canis clade. For piroplasms, both the 18S and cox1 sequences obtained confirmed the presence of Babesia canis and "Theileria annae" in 5 and 2 individuals, respectively, providing the first records of these two piroplasmids in Eurasian golden jackals. A single animal from Dolj County (Romania) was PCR-positive for L. infantum, as confirmed also by sequencing of ITS1-5.8S. Apparently, expanding populations of jackals can play a significant role in spreading and maintaining new Babesia canis foci in Central Europe. The role of jackals in the epidemiology of "Theileria annae" and H. canis is probably similar to that of red foxes and should be taken into account in further research on these parasites. Also the presence of L. infantum deserves attention. Our study confirms that once established, the populations of Eurasian golden jackals constitute natural reservoirs for many canine vector-borne diseases, analogous to the role of the coyotes in North America.

Does host complement kill Borrelia burgdorferi within ticks?

Science.gov (United States)

Rathinavelu, Sivaprakash; Broadwater, Anne; de Silva, Aravinda M

2003-02-01

The Lyme disease spirochete, Borrelia burgdorferi, inhabits the gut lumen of the tick vector. At this location the spirochete is exposed to host blood when a tick feeds. We report here on studies that were done with normal and complement-deficient (C3-knockout) mice to determine if the host complement system killed spirochetes within the vector. We found that spirochete numbers within feeding nymphs were not influenced by complement, most likely because host complement was inactivated within the vector. The Lyme disease outer surface protein A (OspA) vaccine is a transmission-blocking vaccine that targets spirochetes in the vector. In experiments with mice hyperimmunized with OspA, complement was not required to kill spirochetes within nymphs and to block transmission from nymphs to the vaccinated host. However, host complement did enhance the ability of OspA antibody to block larvae from acquiring spirochetes. Thus, the effects of OspA antibody on nymphal transmission and larval acquisition appear to be based on different mechanisms.

Domestic animal hosts strongly influence human-feeding rates of the Chagas disease vector Triatoma infestans in Argentina.

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Ricardo E Gürtler

Full Text Available The host species composition in a household and their relative availability affect the host-feeding choices of blood-sucking insects and parasite transmission risks. We investigated four hypotheses regarding factors that affect blood-feeding rates, proportion of human-fed bugs (human blood index, and daily human-feeding rates of Triatoma infestans, the main vector of Chagas disease.A cross-sectional survey collected triatomines in human sleeping quarters (domiciles of 49 of 270 rural houses in northwestern Argentina. We developed an improved way of estimating the human-feeding rate of domestic T. infestans populations. We fitted generalized linear mixed-effects models to a global model with six explanatory variables (chicken blood index, dog blood index, bug stage, numbers of human residents, bug abundance, and maximum temperature during the night preceding bug catch and three response variables (daily blood-feeding rate, human blood index, and daily human-feeding rate. Coefficients were estimated via multimodel inference with model averaging.Median blood-feeding intervals per late-stage bug were 4.1 days, with large variations among households. The main bloodmeal sources were humans (68%, chickens (22%, and dogs (9%. Blood-feeding rates decreased with increases in the chicken blood index. Both the human blood index and daily human-feeding rate decreased substantially with increasing proportions of chicken- or dog-fed bugs, or the presence of chickens indoors. Improved calculations estimated the mean daily human-feeding rate per late-stage bug at 0.231 (95% confidence interval, 0.157-0.305.Based on the changing availability of chickens in domiciles during spring-summer and the much larger infectivity of dogs compared with humans, we infer that the net effects of chickens in the presence of transmission-competent hosts may be more adequately described by zoopotentiation than by zooprophylaxis. Domestic animals in domiciles profoundly affect the

Construction of Double Right-Border Binary Vector Carrying Non-Host Gene Rxol Resistant to Bacterial Leaf Streak of Rice

Institute of Scientific and Technical Information of China (English)

Xu Mei-rong; XIA Zhi-hui; ZHAI Wen-xue; XU Jian-long; ZHOU Yong-li; LI Zhi-kang

2008-01-01

Rxol cloned from maize is a non-host gene resistant to bacterial leaf streak of rice. pCAMBIA1305-1 with Rxol was digested with Sca Ⅰ and NgoM Ⅳ and the double right-border binary vector pMNDRBBin6 was digested with Hpa Ⅰ and Xma Ⅰ.pMNDRBBin6 carrying the gene Rxol was acquired by ligation of blunt-end and cohesive end. The results of PCR, restriction enzyme analysis and sequencing indicated that the Rxol gene had been cloned into pMNDRBBin6. This double right-border binary vector,named as pMNDRBBin6-Rxol, will play a role in breeding marker-free plants resistant to bacterial leaf streak of rice by genetic transformation.

Tipping the balance: Sclerotinia sclerotiorum secreted oxalic acid suppresses host defenses by manipulating the host redox environment.

Directory of Open Access Journals (Sweden)

Brett Williams

2011-06-01

Full Text Available Sclerotinia sclerotiorum is a necrotrophic ascomycete fungus with an extremely broad host range. This pathogen produces the non-specific phytotoxin and key pathogenicity factor, oxalic acid (OA. Our recent work indicated that this fungus and more specifically OA, can induce apoptotic-like programmed cell death (PCD in plant hosts, this induction of PCD and disease requires generation of reactive oxygen species (ROS in the host, a process triggered by fungal secreted OA. Conversely, during the initial stages of infection, OA also dampens the plant oxidative burst, an early host response generally associated with plant defense. This scenario presents a challenge regarding the mechanistic details of OA function; as OA both suppresses and induces host ROS during the compatible interaction. In the present study we generated transgenic plants expressing a redox-regulated GFP reporter. Results show that initially, Sclerotinia (via OA generates a reducing environment in host cells that suppress host defense responses including the oxidative burst and callose deposition, akin to compatible biotrophic pathogens. Once infection is established however, this necrotroph induces the generation of plant ROS leading to PCD of host tissue, the result of which is of direct benefit to the pathogen. In contrast, a non-pathogenic OA-deficient mutant failed to alter host redox status. The mutant produced hypersensitive response-like features following host inoculation, including ROS induction, callose formation, restricted growth and cell death. These results indicate active recognition of the mutant and further point to suppression of defenses by the wild type necrotrophic fungus. Chemical reduction of host cells with dithiothreitol (DTT or potassium oxalate (KOA restored the ability of this mutant to cause disease. Thus, Sclerotinia uses a novel strategy involving regulation of host redox status to establish infection. These results address a long-standing issue

Cloning vector

Science.gov (United States)

Guilfoyle, Richard A.; Smith, Lloyd M.

1994-01-01

A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.

Cloning vector

Science.gov (United States)

Guilfoyle, R.A.; Smith, L.M.

1994-12-27

A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.

Zika virus, vectors, reservoirs, amplifying hosts, and their potential to spread worldwide: what we know and what we should investigate urgently

Directory of Open Access Journals (Sweden)

Rengina Vorou

2016-07-01

Conclusions: It is a public health imperative to define the domestic and wild animal reservoirs, amplification hosts, and vector capacity of the genera Aedes, Anopheles, and Mansonia. These variables will define the geographic distribution of Zika virus along with the indicated timing and scale of the environmental public health interventions worldwide.

Transient dominant host-range selection using Chinese hamster ovary cells to generate marker-free recombinant viral vectors from vaccinia virus.

Science.gov (United States)

Liu, Liang; Cooper, Tamara; Eldi, Preethi; Garcia-Valtanen, Pablo; Diener, Kerrilyn R; Howley, Paul M; Hayball, John D

2017-04-01

Recombinant vaccinia viruses (rVACVs) are promising antigen-delivery systems for vaccine development that are also useful as research tools. Two common methods for selection during construction of rVACV clones are (i) co-insertion of drug resistance or reporter protein genes, which requires the use of additional selection drugs or detection methods, and (ii) dominant host-range selection. The latter uses VACV variants rendered replication-incompetent in host cell lines by the deletion of host-range genes. Replicative ability is restored by co-insertion of the host-range genes, providing for dominant selection of the recombinant viruses. Here, we describe a new method for the construction of rVACVs using the cowpox CP77 protein and unmodified VACV as the starting material. Our selection system will expand the range of tools available for positive selection of rVACV during vector construction, and it is substantially more high-fidelity than approaches based on selection for drug resistance.

Nestedness of ectoparasite-vertebrate host networks.

Directory of Open Access Journals (Sweden)

Sean P Graham

2009-11-01

Full Text Available Determining the structure of ectoparasite-host networks will enable disease ecologists to better understand and predict the spread of vector-borne diseases. If these networks have consistent properties, then studying the structure of well-understood networks could lead to extrapolation of these properties to others, including those that support emerging pathogens. Borrowing a quantitative measure of network structure from studies of mutualistic relationships between plants and their pollinators, we analyzed 29 ectoparasite-vertebrate host networks--including three derived from molecular bloodmeal analysis of mosquito feeding patterns--using measures of nestedness to identify non-random interactions among species. We found significant nestedness in ectoparasite-vertebrate host lists for habitats ranging from tropical rainforests to polar environments. These networks showed non-random patterns of nesting, and did not differ significantly from published estimates of nestedness from mutualistic networks. Mutualistic and antagonistic networks appear to be organized similarly, with generalized ectoparasites interacting with hosts that attract many ectoparasites and more specialized ectoparasites usually interacting with these same "generalized" hosts. This finding has implications for understanding the network dynamics of vector-born pathogens. We suggest that nestedness (rather than random ectoparasite-host associations can allow rapid transfer of pathogens throughout a network, and expand upon such concepts as the dilution effect, bridge vectors, and host switching in the context of nested ectoparasite-vertebrate host networks.

Adenoviral vector immunity: its implications and circumvention strategies.

Science.gov (United States)

Ahi, Yadvinder S; Bangari, Dinesh S; Mittal, Suresh K

2011-08-01

Adenoviral (Ad) vectors have emerged as a promising gene delivery platform for a variety of therapeutic and vaccine purposes during last two decades. However, the presence of preexisting Ad immunity and the rapid development of Ad vector immunity still pose significant challenges to the clinical use of these vectors. Innate inflammatory response following Ad vector administration may lead to systemic toxicity, drastically limit vector transduction efficiency and significantly abbreviate the duration of transgene expression. Currently, a number of approaches are being extensively pursued to overcome these drawbacks by strategies that target either the host or the Ad vector. In addition, significant progress has been made in the development of novel Ad vectors based on less prevalent human Ad serotypes and nonhuman Ad. This review provides an update on our current understanding of immune responses to Ad vectors and delineates various approaches for eluding Ad vector immunity. Approaches targeting the host and those targeting the vector are discussed in light of their promises and limitations.

Development of plasmid vector and electroporation condition for gene transfer in sporogenic lactic acid bacterium, Bacillus coagulans.

Science.gov (United States)

Rhee, Mun Su; Kim, Jin-Woo; Qian, Yilei; Ingram, L O; Shanmugam, K T

2007-07-01

Bacillus coagulans is a sporogenic lactic acid bacterium that ferments glucose and xylose, major components of plant biomass, a potential feedstock for cellulosic ethanol. The temperature and pH for optimum rate of growth of B. coagulans (50 to 55 degrees C, pH 5.0) are very similar to that of commercially developed fungal cellulases (50 degrees C; pH 4.8). Due to this match, simultaneous saccharification and fermentation (SSF) of cellulose to products by B. coagulans is expected to require less cellulase than needed if the SSF is conducted at a sub-optimal temperature, such as 30 degrees C, the optimum for yeast, the main biocatalyst used by the ethanol industry. To fully exploit B. coagulans as a platform organism, we have developed an electroporation method to transfer plasmid DNA into this genetically recalcitrant bacterium. We also constructed a B. coagulans/E. coli shuttle vector, plasmid pMSR10 that contains the rep region from a native plasmid (pMSR0) present in B. coagulans strain P4-102B. The native plasmid, pMSR0 (6823bp), has 9 ORFs, and replicates by rolling-circle mode of replication. Plasmid pNW33N, developed for Geobacillus stearothermophilus, was also transformed into this host and stably maintained while several other Bacillus/Escherichia coli shuttle vector plasmids were not transformed into B. coagulans. The transformation efficiency of B. coagulans strain P4-102B using the plasmids pNW33N or pMSR10 was about 1.5x10(16) per mole of DNA. The availability of shuttle vectors and an electroporation method is expected to aid in genetic and metabolic engineering of B. coagulans.

Malaria-induced changes in host odors enhance mosquito attraction.

Science.gov (United States)

De Moraes, Consuelo M; Stanczyk, Nina M; Betz, Heike S; Pulido, Hannier; Sim, Derek G; Read, Andrew F; Mescher, Mark C

2014-07-29

Vector-borne pathogens may alter traits of their primary hosts in ways that influence the frequency and nature of interactions between hosts and vectors. Previous work has reported enhanced mosquito attraction to host organisms infected with malaria parasites but did not address the mechanisms underlying such effects. Here we document malaria-induced changes in the odor profiles of infected mice (relative to healthy individuals) over the course of infection, as well as effects on the attractiveness of infected hosts to mosquito vectors. We observed enhanced mosquito attraction to infected mice during a key period after the subsidence of acute malaria symptoms, but during which mice remained highly infectious. This attraction corresponded to an overall elevation in the volatile emissions of infected mice observed during this period. Furthermore, data analyses--using discriminant analysis of principal components and random forest approaches--revealed clear differences in the composition of the volatile blends of infected and healthy individuals. Experimental manipulation of individual compounds that exhibited altered emission levels during the period when differential vector attraction was observed also elicited enhanced mosquito attraction, indicating that compounds being influenced by malaria infection status also mediate vector host-seeking behavior. These findings provide important insights into the cues that mediate vector attraction to hosts infected with transmissible stages of malaria parasites, as well as documenting characteristic changes in the odors of infected individuals that may have potential value as diagnostic biomarkers of infection.

Host-feeding patterns of Culex pipiens and other potential mosquito vectors (Diptera: Culicidae) of West Nile virus (Flaviviridae) collected in Portugal.

Science.gov (United States)

Osório, Hugo Costa; Zé-Zé, Líbia; Alves, Maria João

2012-05-01

The host blood-feeding patterns of mosquito vectors affects the likelihood of human exposure to zoonotic pathogens, including West Nile Virus (family Flaviviridae, genus Flavivirus, WNV). In Portugal, data are unavailable regarding the blood-feeding habits of common mosquito species, including Culex pipiens L., considered the primary vector of WNV to humans. The sources of bloodmeals in 203 blood-fed mosquitoes of nine species collected from June 2007 to November 2010 in 34 Portuguese counties were analyzed by sequencing cytochrome-b partial fragments. Cx. pipiens was the most common species collected and successfully analyzed (n = 135/78). In addition, blood-fed females of the following species were analyzed: Ochlerotatus caspius Pallas (n = 20), Culex theileri Theobald (n = 16), Anopheles maculipennis s.l. Meigen (n = 10), Culiseta longiareolata Macquart (n = 7), Aedes aegypti L. (n = 6), Culex perexiguus Theobald (n = 3), Culiseta annulata Schrank (n = 3), and Ochlerotatus detritus Haliday (n = 3). The Cx. pipiens mosquitoes fed predominantly on birds (n = 55/78, 70.5%), with a high diversity of avian species used as hosts, although human blood was identified in 18 specimens (18/78, 23.1%). No significant differences were found between the host-feeding patterns of blood-fed Cx. pipiens collected in residential and nonresidential habitats. The occurrence of human derived blood meals and the presence of a mix avian-human bloodmeal accordingly suggest this species as a potential vector of WNV. Therefore, in Portugal, Cx. pipiens may play a role both in the avian-to-avian enzootic WNV cycle and in the avian-to-mammal transmission. In this context, the identity of Cx. pipiens (considering the forms molestus and pipiens) and the potential consequence on feeding behavior and WNV transmission are discussed.

Molecular crosstalks in Leishmania-sandfly-host relationships

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Volf P.

2008-09-01

Full Text Available Sandflies (Diptera: Phlebotominae are vectors of Leishmania parasites, causative agents of important human and animal diseases with diverse manifestations. This review summarizes present knowledge about the vectorial part of Leishmania life cycle and parasite transmission to the vertebrate host. Particularly, it focuses on molecules that determine the establishment of parasite infection in sandfly midgut. It describes the concept of specific versus permissive sandfly vectors, explains the epidemiological consequences of broad susceptibility of permissive sandflies and demonstrates that genetic exchange may positively affect Leishmania fitness in the vector. Last but not least, the review describes recent knowledge about circulating antibodies produced by hosts in response to sandfly bites. Studies on specificity and kinetics of antibody response revealed that anti-saliva IgG could be used as a marker of host exposure to sandflies, i.e. as a useful tool for evaluation of vector control.

Local host specialization, host-switching, and dispersal shape the regional distributions of avian haemosporidian parasites.

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Ellis, Vincenzo A; Collins, Michael D; Medeiros, Matthew C I; Sari, Eloisa H R; Coffey, Elyse D; Dickerson, Rebecca C; Lugarini, Camile; Stratford, Jeffrey A; Henry, Donata R; Merrill, Loren; Matthews, Alix E; Hanson, Alison A; Roberts, Jackson R; Joyce, Michael; Kunkel, Melanie R; Ricklefs, Robert E

2015-09-08

The drivers of regional parasite distributions are poorly understood, especially in comparison with those of free-living species. For vector-transmitted parasites, in particular, distributions might be influenced by host-switching and by parasite dispersal with primary hosts and vectors. We surveyed haemosporidian blood parasites (Plasmodium and Haemoproteus) of small land birds in eastern North America to characterize a regional parasite community. Distributions of parasite populations generally reflected distributions of their hosts across the region. However, when the interdependence between hosts and parasites was controlled statistically, local host assemblages were related to regional climatic gradients, but parasite assemblages were not. Moreover, because parasite assemblage similarity does not decrease with distance when controlling for host assemblages and climate, parasites evidently disperse readily within the distributions of their hosts. The degree of specialization on hosts varied in some parasite lineages over short periods and small geographic distances independently of the diversity of available hosts and potentially competing parasite lineages. Nonrandom spatial turnover was apparent in parasite lineages infecting one host species that was well-sampled within a single year across its range, plausibly reflecting localized adaptations of hosts and parasites. Overall, populations of avian hosts generally determine the geographic distributions of haemosporidian parasites. However, parasites are not dispersal-limited within their host distributions, and they may switch hosts readily.

Production of lentiviral vectors

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Otto-Wilhelm Merten

2016-01-01

Full Text Available Lentiviral vectors (LV have seen considerably increase in use as gene therapy vectors for the treatment of acquired and inherited diseases. This review presents the state of the art of the production of these vectors with particular emphasis on their large-scale production for clinical purposes. In contrast to oncoretroviral vectors, which are produced using stable producer cell lines, clinical-grade LV are in most of the cases produced by transient transfection of 293 or 293T cells grown in cell factories. However, more recent developments, also, tend to use hollow fiber reactor, suspension culture processes, and the implementation of stable producer cell lines. As is customary for the biotech industry, rather sophisticated downstream processing protocols have been established to remove any undesirable process-derived contaminant, such as plasmid or host cell DNA or host cell proteins. This review compares published large-scale production and purification processes of LV and presents their process performances. Furthermore, developments in the domain of stable cell lines and their way to the use of production vehicles of clinical material will be presented.

Vector borne diseases

OpenAIRE

Melillo Fenech, Tanya

2010-01-01

A vector-borne disease is one in which the pathogenic microorganism is transmitted from an infected individual to another individual by an arthropod or other agent. The transmission depends upon the attributes and requirements of at least three different Iiving organisms : the pathologic agent which is either a virus, protozoa, bacteria or helminth (worm); the vector, which is commonly an arthropod such as ticks or mosquitoes; and the human host.

Does Host Complement Kill Borrelia burgdorferi within Ticks?

OpenAIRE

Rathinavelu, Sivaprakash; Broadwater, Anne; de Silva, Aravinda M.

2003-01-01

The Lyme disease spirochete, Borrelia burgdorferi, inhabits the gut lumen of the tick vector. At this location the spirochete is exposed to host blood when a tick feeds. We report here on studies that were done with normal and complement-deficient (C3-knockout) mice to determine if the host complement system killed spirochetes within the vector. We found that spirochete numbers within feeding nymphs were not influenced by complement, most likely because host complement was inactivated within ...

Alternation of host plants as a survival mechanism of leafhoppers Dilobopterus costalimai and Oncometopia facialis (Hemiptera: Cicadellidae, vectors of the Citrus Variegated Chlorosis (CVC

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Milanez José Maria

2001-01-01

Full Text Available Dilobopterus costalimai (Young and Oncometopia facialis (Signoret are two of the most important species of citrus leafhoppers, vectors of bacterium Xylella fastidiosa which causes the Citrus Variegated Chlorosis (CVC disease. To develop a rearing technique for these species under laboratory conditions, the egg laying preference and nymph development were studied in different breeding systems: Rangpur lime (Citrus limonia and "falso boldo" (Vernonia condensata as host plants. Trials were set up in a randomized block design with three treatments (n=8. Females of D. costalimai had particular preference for ovipositing on Rangpur lime leaves while O. facialis females placed a higher number of eggs on "falso boldo", but it did not differ statistically from the Rangpur lime. The nymphal viability of D. costalimai was null in Rangpur lime and 58% in "falso boldo". For O. facialis the nymphal viability was 25 and 78% in Rangpur lime and "falso boldo", respectively. "Falso boldo" is more suitable as a host plant to rear the two species of citrus leafhoppers. The alternation of host plants seems to be an important survival mechanism of the CVC-vector species, as shown in natural conditions.

Plant Virus–Insect Vector Interactions: Current and Potential Future Research Directions

Science.gov (United States)

Dietzgen, Ralf G.; Mann, Krin S.; Johnson, Karyn N.

2016-01-01

Acquisition and transmission by an insect vector is central to the infection cycle of the majority of plant pathogenic viruses. Plant viruses can interact with their insect host in a variety of ways including both non-persistent and circulative transmission; in some cases, the latter involves virus replication in cells of the insect host. Replicating viruses can also elicit both innate and specific defense responses in the insect host. A consistent feature is that the interaction of the virus with its insect host/vector requires specific molecular interactions between virus and host, commonly via proteins. Understanding the interactions between plant viruses and their insect host can underpin approaches to protect plants from infection by interfering with virus uptake and transmission. Here, we provide a perspective focused on identifying novel approaches and research directions to facilitate control of plant viruses by better understanding and targeting virus–insect molecular interactions. We also draw parallels with molecular interactions in insect vectors of animal viruses, and consider technical advances for their control that may be more broadly applicable to plant virus vectors. PMID:27834855

Herbivore arthropods benefit from vectoring plant viruses

NARCIS (Netherlands)

Belliure, B.; Janssen, A.; Maris, P.C.; Peters, D.; Sabelis, M.W.

2005-01-01

Plants infected with pathogens often attract the pathogens' vectors, but it is not clear if this is advantageous to the vectors. We therefore quantified the direct and indirect (through the host plant) effects of a pathogen on its vector. A positive direct effect of the plant-pathogenic Tomato

Effects of Non-Susceptible Hosts on the Infection with Trypanosoma cruzi of the Vector Triatoma infestans: an Experimental Model

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Vázquez Diego P

1999-01-01

Full Text Available We tested experimentally the effects of the presence of non-susceptible hosts on the infection with Trypanosoma cruzi of the vector Triatoma infestans. The experiment consisted in two treatments: with chickens, including two chickens (non-susceptible hosts and two infected guinea pigs (susceptible hosts, and without chickens, including only two infected guinea pigs. The hosts were held unrestrained in individual metal cages inside a closed tulle chamber. A total of 200 uninfected T. infestans third instar nymphs were liberated in each replica, collected on day 14, and examined for infection and blood meal sources on day 32-36. The additional presence of chickens relative to infected guinea pigs: (a significantly modified the spatial distribution of bugs; (b increased significantly the likelihoods of having a detectable blood meal on any host and molting to the next instar; (c did not affect the bugs' probability of death by predation; and (d decreased significantly the overall percentage of T. infestans infected with T. cruzi. The bugs collected from inside or close to the guinea pigs' cages showed a higher infection rate (71-88% than those collected from the chickens' cages (22-32%. Mixed blood meals on chickens and guinea pigs were detected in 12-21% of bugs. Although the presence of chickens would decrease the overall percentage of infected bugs in short term experiments, the high rate of host change of T. infestans would make this difference fade out if longer exposure times had been provided.

Analytic calculation of finite-population reproductive numbers for direct- and vector-transmitted diseases with homogeneous mixing.

Science.gov (United States)

Keegan, Lindsay; Dushoff, Jonathan

2014-05-01

The basic reproductive number, R0, provides a foundation for evaluating how various factors affect the incidence of infectious diseases. Recently, it has been suggested that, particularly for vector-transmitted diseases, R0 should be modified to account for the effects of finite host population within a single disease transmission generation. Here, we use a transmission factor approach to calculate such "finite-population reproductive numbers," under the assumption of homogeneous mixing, for both vector-borne and directly transmitted diseases. In the case of vector-borne diseases, we estimate finite-population reproductive numbers for both host-to-host and vector-to-vector generations, assuming that the vector population is effectively infinite. We find simple, interpretable formulas for all three of these quantities. In the direct case, we find that finite-population reproductive numbers diverge from R0 before R0 reaches half of the population size. In the vector-transmitted case, we find that the host-to-host number diverges at even lower values of R0, while the vector-to-vector number diverges very little over realistic parameter ranges.

Can antibodies against flies alter malaria transmission in birds by changing vector behavior?

Science.gov (United States)

Ghosh, Suma; Waite, Jessica L; Clayton, Dale H; Adler, Frederick R

2014-10-07

Transmission of insect-borne diseases is shaped by the interactions among parasites, vectors, and hosts. Any factor that alters movement of infected vectors from infected to uninfeced hosts will in turn alter pathogen spread. In this paper, we study one such pathogen-vector-host system, avian malaria in pigeons transmitted by fly ectoparasites, where both two-way and three-way interactions play a key role in shaping disease spread. Bird immune defenses against flies can decrease malaria prevalence by reducing fly residence time on infected birds or increase disease prevalence by enhancing fly movement and thus infection transmission. We develop a mathematical model that illustrates how these changes in vector behavior influence pathogen transmission and show that malaria prevalence is maximized at an intermediate level of defense avoidance by the flies. Understanding how host immune defenses indirectly alter disease transmission by influencing vector behavior has implications for reducing the transmission of human malaria and other vectored pathogens. Published by Elsevier Ltd.

Protecting cows in small holder farms in East Africa from tsetse flies by mimicking the odor profile of a non-host bovid.

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Rajinder K Saini

2017-10-01

Full Text Available For the first time, differential attraction of pathogen vectors to vertebrate animals is investigated for novel repellents which when applied to preferred host animals turn them into non-hosts thereby providing a new paradigm for innovative vector control. For effectively controlling tsetse flies (Glossina spp., vectors of African trypanosomosis, causing nagana, repellents more powerful than plant derived, from a non-host animal the waterbuck, Kobus ellipsiprymnus defassa, have recently been identified. Here we investigate these repellents in the field to protect cattle from nagana by making cattle as unattractive as the buck.To dispense the waterbuck repellents comprising guaiacol, geranylacetone, pentanoic acid and δ-octalactone, (patent application we developed an innovative collar-mounted release system for individual cattle. We tested protecting cattle, under natural tsetse challenge, from tsetse transmitted nagana in a large field trial comprising 1,100 cattle with repellent collars in Kenya for 24 months. The collars provided substantial protection to livestock from trypanosome infection by reducing disease levels >80%. Protected cattle were healthier, showed significantly reduced disease levels, higher packed cell volume and significantly increased weight. Collars >60% reduced trypanocide use, 72.7% increase in ownership of oxen per household and enhanced traction power (protected animals ploughed 66% more land than unprotected. Land under cultivation increased by 73.4%. Increase in traction power of protected animals reduced by 69.1% acres tilled by hand per household per ploughing season. Improved food security and household income from very high acceptance of collars (99% motivated the farmers to form a registered community based organization promoting collars for integrated tsetse control and their commercialization.Clear demonstration that repellents from un-preferred hosts prevent contact between host and vector, thereby

Host and Potential Vector Susceptibility to an Emerging Orbivirus in the United States: Epizootic Hemorrhagic Disease Virus Serotype 6.

Science.gov (United States)

Ruder, M G; Stallknecht, D E; Allison, A B; Mead, D G; Carter, D L; Howerth, E W

2016-05-01

Epizootic hemorrhagic disease viruses (EHDVs) are orbiviruses transmitted by Culicoides biting midges to domestic and wild ruminants. EHDV-1 and EHDV-2 are endemic in the United States, where epizootic hemorrhagic disease is the most significant viral disease of white-tailed deer (WTD;Odocoileus virginianus) and reports of epizootic hemorrhagic disease in cattle are increasing. In 2006, a reassortant EHDV-6 was isolated from dead WTD in Indiana and has been detected each subsequent year over a wide geographic region. Since EHDV-6 is not a historically endemic serotype in the United States, it is important to understand infection outcome in potential hosts. Specifically, we aimed to evaluate the pathogenicity of the virus in 2 primary US ruminant hosts (WTD and cattle) and the susceptibility of a confirmed US vector (Culicoides sonorensis). Five WTD and 4 cattle were inoculated with >10(6)TCID50EHDV-6 by intradermal and subcutaneous injection. All 5 WTD exhibited moderate to severe disease, and 3 died. Viremia was first detected 3 to 5 days postinfection (dpi) with surviving animals seroconverting by 10 dpi. Two of 4 inoculated cattle had detectable viremia, 5 to 10 dpi and 7 to 24 dpi, respectively. No clinical, hematologic, or pathologic abnormalities were observed. Antibodies were detected by 10 dpi in 3 of 4 cows.C. sonorensis were fed on WTD blood spiked with EHDV-6 and held for 4 to 14 days postfeeding at 25°C. From 4 to 14 days postfeeding, 19 of 171 midges were virus isolation positive and 6 of 171 had ≥10(2.7)TCID50EHDV-6. Although outcomes varied, these studies demonstrate the susceptibility of ruminant and vector hosts in the United States for this recently emerged EHDV serotype. © The Author(s) 2015.

Geographic range of vector-borne infections and their vectors: the role of African wildlife.

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van Vuuren, M; Penzhorn, B L

2015-04-01

The role of African wildlife in the occurrence of vector-borne infections in domestic animals has gained renewed interest as emerging and re-emerging infections occur worldwide at an increasing rate. In Africa, biodiversity conservation and the expansion of livestock production have increased the risk of transmitting vector-borne infections between wildlife and livestock. The indigenous African pathogens with transboundary potential, such as Rift Valley fever virus, African horse sickness virus, bluetongue virus, lumpy skin disease virus, African swine fever virus, and blood-borne parasites have received the most attention. There is no evidence for persistent vector-borne viral infections in African wildlife. For some viral infections, wildlife may act as a reservoir through the inter-epidemic circulation of viruses with mild or subclinical manifestations. Wildlife may also act as introductory or transporting hosts when moved to new regions, e.g. for lumpy skin disease virus, Rift Valley fever virus and West Nile virus. Wildlife may also act as amplifying hosts when exposed to viruses in the early part of the warm season when vectors are active, with spillover to domestic animals later in the season, e.g. with bluetongue and African horse sickness. Some tick species found on domestic animals are more abundant on wildlife hosts; some depend on wildlife hosts to complete their life cycle. Since the endemic stability of a disease depends on a sufficiently large tick population to ensure that domestic animals become infected at an early age, the presence of wildlife hosts that augment tick numbers may be beneficial. Many wild ungulate species are reservoirs of Anaplasma spp., while the role of wildlife in the epidemiology of heartwater (Ehrlichia ruminantium infection) has not been elucidated. Wild ungulates are not usually reservoirs of piroplasms that affect livestock; however, there are two exceptions: zebra, which are reservoirs of Babesia caballi and Theileria

Virus infection of a weed increases vector attraction to and vector fitness on the weed.

Science.gov (United States)

Chen, Gong; Pan, Huipeng; Xie, Wen; Wang, Shaoli; Wu, Qingjun; Fang, Yong; Shi, Xiaobin; Zhang, Youjun

2013-01-01

Weeds are important in the ecology of field crops, and when crops are harvested, weeds often become the main hosts for plant viruses and their insect vectors. Few studies, however, have examined the relationships between plant viruses, vectors, and weeds. Here, we investigated how infection of the weed Datura stramonium L. by tomato yellow leaf curl virus (TYLCV) affects the host preference and performance of the TYLCV vector, Bemisia tabaci (Gennadius) Q. The results of a choice experiment indicated that B. tabaci Q preferentially settled and oviposited on TYLCV-infected plants rather than on healthy plants. In addition, B. tabaci Q performed better on TYLCV-infected plants than on healthy plants. These results demonstrate that TYLCV is indirectly mutualistic to B. tabaci Q. The mutually beneficial interaction between TYLCV and B. tabaci Q may help explain the concurrent outbreaks of TYLCV and B. tabaci Q in China.

Host feeding pattern of Japanese encephalitis virus vector mosquitoes (Diptera: Culicidae) from Kuttanadu, Kerala, India.

Science.gov (United States)

Philip Samuel, P; Arunachalam, N; Hiriyan, J; Tyagi, B K

2008-09-01

Identification of blood meals of vector mosquitoes is an important tool in the epidemiological investigations of vector-borne diseases. The blood meals of three mosquito species involved in the transmission of Japanese encephalitis virus (JEV) from the Kuttanadu area, Kerala, were determined using the agarose gel diffusion technique. A total of 4959 blood smears belonging to Culex (Culex) tritaeniorhynchus Giles (3273), Cx. (Culex) gelidus Theobald (64), Mansonia (Mnd.) indiana Edwards (735) ,and Ma. (Mnd.) uniformis (Theobald) (887) were tested. Cx. tritaeniorhynchus had predominantly fed on bovids (46.4%), and a good proportion (29%) had fed on more than one host. Cx. tritaeniorhynchus was highly zoophagic, and human feeding accounted for only 1.5% of those individuals successfully tested. Cx. gelidus showed bovid feeding at 36% and pig feeding at 12.5%. The test results showed 42.3% Ma. indiana and 12.2% Ma. uniformis had fed on humans. Multiple feeding was observed in Ma. indiana and Ma. uniformis, and most of the double feedings were from bovids and ovids (7.9 and 20.1%, respectively). Pig feeding accounted for 4.8% of the feedings by Cx. tritaeniorhynchus, 5.3% of Ma. indiana, and 6.4% of Ma. uniformis. This study is significant because of the role played by these mosquitoes in the transmission of JEV in the Kuttanadu area of Kerala, India.

Calanus spp.-Vectors for the biotoxin, domoic acid, in the Arctic marine ecosystem?

DEFF Research Database (Denmark)

Tammilehto, A.; Nielsen, Torkel Gissel; Krock, B.

2012-01-01

Three Calanus species, Calanus glacialis, Calanus finmarchicus and Calanus hyperboreus, which are the most important zooplankton herbivores in Western Greenland, were fed with unialgal cultures of toxic Pseudo-nitzschia seriata and non-toxic Pseudo-nitzschia delicatissima. All three copepod speci...... are potential vectors for domoic acid to higher trophic levels in the Arctic...... cell quota of P. seriata during the experiment on C. glacialis than on the other two copepod species. The depuration experiment on C. glacialis indicated that the copepods still retained domoic acid after 10 h of depuration in filtered sea water. The results show that the three Calanus species...

Dataset on usnic acid from Cladonia substellata Vainio (Lichen) schistosomiasis mansoni's vector control and environmental toxicity.

Science.gov (United States)

Andrade de Araújo, Hallysson Douglas; Dos Santos Silva, Luanna Ribeiro; de Siqueira, Williams Nascimento; Martins da Fonseca, Caíque Silveira; da Silva, Nicácio Henrique; de Albuquerque Melo, Ana Maria Mendonça; Barroso Martins, Mônica Cristina; de Menezes Lima, Vera Lúcia

2018-04-01

This text presents complementary data corresponding to schistosomiasis mansoni's vector control and enviromental toxicity using usnic acid. These informations support our research article "Toxicity of Usnic Acid from Cladonia substellata (Lichen) to embryos and adults of Biomphalaria glabrata " by Araújo et al. [1], and focuses on the analysis of the detailed data regarding the different concentrations of Usnic Acid and their efficiency to B. glabrata mortality and non-viability, as also to environmental toxicity, evaluated by A. salina mortality.

An efficient viral vector for functional genomic studies of Prunus fruit trees and its induced resistance to Plum pox virus via silencing of a host factor gene.

Science.gov (United States)

Cui, Hongguang; Wang, Aiming

2017-03-01

RNA silencing is a powerful technology for molecular characterization of gene functions in plants. A commonly used approach to the induction of RNA silencing is through genetic transformation. A potent alternative is to use a modified viral vector for virus-induced gene silencing (VIGS) to degrade RNA molecules sharing similar nucleotide sequence. Unfortunately, genomic studies in many allogamous woody perennials such as peach are severely hindered because they have a long juvenile period and are recalcitrant to genetic transformation. Here, we report the development of a viral vector derived from Prunus necrotic ringspot virus (PNRSV), a widespread fruit tree virus that is endemic in all Prunus fruit production countries and regions in the world. We show that the modified PNRSV vector, harbouring the sense-orientated target gene sequence of 100-200 bp in length in genomic RNA3, could efficiently trigger the silencing of a transgene or an endogenous gene in the model plant Nicotiana benthamiana. We further demonstrate that the PNRSV-based vector could be manipulated to silence endogenous genes in peach such as eukaryotic translation initiation factor 4E isoform (eIF(iso)4E), a host factor of many potyviruses including Plum pox virus (PPV). Moreover, the eIF(iso)4E-knocked down peach plants were resistant to PPV. This work opens a potential avenue for the control of virus diseases in perennial trees via viral vector-mediated silencing of host factors, and the PNRSV vector may serve as a powerful molecular tool for functional genomic studies of Prunus fruit trees. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Protein expression vector and secretion signal peptide optimization to drive the production, secretion, and functional expression of the bacteriocin enterocin A in lactic acid bacteria.

Science.gov (United States)

Borrero, Juan; Jiménez, Juan J; Gútiez, Loreto; Herranz, Carmen; Cintas, Luis M; Hernández, Pablo E

2011-10-20

Replacement of the leader sequence (LS) of the bacteriocin enterocin A (LS(entA)) by the signal peptides (SP) of the protein Usp45 (SP(usp45)), and the bacteriocins enterocin P (SP(entP)), and hiracin JM79 (SP(hirJM79)) permits the production, secretion, and functional expression of EntA by different lactic acid bacteria (LAB). Chimeric genes encoding the SP(usp45), the SP(entP), and the SP(hirJM79) fused to mature EntA plus the EntA immunity genes (entA+entiA) were cloned into the expression vectors pNZ8048 and pMSP3545, under control of the inducible P(nisA) promoter, and in pMG36c, under control of the constitutive P(32) promoter. The amount, antimicrobial activity, and specific antimicrobial activity of the EntA produced by the recombinant Lactococcus lactis, Enterococcus faecium, E. faecalis, Lactobacillus sakei and Pediococcus acidilactici hosts varied depending on the signal peptide, the expression vector, and the host strain. However, the antimicrobial activity and the specific antimicrobial activity of the EntA produced by most of the LAB transformants was lower than expected from their production. The supernatants of the recombinant L. lactis NZ9000 (pNZUAI) and L. lactis NZ9000 (pNZHAI), overproducers of EntA, showed a 1.2- to 5.1-fold higher antimicrobial activity than that of the natural producer E. faecium T136 against different Listeria spp. Copyright © 2011 Elsevier B.V. All rights reserved.

Staphylococcus aureus utilizes host-derived lipoprotein particles as sources of exogenous fatty acids.

Science.gov (United States)

Delekta, Phillip C; Shook, John C; Lydic, Todd A; Mulks, Martha H; Hammer, Neal D

2018-03-26

Methicillin-resistant Staphylococcus aureus (MRSA) is a threat to global health. Consequently, much effort has focused on the development of new antimicrobials that target novel aspects of S. aureus physiology. Fatty acids are required to maintain cell viability, and bacteria synthesize fatty acids using the type II fatty acid synthesis pathway (FASII). FASII is significantly different from human fatty acid synthesis, underscoring the therapeutic potential of inhibiting this pathway. However, many Gram-positive pathogens incorporate exogenous fatty acids, bypassing FASII inhibition and leaving the clinical potential of FASII inhibitors uncertain. Importantly, the source(s) of fatty acids available to pathogens within the host environment remains unclear. Fatty acids are transported throughout the body by lipoprotein particles in the form of triglycerides and esterified cholesterol. Thus, lipoproteins, such as low-density lipoprotein (LDL) represent a potentially rich source of exogenous fatty acids for S. aureus during infection. We sought to test the ability of LDLs to serve as a fatty acid source for S. aureus and show that cells cultured in the presence of human LDLs demonstrate increased tolerance to the FASII inhibitor, triclosan. Using mass spectrometry, we observed that host-derived fatty acids present in the LDLs are incorporated into the staphylococcal membrane and that tolerance to triclosan is facilitated by the fatty acid kinase A, FakA, and Geh, a triacylglycerol lipase. Finally, we demonstrate that human LDLs support the growth of S. aureus fatty acid auxotrophs. Together, these results suggest that human lipoprotein particles are a viable source of exogenous fatty acids for S. aureus during infection. IMPORTANCE Inhibition of bacterial fatty acid synthesis is a promising approach to combating infections caused by S. aureus and other human pathogens. However, S. aureus incorporates exogenous fatty acids into its phospholipid bilayer. Therefore, the

Free amino acids exhibit anthozoan "host factor" activity: they induce the release of photosynthate from symbiotic dinoflagellates in vitro.

Science.gov (United States)

Gates, R D; Hoegh-Guldberg, O; McFall-Ngai, M J; Bil, K Y; Muscatine, L

1995-08-01

Reef-building corals and other tropical anthozoans harbor endosymbiotic dinoflagellates. It is now recognized that the dinoflagellates are fundamental to the biology of their hosts, and their carbon and nitrogen metabolisms are linked in important ways. Unlike free living species, growth of symbiotic dinoflagellates is unbalanced and a substantial fraction of the carbon fixed daily by symbiont photosynthesis is released and used by the host for respiration and growth. Release of fixed carbon as low molecular weight compounds by freshly isolated symbiotic dinoflagellates is evoked by a factor (i.e., a chemical agent) present in a homogenate of host tissue. We have identified this "host factor" in the Hawaiian coral Pocillopora damicornis as a set of free amino acids. Synthetic amino acid mixtures, based on the measured free amino acid pools of P. damicornis tissues, not only elicit the selective release of 14C-labeled photosynthetic products from isolated symbiotic dinoflagellates but also enhance total 14CO2 fixation.

Hexon-chimaeric adenovirus serotype 5 vectors circumvent pre-existing anti-vector immunity

NARCIS (Netherlands)

Roberts, Diane M.; Nanda, Anjali; Havenga, Menzo J. E.; Abbink, Peter; Lynch, Diana M.; Ewald, Bonnie A.; Liu, Jinyan; Thorner, Anna R.; Swanson, Patricia E.; Gorgone, Darci A.; Lifton, Michelle A.; Lemckert, Angelique A. C.; Holterman, Lennart; Chen, Bing; Dilraj, Athmanundh; Carville, Angela; Mansfield, Keith G.; Goudsmit, Jaap; Barouch, Dan H.

2006-01-01

A common viral immune evasion strategy involves mutating viral surface proteins in order to evade host neutralizing antibodies. Such immune evasion tactics have not previously been intentionally applied to the development of novel viral gene delivery vectors that overcome the critical problem of

[Effects of plant viruses on vector and non-vector herbivorous arthropods and their natural enemies: a mini review].

Science.gov (United States)

He, Xiao-Chan; Xu, Hong-Xing; Zhou, Xiao-Jun; Zheng, Xu-Song; Sun, Yu-Jian; Yang, Ya-Jun; Tian, Jun-Ce; Lü, Zhong-Xian

2014-05-01

Plant viruses transmitted by arthropods, as an important biotic factor, may not only directly affect the yield and quality of host plants, and development, physiological characteristics and ecological performances of their vector arthropods, but also directly or indirectly affect the non-vector herbivorous arthropods and their natural enemies in the same ecosystem, thereby causing influences to the whole agro-ecosystem. This paper reviewed the progress on the effects of plant viruses on herbivorous arthropods, including vector and non-vector, and their natural enemies, and on their ecological mechanisms to provide a reference for optimizing the management of vector and non-vector arthropod populations and sustainable control of plant viruses in agro-ecosystem.

Escaping deleterious immune response in their hosts: lessons from trypanosomatids

Directory of Open Access Journals (Sweden)

Anne eGeiger

2016-05-01

Full Text Available The Trypanosomatidae family includes the genera Trypanosoma and Leishmania, protozoan parasites displaying complex digenetic life cycles requiring a vertebrate host and an insect vector. Trypanosoma brucei gambiense, T. cruzi and Leishmania spp are important human pathogens causing Human African Trypanosomiasis (HAT or Sleeping Sickness, Chagas’ disease, and various clinical forms of Leishmaniasis, respectively. They are transmitted to humans by tsetse flies, triatomine bugs or sandflies and affect millions of people worldwide.In humans, extracellular African trypanosomes (T. brucei evade the hosts’ immune defences, allowing their transmission to the next host, via the tsetse vector. By contrast, T. cruzi and Leishmania sp. have developed a complex intracellular lifestyle, also preventing several mechanisms to circumvent the host’s immune response.This review seeks to set out the immune evasion strategies developed by the different trypanosomatids resulting from parasite-host interactions and, will focus on: clinical and epidemiological importance of diseases; life cycles: parasites-hosts-vectors; innate immunity: key steps for trypanosomatids in invading hosts; deregulation of antigen presenting cells; disruption of efficient specific immunity; and the immune responses used for parasite proliferation.

Schistosoma mansoni: assessment of effects of oleic acid, cercarial age and water temperature on parasite-host attraction.

Science.gov (United States)

Lee, Vivien S T; Burgess, Jefferey L; Sterling, Charles R; Lutz, Eric A

2013-09-01

Although the lifecycle of Schistosoma spp. and pathophysiology of schistosomiasis have been established, the mechanism by which cercariae find their host is not well understood. Speculatively, host infection by random and accidental host contact is not as biologically plausible as a biochemical mechanism of mammalian attraction. A few studies have indicated that biochemical cues and temperature gradients may play a role in host identification, attraction and attachment triggers. This study aimed to elucidate these mechanisms more specifically through evaluation of biochemical, age and temperature influences leading to Schistosoma mansoni cercariae attraction and attachment behaviors. Oleic acid, a common unsaturated free fatty acid in the outer layer of human skin, was tested for cercariae attraction across biologically relevant concentrations. Influence of media type (beeswax, nail varnish and agar), age-dependent behavior variability and environmentally appropriate temperatures (22 and 30 °C) were also evaluated. Results indicated that oleic acid at concentrations of 0.3, 0.9 and 1.8 g/mL in beeswax significantly increased median attachment to media (median attachment of 7.50%, 4.20% and 3.71%, respectively, P0.05). Biochemical, age and environmental factors influencing cercarial host attraction and attachment behavior have been elucidated by this study. This information will inform further development of devices for environmental surveillance and potentially improve cercarial exposure prevention strategies. Copyright © 2013 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Recent Advances in Non-viral Vectors for Gene Delivery

Science.gov (United States)

Guo, Xia; Huang, Leaf

2011-01-01

CONSPECTUS Non-viral vectors, typically based on cationic lipids or polymers, are preferred due to safety concerns with viral vectors. So far, non-viral vectors can proficiently transfect cells in culture, but obtaining efficient nanomedicines is far from evident. To overcome the hurdles associated with non-viral vectors is significant for improving delivery efficiency and therapeutic effect of nucleic acid. The drawbacks include the strong interaction of cationic delivery vehicles with blood components, uptake by the reticuloendothelial system (RES), toxicity, targeting ability of the carriers to the cells of interest, and so on. PEGylation is the predominant method used to reduce the binding of plasma proteins with non-viral vectors and minimize the clearance by RES after intravenous administration. The nanoparticles that are not rapidly cleared from the circulation accumulate in the tumors due to the enhanced permeability and retention effect, and the targeting ligands attached to the distal end of the PEGylated components allow binding to the receptors on the target cell surface. Neutral or anionic liposomes have been also developed for systemic delivery of nucleic acids in experimental animal model. Designing and synthesizing novel cationic lipids and polymers, and binding nucleic acid with peptides, targeting ligands, polymers, or environmentally sensitive moieties also attract many attentions for resolving the problems encountered by non-viral vectors. The application of inorganic nanoparticles in nucleic acid delivery is an emerging field, too. Recently, different classes of non-viral vectors appear to be converging and the features of different classes of non-viral vectors could be combined in one strategy. More hurdles associated with efficient nucleic acid delivery therefore might be expected to be overcome. In this account, we will focus on these novel non-viral vectors, which are classified into multifunctional hybrid nucleic acid vectors, novel

Seven challenges for modelling indirect transmission: Vector-borne diseases, macroparasites and neglected tropical diseases

Directory of Open Access Journals (Sweden)

T. Déirdre Hollingsworth

2015-03-01

Full Text Available Many of the challenges which face modellers of directly transmitted pathogens also arise when modelling the epidemiology of pathogens with indirect transmission – whether through environmental stages, vectors, intermediate hosts or multiple hosts. In particular, understanding the roles of different hosts, how to measure contact and infection patterns, heterogeneities in contact rates, and the dynamics close to elimination are all relevant challenges, regardless of the mode of transmission. However, there remain a number of challenges that are specific and unique to modelling vector-borne diseases and macroparasites. Moreover, many of the neglected tropical diseases which are currently targeted for control and elimination are vector-borne, macroparasitic, or both, and so this article includes challenges which will assist in accelerating the control of these high-burden diseases. Here, we discuss the challenges of indirect measures of infection in humans, whether through vectors or transmission life stages and in estimating the contribution of different host groups to transmission. We also discuss the issues of “evolution-proof” interventions against vector-borne disease.

Seven challenges for modelling indirect transmission: vector-borne diseases, macroparasites and neglected tropical diseases.

Science.gov (United States)

Hollingsworth, T Déirdre; Pulliam, Juliet R C; Funk, Sebastian; Truscott, James E; Isham, Valerie; Lloyd, Alun L

2015-03-01

Many of the challenges which face modellers of directly transmitted pathogens also arise when modelling the epidemiology of pathogens with indirect transmission--whether through environmental stages, vectors, intermediate hosts or multiple hosts. In particular, understanding the roles of different hosts, how to measure contact and infection patterns, heterogeneities in contact rates, and the dynamics close to elimination are all relevant challenges, regardless of the mode of transmission. However, there remain a number of challenges that are specific and unique to modelling vector-borne diseases and macroparasites. Moreover, many of the neglected tropical diseases which are currently targeted for control and elimination are vector-borne, macroparasitic, or both, and so this article includes challenges which will assist in accelerating the control of these high-burden diseases. Here, we discuss the challenges of indirect measures of infection in humans, whether through vectors or transmission life stages and in estimating the contribution of different host groups to transmission. We also discuss the issues of "evolution-proof" interventions against vector-borne disease. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Principles of Chemical Biology: From Sexy Fatty Acids and EBV probes to Anti-Acid Antibiotic via Post-Biotics and Host-Microbe Metabolic Complementarity.

Science.gov (United States)

2017-06-22

This month: The role of fatty acids in sex determination; a probe to monitor and inhibit EBNA1 at the same time; a biological role for post-biotics; what happens when you mix microbes, hosts, and drugs; and an antibiotic that cross-protects with acid. Copyright © 2017. Published by Elsevier Ltd.

Role of Pea Enation Mosaic Virus Coat Protein in the Host Plant and Aphid Vector

Directory of Open Access Journals (Sweden)

Juliette Doumayrou

2016-11-01

Full Text Available Understanding the molecular mechanisms involved in plant virus–vector interactions is essential for the development of effective control measures for aphid-vectored epidemic plant diseases. The coat proteins (CP are the main component of the viral capsids, and they are implicated in practically every stage of the viral infection cycle. Pea enation mosaic virus 1 (PEMV1, Enamovirus, Luteoviridae and Pea enation mosaic virus 2 (PEMV2, Umbravirus, Tombusviridae are two RNA viruses in an obligate symbiosis causing the pea enation mosaic disease. Sixteen mutant viruses were generated with mutations in different domains of the CP to evaluate the role of specific amino acids in viral replication, virion assembly, long-distance movement in Pisum sativum, and aphid transmission. Twelve mutant viruses were unable to assemble but were able to replicate in inoculated leaves, move long-distance, and express the CP in newly infected leaves. Four mutant viruses produced virions, but three were not transmissible by the pea aphid, Acyrthosiphon pisum. Three-dimensional modeling of the PEMV CP, combined with biological assays for virion assembly and aphid transmission, allowed for a model of the assembly of PEMV coat protein subunits.

Role of Pea Enation Mosaic Virus Coat Protein in the Host Plant and Aphid Vector.

Science.gov (United States)

Doumayrou, Juliette; Sheber, Melissa; Bonning, Bryony C; Miller, W Allen

2016-11-18

Understanding the molecular mechanisms involved in plant virus-vector interactions is essential for the development of effective control measures for aphid-vectored epidemic plant diseases. The coat proteins (CP) are the main component of the viral capsids, and they are implicated in practically every stage of the viral infection cycle. Pea enation mosaic virus 1 (PEMV1, Enamovirus , Luteoviridae ) and Pea enation mosaic virus 2 (PEMV2, Umbravirus , Tombusviridae ) are two RNA viruses in an obligate symbiosis causing the pea enation mosaic disease. Sixteen mutant viruses were generated with mutations in different domains of the CP to evaluate the role of specific amino acids in viral replication, virion assembly, long-distance movement in Pisum sativum , and aphid transmission. Twelve mutant viruses were unable to assemble but were able to replicate in inoculated leaves, move long-distance, and express the CP in newly infected leaves. Four mutant viruses produced virions, but three were not transmissible by the pea aphid, Acyrthosiphon pisum . Three-dimensional modeling of the PEMV CP, combined with biological assays for virion assembly and aphid transmission, allowed for a model of the assembly of PEMV coat protein subunits.

Meeting the challenges of on-host and off-host water balance in blood-feeding arthropods.

Science.gov (United States)

Benoit, Joshua B; Denlinger, David L

2010-10-01

In this review, we describe water balance requirements of blood-feeding arthropods, particularly contrasting dehydration tolerance during the unfed, off-host state and the challenges of excess water that accompany receipt of the bloodmeal. Most basic water balance characteristics during the off-host stage are applicable to other terrestrial arthropods, as well. A well-coordinated suite of responses enable arthropods to conserve water resources, enhance their desiccation tolerance, and increase their water supplies by employing a diverse array of molecular, structural and behavioral responses. Water loss rates during the off-host phase are particularly useful for generating a scheme to classify vectors according to their habitat requirements for water, thus providing a convenient tool with potential predictive power for defining suitable current and future vector habitats. Blood-feeding elicits an entirely different set of challenges as the vector responds to overhydration by quickly increasing its rate of cuticular water loss and elevating the rate of diuresis to void excess water and condense the bloodmeal. Immature stages that feed on blood normally have a net increase in water content at the end of a blood-feeding cycle, but in adults the water content reverts to the pre-feeding level when the cycle is completed. Common themes are evident in diverse arthropods that feed on blood, particularly the physiological mechanisms used to respond to the sudden influx of water as well as the mechanisms used to counter water shortfalls that are encountered during the non-feeding, off-host state. Copyright 2010 Elsevier Ltd. All rights reserved.

Mosquito host choices on livestock amplifiers of Rift Valley fever virus in Kenya

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Animal hosts may vary in their attraction and acceptability as components of the host location process for assessing biting rates of vectors and risk of exposure to pathogens. However, these parameters remain poorly understood for mosquito vectors of the Rift Valley fever (RVF), an arboviral disease...

The high genetic variation of viruses of the genus Nairovirus reflects the diversity of their predominant tick hosts

International Nuclear Information System (INIS)

Honig, Jessica E.; Osborne, Jane C.; Nichol, Stuart T.

2004-01-01

The genus Nairovirus (family Bunyaviridae) contains seven serogroups consisting of 34 predominantly tick-borne viruses, including several associated with severe human and livestock diseases [e.g., Crimean Congo hemorrhagic fever (CCHF) and Nairobi sheep disease (NSD), respectively]. Before this report, no comparative genetic studies or molecular detection assays had been developed for this virus genus. To characterize at least one representative from each of the seven serogroups, reverse transcriptase-polymerase chain reaction (RT-PCR) primers targeting the L polymerase-encoding region of the RNA genome of these viruses were successfully designed based on conserved amino acid motifs present in the predicted catalytic core region. Sequence analysis showed the nairoviruses to be a highly diverse group, exhibiting up to 39.4% and 46.0% nucleotide and amino acid identity differences, respectively. Virus genetic relationships correlated well with serologic groupings and with tick host associations. Hosts of these viruses include both the hard (family Ixodidae) and soft (family Argasidae) ticks. Virus phylogenetic analysis reveals two major monophyletic groups: hard tick and soft tick-vectored viruses. In addition, viruses vectored by Ornithodoros, Carios, and Argas genera ticks also form three separate monophyletic lineages. The striking similarities between tick and nairovirus phylogenies are consistent with possible coevolution of the viruses and their tick hosts. Fossil and phylogenetic data placing the hard tick-soft tick divergence between 120 and 92 million years ago suggest an ancient origin for viruses of the genus Nairovirus

Secretion of human epidermal growth factor (EGF) in autotrophic culture by a recombinant hydrogen-utilizing bacterium, Pseudomonas pseudoflava, carrying broad-host-range EGF secretion vector pKSEGF2.

OpenAIRE

Hayase, N; Ishiyama, A; Niwano, M

1994-01-01

We constructed the broad-host-range human epidermal growth factor (EGF) secretion plasmid pKSEGF2 by inserting the Escherichia coli tac promoter, the signal sequence of Pseudomonas stutzeri amylase, and the synthesized EGF gene into the broad-host-range vector pKT230. E. coli JM109 carrying pKSEGF2 secreted EGF into the periplasm and the culture medium under the control of the tac promoter. Pseudomonas aeruginosa PAO1161 carrying pKSEGF2 and Pseudomonas putida AC10 carrying pKSEGF2 secreted E...

Haematophagous arthropod saliva and host defense system: a tale of tear and blood

Directory of Open Access Journals (Sweden)

Andrade Bruno B.

2005-01-01

Full Text Available The saliva from blood-feeding arthropod vectors is enriched with molecules that display diverse functions that mediate a successful blood meal. They function not only as weapons against host's haemostatic, inflammatory and immune responses but also as important tools to pathogen establishment. Parasites, virus and bacteria taking advantage of vectors' armament have adapted to facilitate their entry in the host. Today, many salivary molecules have been identified and characterized as new targets to the development of future vaccines. Here we focus on current information on vector's saliva and the molecules responsible to modify host's hemostasis and immune response, also regarding their role in disease transmission.

Quantitative structure–activity relationship model for amino acids as corrosion inhibitors based on the support vector machine and molecular design

International Nuclear Information System (INIS)

Zhao, Hongxia; Zhang, Xiuhui; Ji, Lin; Hu, Haixiang; Li, Qianshu

2014-01-01

Highlights: • Nonlinear quantitative structure–activity relationship (QSAR) model was built by the support vector machine. • Descriptors for QSAR model were selected by principal component analysis. • Binding energy was taken as one of the descriptors for QSAR model. • Acidic solution and protonation of the inhibitor were considered. - Abstract: The inhibition performance of nineteen amino acids was studied by theoretical methods. The affection of acidic solution and protonation of inhibitor were considered in molecular dynamics simulation and the results indicated that the protonated amino-group was not adsorbed on Fe (1 1 0) surface. Additionally, a nonlinear quantitative structure–activity relationship (QSAR) model was built by the support vector machine. The correlation coefficient was 0.97 and the root mean square error, the differences between predicted and experimental inhibition efficiencies (%), was 1.48. Furthermore, five new amino acids were theoretically designed and their inhibition efficiencies were predicted by the built QSAR model

Escaping Deleterious Immune Response in Their Hosts: Lessons from Trypanosomatids

Science.gov (United States)

Geiger, Anne; Bossard, Géraldine; Sereno, Denis; Pissarra, Joana; Lemesre, Jean-Loup; Vincendeau, Philippe; Holzmuller, Philippe

2016-01-01

The Trypanosomatidae family includes the genera Trypanosoma and Leishmania, protozoan parasites displaying complex digenetic life cycles requiring a vertebrate host and an insect vector. Trypanosoma brucei gambiense, Trypanosoma cruzi, and Leishmania spp. are important human pathogens causing human African trypanosomiasis (HAT or sleeping sickness), Chagas’ disease, and various clinical forms of Leishmaniasis, respectively. They are transmitted to humans by tsetse flies, triatomine bugs, or sandflies, and affect millions of people worldwide. In humans, extracellular African trypanosomes (T. brucei) evade the hosts’ immune defenses, allowing their transmission to the next host, via the tsetse vector. By contrast, T. cruzi and Leishmania sp. have developed a complex intracellular lifestyle, also preventing several mechanisms to circumvent the host’s immune response. This review seeks to set out the immune evasion strategies developed by the different trypanosomatids resulting from parasite–host interactions and will focus on: clinical and epidemiological importance of diseases; life cycles: parasites–hosts–vectors; innate immunity: key steps for trypanosomatids in invading hosts; deregulation of antigen-presenting cells; disruption of efficient specific immunity; and the immune responses used for parasite proliferation. PMID:27303406

ABO blood groups of residents and the ABO host choice of malaria vectors in southern Iran.

Science.gov (United States)

Anjomruz, Mehdi; Oshaghi, Mohammad A; Sedaghat, Mohammad M; Pourfatollah, Ali A; Raeisi, Ahmad; Vatandoost, Hassan; Mohtarami, Fatemeh; Yeryan, Mohammad; Bakhshi, Hassan; Nikpoor, Fatemeh

2014-01-01

Recent epidemiological evidences revealed the higher prevalence of 'O' blood group in the residents of malaria-endemic areas. Also some data indicated preference of mosquitoes to 'O' group. The aim of this study was to determine ABO group ratio in the residents as well as ABO group preference of Anopheles in two malaria endemic areas in south of Iran. Agglutination method was used for ABO typing of residents. Field blood fed Anopheles specimens were tested against vertebrate DNA using mtDNA-cytB PCR-RFLP and then the human fed specimens were tested for ABO groups using multiplex allele-specific PCR. A total of 409 human blood samples were identified, of which 150(36.7%) were 'O' group followed by 113(27.6%), 109(26.7%), and 37(9.0%) of A, B, and AB groups respectively. Analyzing of 95 blood fed mosquitoes revealed that only four Anopheles stephensi had fed human blood with A(1), B(1), and AB(2) groups. Result of this study revealed high prevalence of O group in south of Iran. To our knowledge, it is the first ABO molecular typing of blood meal in mosquitoes; however, due to low number of human blood fed specimens, ABO host choice of the mosquitoes remains unknown. This study revealed that ABO blood preference of malaria vectors and other arthropod vectors deserves future research. Copyright © 2013 Elsevier Inc. All rights reserved.

Gut-derived short-chain fatty acids are vividly assimilated into host carbohydrates and lipids

NARCIS (Netherlands)

den Besten, Gijs; Lange, Katja; Havinga, Rick; van Dijk, Theo H.; Gerding, Albert; van Eunen, Karen; Muller, Michael; Groen, Albert K.; Hooiveld, Guido J.; Bakker, Barbara M.; Reijngoud, Dirk-Jan

2013-01-01

Acetate, propionate, and butyrate are the main short-chain fatty acids (SCFAs) that arise from the fermentation of fibers by the colonic microbiota. While many studies focus on the regulatory role of SCFAs, their quantitative role as a catabolic or anabolic substrate for the host has received

Trypanosoma cruzi reservoir—triatomine vector co-occurrence networks reveal meta-community effects by synanthropic mammals on geographic dispersal

Directory of Open Access Journals (Sweden)

Carlos N. Ibarra-Cerdeña

2017-04-01

Full Text Available Contemporary patterns of land use and global climate change are modifying regional pools of parasite host species. The impact of host community changes on human disease risk, however, is difficult to assess due to a lack of information about zoonotic parasite host assemblages. We have used a recently developed method to infer parasite-host interactions for Chagas Disease (CD from vector-host co-occurrence networks. Vector-host networks were constructed to analyze topological characteristics of the network and ecological traits of species’ nodes, which could provide information regarding parasite regional dispersal in Mexico. Twenty-eight triatomine species (vectors and 396 mammal species (potential hosts were included using a data-mining approach to develop models to infer most-likely interactions. The final network contained 1,576 links which were analyzed to calculate centrality, connectivity, and modularity. The model predicted links of independently registered Trypanosoma cruzi hosts, which correlated with the degree of parasite-vector co-occurrence. Wiring patterns differed according to node location, while edge density was greater in Neotropical as compared to Nearctic regions. Vectors with greatest public health importance (i.e., Triatoma dimidiata, T. barberi, T. pallidipennis, T. longipennis, etc, did not have stronger links with particular host species, although they had a greater frequency of significant links. In contrast, hosts classified as important based on network properties were synanthropic mammals. The latter were the most common parasite hosts and are likely bridge species between these communities, thereby integrating meta-community scenarios beneficial for long-range parasite dispersal. This was particularly true for rodents, >50% of species are synanthropic and more than 20% have been identified as T. cruzi hosts. In addition to predicting potential host species using the co-occurrence networks, they reveal regions with

New Invertebrate Vectors of Okadaic Acid from the North Atlantic Waters—Portugal (Azores and Madeira) and Morocco

Science.gov (United States)

Silva, Marisa; Rodriguez, Inés; Barreiro, Aldo; Kaufmann, Manfred; Neto, Ana Isabel; Hassouani, Meryem; Sabour, Brahim; Alfonso, Amparo; Botana, Luis M.; Vasconcelos, Vitor

2015-01-01

Okadaic acid and its analogues are potent phosphatase inhibitors that cause Diarrheic Shellfish Poisoning (DSP) through the ingestion of contaminated shellfish by humans. This group of toxins is transmitted worldwide but the number of poisoning incidents has declined over the last 20 years due to legislation and monitoring programs that were implemented for bivalves. In the summer of 2012 and 2013, we collected a total of 101 samples of 22 different species that were made up of benthic and subtidal organisms such echinoderms, crustaceans, bivalves and gastropods from Madeira, São Miguel Island (Azores archipelago) and the northwestern coast of Morocco. The samples were analyzed by UPLC-MS/MS. Our main objective was to detect new vectors for these biotoxins. We can report nine new vectors for these toxins in the North Atlantic: Astropecten aranciacus, Arbacia lixula, Echinaster sepositus, Holothuria sanctori, Ophidiaster ophidianus, Onchidella celtica, Aplysia depilans, Patella spp., and Stramonita haemostoma. Differences in toxin contents among the species were found. Even though low concentrations were detected, the levels of toxins that were present, especially in edible species, indicate the importance of these types of studies. Routine monitoring should be extended to comprise a wider number of vectors other than for bivalves of okadaic acid and its analogues. PMID:26670254

New Invertebrate Vectors of Okadaic Acid from the North Atlantic Waters--Portugal (Azores and Madeira) and Morocco.

Science.gov (United States)

Silva, Marisa; Rodriguez, Inés; Barreiro, Aldo; Kaufmann, Manfred; Isabel Neto, Ana; Hassouani, Meryem; Sabour, Brahim; Alfonso, Amparo; Botana, Luis M; Vasconcelos, Vitor

2015-12-08

Okadaic acid and its analogues are potent phosphatase inhibitors that cause Diarrheic Shellfish Poisoning (DSP) through the ingestion of contaminated shellfish by humans. This group of toxins is transmitted worldwide but the number of poisoning incidents has declined over the last 20 years due to legislation and monitoring programs that were implemented for bivalves. In the summer of 2012 and 2013, we collected a total of 101 samples of 22 different species that were made up of benthic and subtidal organisms such echinoderms, crustaceans, bivalves and gastropods from Madeira, São Miguel Island (Azores archipelago) and the northwestern coast of Morocco. The samples were analyzed by UPLC-MS/MS. Our main objective was to detect new vectors for these biotoxins. We can report nine new vectors for these toxins in the North Atlantic: Astropecten aranciacus, Arbacia lixula, Echinaster sepositus, Holothuria sanctori, Ophidiaster ophidianus, Onchidella celtica, Aplysia depilans, Patella spp., and Stramonita haemostoma. Differences in toxin contents among the species were found. Even though low concentrations were detected, the levels of toxins that were present, especially in edible species, indicate the importance of these types of studies. Routine monitoring should be extended to comprise a wider number of vectors other than for bivalves of okadaic acid and its analogues.

Factors affecting the initial adhesion and retention of the plant pathogen Xylella fastidiosa in the foregut of an insect vector.

Science.gov (United States)

Killiny, Nabil; Almeida, Rodrigo P P

2014-01-01

Vector transmission of bacterial plant pathogens involves three steps: pathogen acquisition from an infected host, retention within the vector, and inoculation of cells into susceptible tissue of an uninfected plant. In this study, a combination of plant and artificial diet systems were used to determine the importance of several genes on the initial adhesion and retention of the bacterium Xylella fastidiosa to an efficient insect vector. Mutant strains included fimbrial (fimA and pilB) and afimbrial (hxfA and hxfB) adhesins and three loci involved in regulatory systems (rpfF, rpfC, and cgsA). Transmission assays with variable retention time indicated that HxfA and HxfB were primarily important for early adhesion to vectors, while FimA was necessary for both adhesion and retention. The long pilus protein PilB was not deficient in initial adhesion but may be important for retention. Genes upregulated under the control of rpfF are important for both initial adhesion and retention, as transmission rates of this mutant strain were initially low and decreased over time, while disruption of rpfC and cgsA yielded trends similar to that shown by the wild-type control. Because induction of an X. fastidiosa transmissible state requires pectin, a series of experiments were used to test the roles of a polygalacturonase (pglA) and the pectin and galacturonic acid carbohydrates on the transmission of X. fastidiosa. Results show that galacturonic acid, or PglA activity breaking pectin into its major subunit (galacturonic acid), is required for X. fastidiosa vector transmission using an artificial diet system. This study shows that early adhesion and retention of X. fastidiosa are mediated by different factors. It also illustrates that the interpretation of results of vector transmission experiments, in the context of vector-pathogen interaction studies, is highly dependent on experimental design.

Effects of simulated rain acidified with sulfuric acid on host-parasite interactions

Science.gov (United States)

D. S. Shriner

1976-01-01

Wind-blown rain, rain splash, and films of free moisture play important roles in the epidemiology of many plant diseases. The effects of simulated rain acidified with sulfuric acid were studied on several host-parasite systems. Plants were exposed, in greenhouse or field, to simulated rain of pH 3.2 ? 0.1 or pH 6.0 ? 0.2. Simulated "rain" of pH 3.2 resulted...

Vector ecology of equine piroplasmosis

Science.gov (United States)

Equine piroplasmosis (EP) is a disease of equidae including horses, donkeys, mules and zebras caused by either of two protozoan parasites, Theileria equi or Babesia caballi. These parasites are biologically transmitted between hosts via tick-vectors and although they have inherent differences, they ...

The Plasmodium bottleneck: malaria parasite losses in the mosquito vector

Science.gov (United States)

Smith, Ryan C; Vega-Rodríguez, Joel; Jacobs-Lorena, Marcelo

2014-01-01

Nearly one million people are killed every year by the malaria parasite Plasmodium. Although the disease-causing forms of the parasite exist only in the human blood, mosquitoes of the genus Anopheles are the obligate vector for transmission. Here, we review the parasite life cycle in the vector and highlight the human and mosquito contributions that limit malaria parasite development in the mosquito host. We address parasite killing in its mosquito host and bottlenecks in parasite numbers that might guide intervention strategies to prevent transmission. PMID:25185005

Adeno-Associated Virus Vectors and Stem Cells: Friends or Foes?

Science.gov (United States)

Brown, Nolan; Song, Liujiang; Kollu, Nageswara R; Hirsch, Matthew L

2017-06-01

The infusion of healthy stem cells into a patient-termed "stem-cell therapy"-has shown great promise for the treatment of genetic and non-genetic diseases, including mucopolysaccharidosis type 1, Parkinson's disease, multiple sclerosis, numerous immunodeficiency disorders, and aplastic anemia. Stem cells for cell therapy can be collected from the patient (autologous) or collected from another "healthy" individual (allogeneic). The use of allogenic stem cells is accompanied with the potentially fatal risk that the transplanted donor T cells will reject the patient's cells-a process termed "graft-versus-host disease." Therefore, the use of autologous stem cells is preferred, at least from the immunological perspective. However, an obvious drawback is that inherently as "self," they contain the disease mutation. As such, autologous cells for use in cell therapies often require genetic "correction" (i.e., gene addition or editing) prior to cell infusion and therefore the requirement for some form of nucleic acid delivery, which sets the stage for the AAV controversy discussed herein. Despite being the most clinically applied gene delivery context to date, unlike other more concerning integrating and non-integrating vectors such as retroviruses and adenovirus, those based on adeno-associated virus (AAV) have not been employed in the clinic. Furthermore, published data regarding AAV vector transduction of stem cells are inconsistent in regards to vector transduction efficiency, while the pendulum swings far in the other direction with demonstrations of AAV vector-induced toxicity in undifferentiated cells. The variation present in the literature examining the transduction efficiency of AAV vectors in stem cells may be due to numerous factors, including inconsistencies in stem-cell collection, cell culture, vector preparation, and/or transduction conditions. This review summarizes the controversy surrounding AAV vector transduction of stem cells, hopefully setting the

Vectors, hosts, and control measures for Zika virus in the Americas

Science.gov (United States)

Thompson, Sarah J.; Pearce, John; Ramey, Andy M.

2017-01-01

We examine Zika virus (ZIKV) from an ecological perspective and with a focus on the Americas. We assess (1) the role of wildlife in ZIKV disease ecology, (2) how mosquito behavior and biology influence disease dynamics, and (3) how nontarget species and ecosystems may be impacted by vector control programs. Our review suggests that free-ranging, non-human primates may be involved in ZIKV transmission in the Old World; however, other wildlife species likely play a limited role in maintaining or transmitting ZIKV. In the Americas, a zoonotic cycle has not yet been definitively established. Understanding behaviors and habitat tolerances of Aedes aegypti and Aedes albopictus, two ZIKV competent vectors in the Americas, will allow more accurate modeling of disease spread and facilitate targeted and effective control efforts. Vector control efforts may have direct and indirect impacts to wildlife, particularly invertebrate feeding species; however, strategies could be implemented to limit detrimental ecological effects.

The Plasmodium bottleneck: malaria parasite losses in the mosquito vector

Directory of Open Access Journals (Sweden)

Ryan C Smith

2014-08-01

Full Text Available Nearly one million people are killed every year by the malaria parasite Plasmodium. Although the disease-causing forms of the parasite exist only in the human blood, mosquitoes of the genus Anopheles are the obligate vector for transmission. Here, we review the parasite life cycle in the vector and highlight the human and mosquito contributions that limit malaria parasite development in the mosquito host. We address parasite killing in its mosquito host and bottlenecks in parasite numbers that might guide intervention strategies to prevent transmission.

Borrelia host adaptation Regulator (BadR) regulates rpoS to modulate host adaptation and virulence factors in Borrelia burgdorferi

OpenAIRE

Miller, Christine L.; Rajasekhar Karna, S. L.; Seshu, J.

2013-01-01

The RpoS transcription factor of Borrelia burgdorferi is a “gatekeeper” because it activates genes required for spirochetes to transition from tick to vertebrate hosts. However, it remains unknown how RpoS becomes repressed to allow the spirochetes to transition back from the vertebrate host to the tick vector. Here we show that a putative carbohydrate-responsive regulatory protein, designated BadR (Borrelia host adaptation Regulator), is a transcriptional repressor of rpoS. BadR levels are e...

Acetic Acid Bacteria as Symbionts of Insects

KAUST Repository

Crotti, Elena; Chouaia, Bessem; Alma, Alberto; Favia, Guido; Bandi, Claudio; Bourtzis, Kostas; Daffonchio, Daniele

2016-01-01

Acetic acid bacteria (AAB) are being increasingly described as associating with different insect species that rely on sugar-based diets. AAB have been found in several insect orders, among them Diptera, Hemiptera, and Hymenoptera, including several vectors of plant, animal, and human diseases. AAB have been shown to associate with the epithelia of different organs of the host, they are able to move within the insect’s body and to be transmitted horizontally and vertically. Here, we review the ecology of AAB and examine their relationships with different insect models including mosquitoes, leafhoppers, and honey bees. We also discuss the potential use of AAB in symbiont-based control strategies, such as “Trojan-horse” agents, to block the transmission of vector-borne diseases.

Acetic Acid Bacteria as Symbionts of Insects

KAUST Repository

Crotti, Elena

2016-06-14

Acetic acid bacteria (AAB) are being increasingly described as associating with different insect species that rely on sugar-based diets. AAB have been found in several insect orders, among them Diptera, Hemiptera, and Hymenoptera, including several vectors of plant, animal, and human diseases. AAB have been shown to associate with the epithelia of different organs of the host, they are able to move within the insect’s body and to be transmitted horizontally and vertically. Here, we review the ecology of AAB and examine their relationships with different insect models including mosquitoes, leafhoppers, and honey bees. We also discuss the potential use of AAB in symbiont-based control strategies, such as “Trojan-horse” agents, to block the transmission of vector-borne diseases.

Bartonella in Rodents and Ectoparasites in the Canary Islands, Spain: New Insights into Host-Vector-Pathogen Relationships.

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Abreu-Yanes, Estefania; Martin-Alonso, Aaron; Martin-Carrillo, Natalia; Livia, Katherine Garcia; Marrero-Gagliardi, Alessandro; Valladares, Basilio; Feliu, Carlos; Foronda, Pilar

2018-01-01

Bartonella genus is comprised of several species of zoonotic relevance and rodents are reservoirs for some of these Bartonella species. As there were no data about the range of Bartonella species circulating among rodents in the Canary Islands, our main aim was to overcome this lack of knowledge by targeting both the citrate synthase (gltA) and the RNA polymerase beta subunit (rpoB) genes. A total of 181 small mammals and 154 ectoparasites were obtained in three of the Canary Islands, namely Tenerife, La Palma, and Lanzarote. The overall prevalence of Bartonella DNA in rodents was 18.8%, whereas the prevalence in ectoparasites was 13.6%. Bartonella sequences closely related to the zoonotic species Bartonella elizabethae, Bartonella tribocorum, and Bartonella rochalimae were identified in rodents, whereas two different gltA haplotypes similar to B. elizabethae were also detected in fleas. Furthermore, Bartonella queenslandensis DNA was also identified in rodents. A strong host specificity was observed, since B. elizabethae DNA was only found in Mus musculus domesticus, whereas gltA and rpoB sequences closely related to the rest of Bartonella species were only identified in Rattus rattus, which is probably due to the host specificity of the arthropod species that act as vectors in these islands. Our results indicate that humans may contract Bartonella infection by contact with rodents in the Canary Islands.

Molecular Characterization of Heterologous HIV-1gp120 Gene Expression Disruption in Mycobacterium bovis BCG Host Strain: A Critical Issue for Engineering Mycobacterial Based-Vaccine Vectors

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Joseph, Joan; Fernández-Lloris, Raquel; Pezzat, Elías; Saubi, Narcís; Cardona, Pere-Joan; Mothe, Beatriz; Gatell, Josep Maria

2010-01-01

Mycobacterium bovis Bacillus Calmette-Guérin (BCG) as a live vector of recombinant bacterial vaccine is a promising system to be used. In this study, we evaluate the disrupted expression of heterologous HIV-1gp120 gene in BCG Pasteur host strain using replicative vectors pMV261 and pJH222. pJH222 carries a lysine complementing gene in BCG lysine auxotrophs. The HIV-1 gp120 gene expression was regulated by BCG hsp60 promoter (in plasmid pMV261) and Mycobacteria spp. α-antigen promoter (in plasmid pJH222). Among 14 rBCG:HIV-1gp120 (pMV261) colonies screened, 12 showed a partial deletion and two showed a complete deletion. However, deletion was not observed in all 10 rBCG:HIV-1gp120 (pJH222) colonies screened. In this study, we demonstrated that E. coli/Mycobacterial expression vectors bearing a weak promoter and lysine complementing gene in a recombinant lysine auxotroph of BCG could prevent genetic rearrangements and disruption of HIV 1gp120 gene expression, a key issue for engineering Mycobacterial based vaccine vectors. PMID:20617151

Molecular Characterization of Heterologous HIV-1gp120 Gene Expression Disruption in Mycobacterium bovis BCG Host Strain: A Critical Issue for Engineering Mycobacterial Based-Vaccine Vectors

Directory of Open Access Journals (Sweden)

Joan Joseph

2010-01-01

Full Text Available Mycobacterium bovis Bacillus Calmette-Guérin (BCG as a live vector of recombinant bacterial vaccine is a promising system to be used. In this study, we evaluate the disrupted expression of heterologous HIV-1gp120 gene in BCG Pasteur host strain using replicative vectors pMV261 and pJH222. pJH222 carries a lysine complementing gene in BCG lysine auxotrophs. The HIV-1 gp120 gene expression was regulated by BCG hsp60 promoter (in plasmid pMV261 and Mycobacteria spp. α-antigen promoter (in plasmid pJH222. Among 14 rBCG:HIV-1gp120 (pMV261 colonies screened, 12 showed a partial deletion and two showed a complete deletion. However, deletion was not observed in all 10 rBCG:HIV-1gp120 (pJH222 colonies screened. In this study, we demonstrated that E. coli/Mycobacterial expression vectors bearing a weak promoter and lysine complementing gene in a recombinant lysine auxotroph of BCG could prevent genetic rearrangements and disruption of HIV 1gp120 gene expression, a key issue for engineering Mycobacterial based vaccine vectors.

Plant Hormone Salicylic Acid Produced by a Malaria Parasite Controls Host Immunity and Cerebral Malaria Outcome.

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Ryuma Matsubara

Full Text Available The apicomplexan parasite Toxoplasma gondii produces the plant hormone abscisic acid, but it is unclear if phytohormones are produced by the malaria parasite Plasmodium spp., the most important parasite of this phylum. Here, we report detection of salicylic acid, an immune-related phytohormone of land plants, in P. berghei ANKA and T. gondii cell lysates. However, addition of salicylic acid to P. falciparum and T. gondii culture had no effect. We transfected P. falciparum 3D7 with the nahG gene, which encodes a salicylic acid-degrading enzyme isolated from plant-infecting Pseudomonas sp., and established a salicylic acid-deficient mutant. The mutant had a significantly decreased concentration of parasite-synthesized prostaglandin E2, which potentially modulates host immunity as an adaptive evolution of Plasmodium spp. To investigate the function of salicylic acid and prostaglandin E2 on host immunity, we established P. berghei ANKA mutants expressing nahG. C57BL/6 mice infected with nahG transfectants developed enhanced cerebral malaria, as assessed by Evans blue leakage and brain histological observation. The nahG-transfectant also significantly increased the mortality rate of mice. Prostaglandin E2 reduced the brain symptoms by induction of T helper-2 cytokines. As expected, T helper-1 cytokines including interferon-γ and interleukin-2 were significantly elevated by infection with the nahG transfectant. Thus, salicylic acid of Plasmodium spp. may be a new pathogenic factor of this threatening parasite and may modulate immune function via parasite-produced prostaglandin E2.

The relationship between host lifespan and pathogen reservoir potential: an analysis in the system Arabidopsis thaliana--cucumber mosaic virus.

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Jean Michel Hily

2014-11-01

Full Text Available Identification of the determinants of pathogen reservoir potential is central to understand disease emergence. It has been proposed that host lifespan is one such determinant: short-lived hosts will invest less in costly defenses against pathogens, so that they will be more susceptible to infection, more competent as sources of infection and/or will sustain larger vector populations, thus being effective reservoirs for the infection of long-lived hosts. This hypothesis is sustained by analyses of different hosts of multihost pathogens, but not of different genotypes of the same host species. Here we examined this hypothesis by comparing two genotypes of the plant Arabidopsis thaliana that differ largely both in life-span and in tolerance to its natural pathogen Cucumber mosaic virus (CMV. Experiments with the aphid vector Myzus persicae showed that both genotypes were similarly competent as sources for virus transmission, but the short-lived genotype was more susceptible to infection and was able to sustain larger vector populations. To explore how differences in defense against CMV and its vector relate to reservoir potential, we developed a model that was run for a set of experimentally-determined parameters, and for a realistic range of host plant and vector population densities. Model simulations showed that the less efficient defenses of the short-lived genotype resulted in higher reservoir potential, which in heterogeneous host populations may be balanced by the longer infectious period of the long-lived genotype. This balance was modulated by the demography of both host and vector populations, and by the genetic composition of the host population. Thus, within-species genetic diversity for lifespan and defenses against pathogens will result in polymorphisms for pathogen reservoir potential, which will condition within-population infection dynamics. These results are relevant for a better understanding of host-pathogen co-evolution, and of

Vector Contact Rates on Eastern Bluebird Nestlings Do Not Indicate West Nile Virus Transmission in Henrico County, Virginia, USA

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Kevin A. Caillouët

2013-11-01

Full Text Available Sensitive indicators of spatial and temporal variation in vector-host contact rates are critical to understanding the transmission and eventual prevention of arboviruses such as West Nile virus (WNV. Monitoring vector contact rates on particularly susceptible and perhaps more exposed avian nestlings may provide an advanced indication of local WNV amplification. To test this hypothesis we monitored WNV infection and vector contact rates among nestlings occupying nest boxes (primarily Eastern bluebirds; Sialia sialis, Turdidae across Henrico County, Virginia, USA, from May to August 2012. Observed host-seeking rates were temporally variable and associated with absolute vector and host abundances. Despite substantial effort to monitor WNV among nestlings and mosquitoes, we did not detect the presence of WNV in these populations. Generally low vector-nestling host contact rates combined with the negative WNV infection data suggest that monitoring transmission parameters among nestling Eastern bluebirds in Henrico County, Virginia, USA may not be a sensitive indicator of WNV activity.

Vector-transmitted disease vaccines: targeting salivary proteins in transmission (SPIT).

Science.gov (United States)

McDowell, Mary Ann

2015-08-01

More than half the population of the world is at risk for morbidity and mortality from vector-transmitted diseases, and emerging vector-transmitted infections are threatening new populations. Rising insecticide resistance and lack of efficacious vaccines highlight the need for novel control measures. One such approach is targeting the vector-host interface by incorporating vector salivary proteins in anti-pathogen vaccines. Debate remains about whether vector saliva exposure exacerbates or protects against more severe clinical manifestations, induces immunity through natural exposure or extends to all vector species and associated pathogens. Nevertheless, exploiting this unique biology holds promise as a viable strategy for the development of vaccines against vector-transmitted diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simulation of climate-tick-host-landscape interactions: Effects of shifts in the seasonality of host population fluctuations on tick densities.

Science.gov (United States)

Wang, Hsiao-Hsuan; Grant, W E; Teel, P D; Hamer, S A

2015-12-01

Tick vector systems are comprised of complex climate-tick-host-landscape interactions that are difficult to identify and estimate from empirical observations alone. We developed a spatially-explicit, individual-based model, parameterized to represent ecological conditions typical of the south-central United States, to examine effects of shifts in the seasonal occurrence of fluctuations of host densities on tick densities. Simulated shifts in the seasonal occurrence of periods of high and low host densities affected both the magnitude of unfed tick densities and the seasonality of tick development. When shifting the seasonal densities of all size classes of hosts (small, medium, and large) synchronously, densities of nymphs were affected more by smaller shifts away from the baseline host seasonality than were densities of larval and adult life stages. When shifting the seasonal densities of only a single size-class of hosts while holding other size classes at their baseline levels, densities of larval, nymph, and adult life stages responded differently. Shifting seasonal densities of any single host-class earlier resulted in a greater increase in adult tick density than when seasonal densities of all host classes were shifted earlier simultaneously. The mean densities of tick life stages associated with shifts in host densities resulted from system-level interactions of host availability with tick phenology. For example, shifting the seasonality of all hosts ten weeks earlier resulted in an approximately 30% increase in the relative degree of temporal co-occurrence of actively host-seeking ticks and hosts compared to baseline, whereas shifting the seasonality of all hosts ten weeks later resulted in an approximately 70% decrease compared to baseline. Differences among scenarios in the overall presence of active host-seeking ticks in the system were due primarily to the degree of co-occurrence of periods of high densities of unfed ticks and periods of high densities

Interactions between parasites and insects vectors

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Hilary Hurd

1994-01-01

Full Text Available This review stresses the importance of studies that will provide a basic understanding of the pathology of parasite-infected vector insects. This knowledge should be a vital component of the very focussed initiatives currently being funded in the areas of vector control. Vector fecundity reduction is discussed as an example of such pathology. Underlying mechanisms are being investigated in a model system, Hymenolepis diminuta-infected Tenebrio molitor and in Onchocerca-infected blackflies and Plasmodium-infected Anopheles stephensi. In all cases, host vitellogenesis is disrupted by the parasite and, in the tapeworm/beetle model, interaction between the parasite and the endocrine control of the insect's reproductive physiology has been demonstrated.

Distribution of Bartonella henselae Variants in Patients, Reservoir Hosts and Vectors in Spain

Science.gov (United States)

Gil, Horacio; Escudero, Raquel; Pons, Inmaculada; Rodríguez-Vargas, Manuela; García-Esteban, Coral; Rodríguez-Moreno, Isabel; García-Amil, Cristina; Lobo, Bruno; Valcárcel, Félix; Pérez, Azucena; Jiménez, Santos; Jado, Isabel; Juste, Ramón; Segura, Ferrán; Anda, Pedro

2013-01-01

We have studied the diversity of B. henselae circulating in patients, reservoir hosts and vectors in Spain. In total, we have fully characterized 53 clinical samples from 46 patients, as well as 78 B. henselae isolates obtained from 35 cats from La Rioja and Catalonia (northeastern Spain), four positive cat blood samples from which no isolates were obtained, and three positive fleas by Multiple Locus Sequence Typing and Multiple Locus Variable Number Tandem Repeats Analysis. This study represents the largest series of human cases characterized with these methods, with 10 different sequence types and 41 MLVA profiles. Two of the sequence types and 35 of the profiles were not described previously. Most of the B. henselae variants belonged to ST5. Also, we have identified a common profile (72) which is well distributed in Spain and was found to persist over time. Indeed, this profile seems to be the origin from which most of the variants identified in this study have been generated. In addition, ST5, ST6 and ST9 were found associated with felines, whereas ST1, ST5 and ST8 were the most frequent sequence types found infecting humans. Interestingly, some of the feline associated variants never found on patients were located in a separate clade, which could represent a group of strains less pathogenic for humans. PMID:23874563

Characterization of a Brome mosaic virus strain and its use as a vector for gene silencing in monocotyledonous hosts.

Science.gov (United States)

Ding, Xin Shun; Schneider, William L; Chaluvadi, Srinivasa Rao; Mian, M A Rouf; Nelson, Richard S

2006-11-01

Virus-induced gene silencing (VIGS) is used to analyze gene function in dicotyledonous plants but less so in monocotyledonous plants (particularly rice and corn), partially due to the limited number of virus expression vectors available. Here, we report the cloning and modification for VIGS of a virus from Festuca arundinacea Schreb. (tall fescue) that caused systemic mosaic symptoms on barley, rice, and a specific cultivar of maize (Va35) under greenhouse conditions. Through sequencing, the virus was determined to be a strain of Brome mosaic virus (BMV). The virus was named F-BMV (F for Festuca), and genetic determinants that controlled the systemic infection of rice were mapped to RNAs 1 and 2 of the tripartite genome. cDNA from RNA 3 of the Russian strain of BMV (R-BMV) was modified to accept inserts from foreign genes. Coinoculation of RNAs 1 and 2 from F-BMV and RNA 3 from R-BMV expressing a portion of a plant gene to leaves of barley, rice, and maize plants resulted in visual silencing-like phenotypes. The visual phenotypes were correlated with decreased target host transcript levels in the corresponding leaves. The VIGS visual phenotype varied from maintained during silencing of actin 1 transcript expression to transient with incomplete penetration through affected tissue during silencing of phytoene desaturase expression. F-BMV RNA 3 was modified to allow greater accumulation of virus while minimizing virus pathogenicity. The modified vector C-BMV(A/G) (C for chimeric) was shown to be useful for VIGS. These BMV vectors will be useful for analysis of gene function in rice and maize for which no VIGS system is reported.

Mutational library analysis of selected amino acids in the receptor binding domain of envelope of Akv murine leukemia virus by conditionally replication competent bicistronic vectors

DEFF Research Database (Denmark)

Bahrami, Shervin; Jespersen, Thomas; Pedersen, Finn Skou

2003-01-01

The envelope protein of retroviruses is responsible for viral entry into host cells. Here, we describe a mutational library approach to dissect functional domains of the envelope protein involving a retroviral vector, which expresses both the envelope protein of Akv murine leukemia virus (MLV) an...

Vector species richness increases haemorrhagic disease prevalence through functional diversity modulating the duration of seasonal transmission.

Science.gov (United States)

Park, Andrew W; Cleveland, Christopher A; Dallas, Tad A; Corn, Joseph L

2016-06-01

Although many parasites are transmitted between hosts by a suite of arthropod vectors, the impact of vector biodiversity on parasite transmission is poorly understood. Positive relationships between host infection prevalence and vector species richness (SR) may operate through multiple mechanisms, including (i) increased vector abundance, (ii) a sampling effect in which species of high vectorial capacity are more likely to occur in species-rich communities, and (iii) functional diversity whereby communities comprised species with distinct phenologies may extend the duration of seasonal transmission. Teasing such mechanisms apart is impeded by a lack of appropriate data, yet could highlight a neglected role for functional diversity in parasite transmission. We used statistical modelling of extensive host, vector and microparasite data to test the hypothesis that functional diversity leading to longer seasonal transmission explained variable levels of disease in a wildlife population. We additionally developed a simple transmission model to guide our expectation of how an increased transmission season translates to infection prevalence. Our study demonstrates that vector SR is associated with increased levels of disease reporting, but not via increases in vector abundance or via a sampling effect. Rather, the relationship operates by extending the length of seasonal transmission, in line with theoretical predictions.

Crimean-Congo Hemorrhagic Fever: Tick-Host-Virus Interactions

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Anna Papa

2017-05-01

Full Text Available Crimean-Congo hemorrhagic fever virus (CCHFV is transmitted to humans by bite of infected ticks or by direct contact with blood or tissues of viremic patients or animals. It causes to humans a severe disease with fatality up to 30%. The current knowledge about the vector-host-CCHFV interactions is very limited due to the high-level containment required for CCHFV studies. Among ticks, Hyalomma spp. are considered the most competent virus vectors. CCHFV evades the tick immune response, and following its replication in the lining of the tick's midgut, it is disseminated by the hemolymph in the salivary glands and reproductive organs. The introduction of salivary gland secretions into the host cells is the major route via which CCHFV enters the host. Following an initial amplification at the site of inoculation, the virus is spread to the target organs. Apoptosis is induced via both intrinsic and extrinsic pathways. Genetic factors and immune status of the host may affect the release of cytokines which play a major role in disease progression and outcome. It is expected that the use of new technology of metabolomics, transcriptomics and proteomics will lead to improved understanding of CCHFV-host interactions and identify potential targets for blocking the CCHFV transmission.

wFlu: characterization and evaluation of a native Wolbachia from the mosquito Aedes fluviatilis as a potential vector control agent.

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Luke Anthony Baton

Full Text Available There is currently considerable interest and practical progress in using the endosymbiotic bacteria Wolbachia as a vector control agent for human vector-borne diseases. Such vector control strategies may require the introduction of multiple, different Wolbachia strains into target vector populations, necessitating the identification and characterization of appropriate endosymbiont variants. Here, we report preliminary characterization of wFlu, a native Wolbachia from the neotropical mosquito Aedes fluviatilis, and evaluate its potential as a vector control agent by confirming its ability to cause cytoplasmic incompatibility, and measuring its effect on three parameters determining host fitness (survival, fecundity and fertility, as well as vector competence (susceptibility for pathogen infection. Using an aposymbiotic strain of Ae. fluviatilis cured of its native Wolbachia by antibiotic treatment, we show that in its natural host wFlu causes incomplete, but high levels of, unidirectional cytoplasmic incompatibility, has high rates of maternal transmission, and no detectable fitness costs, indicating a high capacity to rapidly spread through host populations. However, wFlu does not inhibit, and even enhances, oocyst infection with the avian malaria parasite Plasmodium gallinaceum. The stage- and sex-specific density of wFlu was relatively low, and with limited tissue distribution, consistent with the lack of virulence and pathogen interference/symbiont-mediated protection observed. Unexpectedly, the density of wFlu was also shown to be specifically-reduced in the ovaries after bloodfeeding Ae. fluviatilis. Overall, our observations indicate that the Wolbachia strain wFlu has the potential to be used as a vector control agent, and suggests that appreciable mutualistic coevolution has occurred between this endosymbiont and its natural host. Future work will be needed to determine whether wFlu has virulent host effects and/or exhibits pathogen

Nucleic acid probes as a diagnostic method for tick-borne hemoparasites of veterinary importance.

Science.gov (United States)

Figueroa, J V; Buening, G M

1995-03-01

An increased number of articles on the use of nucleic acid-based hybridization techniques for diagnostic purposes have been recently published. This article reviews nucleic acid-based hybridization as an assay to detect hemoparasite infections of economic relevance in veterinary medicine. By using recombinant DNA techniques, selected clones containing inserts of Anaplasma, Babesia, Cowdria or Theileria genomic DNA sequences have been obtained, and they are now available to be utilized as specific, highly sensitive DNA or RNA probes to detect the presence of the hemoparasite DNA in an infected animal. Either in an isotopic or non-isotopic detection system, probes have allowed scientists to test for--originally in samples collected from experimentally infected animals and later in samples collected in the field--the presence of hemoparasites during the prepatent, patent, convalescent, and chronic periods of the infection in the host. Nucleic acid probes have given researchers the opportunity to carry out genomic analysis of parasite DNA to differentiate hemoparasite species and to identify genetically distinct populations among and within isolates, strains and clonal populations. Prevalence of parasite infection in the tick vector can now be accomplished more specifically with the nucleic acid probes. Lately, with the advent of the polymerase chain reaction technique, small numbers of hemoparasites can be positively identified in the vertebrate host and tick vector. These techniques can be used to assess the veterinary epidemiological situation in a particular geographical region for the planning of control measures.

Contribution of rpfB to cell-to-cell signal synthesis, virulence, and vector transmission of Xylella fastidiosa.

Science.gov (United States)

Almeida, Rodrigo P P; Killiny, Nabil; Newman, Karyn L; Chatterjee, Subhadeep; Ionescu, Michael; Lindow, Steven E

2012-04-01

In Xylella fastidiosa the fatty acid signal molecule diffusible signaling factor (DSF) is produced and sensed by components of the regulation of pathogenicity factors (rpf) cluster; lack of DSF production in RpfF mutants results in a non-vector-transmissible phenotype yet cells are hypervirulent to grape. rpfB has not been characterized in Xylella fastidiosa, although its homolog has been suggested to be required for DSF synthesis in Xanthomonas campestris pv. campestris. We show that RpfB is involved in DSF processing in both Xylella fastidiosa and Xanthomonas campestris, affecting the profile of DSF-like fatty acids observed in thin-layer chromatography. Although three fatty acids whose production is dependent on RpfF were detected in Xylella fastidiosa and Xanthomonas campestris wild-type strains, their respective rpfB mutants accumulated primarily one chemical species. Although no quantifiable effect of rpfB on plant colonization by Xylella fastidiosa was found, insect colonization and transmission was reduced. Thus, RpfB apparently is involved in DSF processing, and like Xanthomonas campestris, Xylella fastidiosa also produces multiple DSF molecules. It is possible that Xylella fastidiosa coordinates host vector and plant colonization by varying the proportions of different forms of DSF signals via RpfB.

Comparative genetic diversity of Lyme disease bacteria in Northern Californian ticks and their vertebrate hosts.

Science.gov (United States)

Swei, Andrea; Bowie, Verna C; Bowie, Rauri C K

2015-04-01

Vector-borne pathogens are transmitted between vertebrate hosts and arthropod vectors, two immensely different environments for the pathogen. There is further differentiation among vertebrate hosts that often have complex, species-specific immunological responses to the pathogen. All this presents a heterogeneous environmental and immunological landscape with possible consequences on the population genetic structure of the pathogen. We evaluated the differential genetic diversity of the Lyme disease pathogen, Borrelia burgdorferi, in its vector, the western black-legged tick (Ixodes pacificus), and in its mammal host community using the 5S-23S rRNA intergenic spacer region. We found differences in haplotype distribution of B. burgdorferi in tick populations from two counties in California as well as between a sympatric tick and vertebrate host community. In addition, we found that three closely related haplotypes consistently occurred in high frequency in all sample types. Lastly, our study found lower species diversity of the B. burgdorferi species complex, known as B. burgdorferi sensu lato, in small mammal hosts versus the tick populations in a sympatric study area. Copyright © 2015 Elsevier GmbH. All rights reserved.

Vertebrate host specificity and experimental vectors of Plasmodium (Novyella) kempi sp. n. from the eastern wild turkey in Iowa.

Science.gov (United States)

Christensen, B M; Barnes, H J; Rowley, W A

1983-07-01

Vertebrate host specificity, experimental laboratory vectors, and a description of Plasmodium (Novyella) kempi sp. n. from eastern wild turkeys (Meleagris gallopavo silvestris Vieillot) in Iowa are presented. Plasmodium kempi is infective for domestic turkeys, bobwhites (Colinus virginianus), chukars (Alectoris graeca), guinea fowl (Numida meleagris), peacocks (Pavo cristatus), and canaries (Serinus canaria), produces a transient infection in mallards (Anas platyrhynchos) and domestic geese (Anser anser), but will not infect ring-necked pheasants (Phasianus colchicus), pigeons (Columba livia), Japanese quail (Coturnix coturnix), leghorn white chickens (Gallus gallus), or starlings (Sturnus vulgaris). Oocysts and (or) sporozoites were recovered from 68% (84/124) and 98% (60/61) of the Culex pipiens pipiens and C. tarsalis examined, respectively. Oocysts developed faster and sporozoites invaded the salivary glands sooner in C. tarsalis (6 days) than in C. p. pipiens (7 days). Culex tarsalis transmitted P. kempi more effectively than C. p. pipiens, although both species were capable of transmitting the parasite by natural feeding. Oocysts developed and sporozoites also were produced in C. restuans, but its ability to transmit the parasite was not determined. Aedes aegypti (Rockefeller strain) and A. triseriatus were refractive to P. kempi. Plasmodium kempi produces trophozoites with large refractile globules and fine cytoplasmic extensions, mature schizonts in the form of a condensed fan containing four to eight nuclei (usually 5), and elongate gametocytes with irregular borders. All stages are confined almost exclusively to mature erythrocytes, with no effect on host cell size or position of host cell nucleus. Plasmodium kempi is most similar morphologically to P. (Novyella) hexamerium and P. (Novyella) vaughani. It differs from P. hexamerium in having large refractile globules in trophozoites and immature schizonts, an inability to infect starlings, an absence of

Vectors, viscin, and Viscaceae: mistletoes as parasites, mutualists, and resources.

Science.gov (United States)

Juliann E. Aukema

2003-01-01

Mistletoes are aerial, hemiparasitic plants found on trees throughout the world. They have unique ecological arrangements with the host plants they parasitize and the birds that disperse their seeds. Similar in many respects to vector-borne macroparasites, mistletoes are often detrimental to their hosts, and can even kill them. Coevolution has led to resistance...

A putative ATP/GTP binding protein affects Leishmania mexicana growth in insect vectors and vertebrate hosts

Science.gov (United States)

Hlaváčová, Jana; Zimmer, Sara L.; Butenko, Anzhelika; Podešvová, Lucie; Leštinová, Tereza; Lukeš, Julius; Kostygov, Alexei; Votýpka, Jan; Volf, Petr

2017-01-01

Background Leishmania virulence factors responsible for the complicated epidemiology of the various leishmaniases remain mainly unidentified. This study is a characterization of a gene previously identified as upregulated in two of three overlapping datasets containing putative factors important for Leishmania’s ability to establish mammalian intracellular infection and to colonize the gut of an insect vector. Methodology/Principal findings The investigated gene encodes ATP/GTP binding motif-containing protein related to Leishmania development 1 (ALD1), a cytosolic protein that contains a cryptic ATP/GTP binding P-loop. We compared differentiation, growth rates, and infective abilities of wild-type and ALD1 null mutant cell lines of L. mexicana. Loss of ALD1 results in retarded growth kinetics but not defects in differentiation in axenic culture. Similarly, when mice and the sand fly vector were infected with the ALD1 null mutant, the primary difference in infection and colonization phenotype relative to wild type was an inability to achieve maximal host pathogenicity. While ability of the ALD1 null mutant cells to infect macrophages in vitro was not affected, replication within macrophages was clearly curtailed. Conclusions/Significance L. mexicana ALD1, encoding a protein with no assigned functional domains or motifs, was identified utilizing multiple comparative analyses with the related and often experimentally overlooked monoxenous flagellates. We found that it plays a role in Leishmania infection and colonization in vitro and in vivo. Results suggest that ALD1 functions in L. mexicana’s general metabolic network, rather than function in specific aspect of virulence as anticipated from the compared datasets. This result validates our comparative genomics approach for finding relevant factors, yet highlights the importance of quality laboratory-based analysis of genes tagged by these methods. PMID:28742133

Host cells and methods for producing diacid compounds

Energy Technology Data Exchange (ETDEWEB)

Steen, Eric J.; Fortman, Jeffrey L.; Dietrich, Jeffrey A.; Keasling, Jay D.

2018-04-24

The present invention provides for a method of producing one or more fatty acid derived dicarboxylic acids in a genetically modified host cell which does not naturally produce the one or more derived fatty acid derived dicarboxylic acids. The invention provides for the biosynthesis of dicarboxylic acid ranging in length from C3 to C26. The host cell can be further modified to increase fatty acid production or export of the desired fatty acid derived compound, and/or decrease fatty acid storage or metabolism.

Global climate change and vector-borne diseases

Science.gov (United States)

Ginsberg, H.S.

2002-01-01

Global warming will have different effects on different diseases because of the complex and idiosynchratic interactions between vectors, hosts, and pathogens that influence transmission dynamics of each pathogen. Human activities, including urbanization, rapid global travel, and vector management, have profound effects on disease transmission that can operate on more rapid time scales than does global climate change. The general concern about global warming encouraging the spread of tropical diseases is legitimate, but the effects vary among diseases, and the ecological implications are difficult to predict.

[Feeding pattern of Rift Valley Fever virus vectors in Senegal. Implications in the disease epidemiology].

Science.gov (United States)

Ba, Y; Diallo, D; Dia, I; Diallo, M

2006-10-01

During the rainy season 2003, an entomological survey was undertaken in the Sahelian bioclimatic zone of the Ferlo area in northern Senegal, in order to evaluate the degree of interaction between Rift valley fever (RVF) virus vectors and domestic animals and to determine the role of natural vertebrate hosts in the transmission and maintenance cycle. The study of vector-host contact was carried out under bed net traps using man, cow, sheep, chicken as bait whereas the RVFV vectors-vertebrate host interactions were studied through the analysis by an ELISA technique of the origin of the blood meals from naturally engorged females collected by aspiration. Blood meals sources were determined using a set of eight antibodies. Overall, the different known RVFV vectors (Culex poicilipes, Aedes vexans and Aedes ochraceus) were opportunistic although the bovine-baited net was, as far the more effective trap with 53.6% of collected mosquitoes. It was followed by the sheep-baited net (16.7%), man-baited net (12.6%) and chicken-baited net (11.6%). The more effectiveness of the bovine-baited net confirms the degree of implication of this host in RVF epidemiology. The study of vector-hosts interactions in nature showed that among the 1,112 mosquito blood meals tested, 701 were identified of which 693 were from Aedes vexans. The percentage of non-reacting blood meal was 36.7% whereas 16.9 % of the blood meals were taken at least on two vertebrate hosts. Overall, 53.2% of the blood meals from Ae. vexans were taken on equine, 18.6% on bovines, 7.1% on sheep and 0.6% on human. No blood meal was taken on rodent. The greatest diversity was observed in August. These host feedings patterns show that although equine is known to play a minor role in RVF epidemiology a thorough attention should be made to this host with regard to the percentage of blood meals taken in this host. The low percentage of blood meals taken on human could probably explain the low human infection rate observed up

Modelling spread of Bluetongue and other vector borne diseases in Denmark and evaluation of intervention strategies

DEFF Research Database (Denmark)

Græsbøll, Kaare

that describes spread of disease using vectors or hosts as agents of the spread. The model is run with bluetongue as the primary case study, and it is demonstrated how an epidemic outbreak of bluetongue 8 in Denmark is sensitive to the use of pasture, climate, vaccination, vector abundance, and flying parameters......The main outcome of this PhD project is a generic model for non-contagious infectious vector-borne disease spread by one vector species between up to two species of hosts distributed on farms and pasture. The model features a within-herd model of disease, combined with a triple movement kernel....... In constructing a more process oriented agent-based approach to spread modeling new parameters describing vector behavior were introduced. When these vector flying parameters have been quantified by experiments, this model can be implemented on areas naïve to the modeled disease with a high predictive power...

Viral Hybrid Vectors for Somatic Integration - Are They the Better Solution?

Directory of Open Access Journals (Sweden)

Anja Ehrhardt

2009-12-01

Full Text Available The turbulent history of clinical trials in viral gene therapy has taught us important lessons about vector design and safety issues. Much effort was spent on analyzing genotoxicity after somatic integration of therapeutic DNA into the host genome. Based on these findings major improvements in vector design including the development of viral hybrid vectors for somatic integration have been achieved. This review provides a state-of-the-art overview of available hybrid vectors utilizing viruses for high transduction efficiencies in concert with various integration machineries for random and targeted integration patterns. It discusses advantages but also limitations of each vector system.

The Insect Microbiome Modulates Vector Competence for Arboviruses

Directory of Open Access Journals (Sweden)

Natapong Jupatanakul

2014-11-01

Full Text Available Diseases caused by arthropod-borne viruses (arboviruses, such as Dengue, West Nile, and Chikungunya, constitute a major global health burden and are increasing in incidence and geographic range. The natural microbiota of insect vectors influences various aspects of host biology, such as nutrition, reproduction, metabolism, and immunity, and recent studies have highlighted the ability of insect-associated bacteria to reduce vector competence for arboviruses and other pathogens. This reduction can occur through mechanisms, such as immune response activation, resource competition, or the production of anti-viral molecules. Studying the interactions between insect vectors and their microbiota is an important step toward developing alternative strategies for arbovirus transmission control.

Integrating Transgenic Vector Manipulation with Clinical Interventions to Manage Vector-Borne Diseases.

Directory of Open Access Journals (Sweden)

Kenichi W Okamoto

2016-03-01

Full Text Available Many vector-borne diseases lack effective vaccines and medications, and the limitations of traditional vector control have inspired novel approaches based on using genetic engineering to manipulate vector populations and thereby reduce transmission. Yet both the short- and long-term epidemiological effects of these transgenic strategies are highly uncertain. If neither vaccines, medications, nor transgenic strategies can by themselves suffice for managing vector-borne diseases, integrating these approaches becomes key. Here we develop a framework to evaluate how clinical interventions (i.e., vaccination and medication can be integrated with transgenic vector manipulation strategies to prevent disease invasion and reduce disease incidence. We show that the ability of clinical interventions to accelerate disease suppression can depend on the nature of the transgenic manipulation deployed (e.g., whether vector population reduction or replacement is attempted. We find that making a specific, individual strategy highly effective may not be necessary for attaining public-health objectives, provided suitable combinations can be adopted. However, we show how combining only partially effective antimicrobial drugs or vaccination with transgenic vector manipulations that merely temporarily lower vector competence can amplify disease resurgence following transient suppression. Thus, transgenic vector manipulation that cannot be sustained can have adverse consequences-consequences which ineffective clinical interventions can at best only mitigate, and at worst temporarily exacerbate. This result, which arises from differences between the time scale on which the interventions affect disease dynamics and the time scale of host population dynamics, highlights the importance of accounting for the potential delay in the effects of deploying public health strategies on long-term disease incidence. We find that for systems at the disease-endemic equilibrium, even

Heterologous protein secretion in Lactobacilli with modified pSIP vectors.

Directory of Open Access Journals (Sweden)

Ingrid Lea Karlskås

Full Text Available We describe new variants of the modular pSIP-vectors for inducible gene expression and protein secretion in lactobacilli. The basic functionality of the pSIP system was tested in Lactobacillus strains representing 14 species using pSIP411, which harbors the broad-host-range Lactococcus lactis SH71rep replicon and a β-glucuronidase encoding reporter gene. In 10 species, the inducible gene expression system was functional. Based on these results, three pSIP vectors with different signal peptides were modified by replacing their narrow-host-range L. plantarum 256rep replicon with SH71rep and transformed into strains of five different species of Lactobacillus. All recombinant strains secreted the target protein NucA, albeit with varying production levels and secretion efficiencies. The Lp_3050 derived signal peptide generally resulted in the highest levels of secreted NucA. These modified pSIP vectors are useful tools for engineering a wide variety of Lactobacillus species.

Modeling the spread of vector-borne diseases on bipartite networks.

Directory of Open Access Journals (Sweden)

Donal Bisanzio

Full Text Available BACKGROUND: Vector-borne diseases for which transmission occurs exclusively between vectors and hosts can be modeled as spreading on a bipartite network. METHODOLOGY/PRINCIPAL FINDINGS: In such models the spreading of the disease strongly depends on the degree distribution of the two classes of nodes. It is sufficient for one of the classes to have a scale-free degree distribution with a slow enough decay for the network to have asymptotically vanishing epidemic threshold. Data on the distribution of Ixodes ricinus ticks on mice and lizards from two independent studies are well described by a scale-free distribution compatible with an asymptotically vanishing epidemic threshold. The commonly used negative binomial, instead, cannot describe the right tail of the empirical distribution. CONCLUSIONS/SIGNIFICANCE: The extreme aggregation of vectors on hosts, described by the power-law decay of the degree distribution, makes the epidemic threshold decrease with the size of the network and vanish asymptotically.

Getting genetic access to natural adenovirus genomes to explore vector diversity.

Science.gov (United States)

Zhang, Wenli; Ehrhardt, Anja

2017-10-01

Recombinant vectors based on the human adenovirus type 5 (HAdV5) have been developed and extensively used in preclinical and clinical studies for over 30 years. However, certain restrictions of HAdV5-based vectors have limited their clinical applications because they are rather inefficient in specifically transducing cells of therapeutic interest that lack the coxsackievirus and adenovirus receptor (CAR). Moreover, enhanced vector-associated toxicity and widespread preexisting immunity have been shown to significantly hamper the effectiveness of HAdV-5-mediated gene transfer. However, evolution of adenoviruses in the natural host is driving the generation of novel types with altered virulence, enhanced transmission, and altered tissue tropism. As a consequence, an increasing number of alternative adenovirus types were identified, which may represent a valuable resource for the development of novel vector types. Thus, researchers are focusing on the other naturally occurring adenovirus types, which are structurally similar but functionally different from HAdV5. To this end, several strategies have been devised for getting genetic access to adenovirus genomes, resulting in a new panel of adenoviral vectors. Importantly, these vectors were shown to have a host range different from HAdV5 and to escape the anti-HAdV5 immune response, thus underlining the great potential of this approach. In summary, this review provides a state-of-the-art overview of one essential step in adenoviral vector development.

Plant pathogen-induced volatiles attract parasitoids to increase parasitism of an insect vector

Directory of Open Access Journals (Sweden)

Xavier eMartini

2014-05-01

Full Text Available Interactions between plant pathogens and arthropods have been predominantly studied through the prism of herbivorous arthropods. Currently, little is known about the effect of plant pathogens on the third trophic level. This question is particularly interesting in cases where pathogens manipulate host phenotype to increase vector attraction and presumably increase their own proliferation. Indeed, a predator or a parasitoid of a vector may take advantage of this manipulated phenotype to increase its foraging performance. We explored the case of a bacterial pathogen, Candidatus Liberibacter asiaticus (Las, which modifies the odors released by its host plant (citrus trees to attract its vector, the psyllid Diaphorina citri. We found that the specialist parasitoid of D. citri, Tamarixia radiata, was attracted more toward Las-infected than uninfected plants. We demonstrated that this attractiveness was due to the release of methyl salicylate. Parasitization of D. citri nymphs on Las-infected plants was higher than on uninfected controls. Also, parasitization was higher on uninfected plants baited with methyl salicylate than on non-baited controls. This is the first report of a parasitoid ‘eavesdropping’ on a plant volatile induced by bacterial pathogen infection, which also increases effectiveness of host seeking behavior of its herbivorous vector.

Peptide Nucleic Acid Knockdown and Intra-host Cell Complementation of Ehrlichia Type IV Secretion System Effector

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Pratibha Sharma

2017-06-01

Full Text Available Survival of Ehrlichia chaffeensis depends on obligatory intracellular infection. One of the barriers to E. chaffeensis research progress has been the inability, using conventional techniques, to generate knock-out mutants for genes essential for intracellular infection. This study examined the use of Peptide Nucleic Acids (PNAs technology to interrupt type IV secretion system (T4SS effector protein expression in E. chaffeensis followed by intracellular complementation of the effector to determine its requirement for infection. Successful E. chaffeensis infection depends on the E. chaffeensis-specific T4SS protein effector, ehrlichial translocated factor-1 (Etf-1, which induces Rab5-regulated autophagy to provide host cytosolic nutrients required for E. chaffeensis proliferation. Etf-1 is also imported by host cell mitochondria where it inhibits host cell apoptosis to prolong its infection. We designed a PNA specific to Etf-1 and showed that the PNA bound to the target region of single-stranded Etf-1 RNA using a competitive binding assay. Electroporation of E. chaffeensis with this PNA significantly reduced Etf-1 mRNA and protein, and the bacteria's ability to induce host cell autophagy and infect host cells. Etf-1 PNA-mediated inhibition of ehrlichial Etf-1 expression and E. chaffeensis infection could be intracellularly trans-complemented by ectopic expression of Etf-1-GFP in host cells. These data affirmed the critical role of bacterial T4SS effector in host cell autophagy and E. chaffeensis infection, and demonstrated the use of PNA to analyze the gene functions of obligate intracellular bacteria.

Ferulic Acid, But Not All Hydroxycinnamic Acids, Is a Novel T3SS Inducer of Ralstonia solanacearum and Promotes Its Infection Process in Host Plants under Hydroponic Condition

Directory of Open Access Journals (Sweden)

Yong Zhang

2017-09-01

Full Text Available Hydroxycinnamic acids (HCAs are typical monocyclic phenylpropanoids, including cinnamic acid (Cin, coumaric acid (Cou, caffeic acid (Caf, ferulic acid (FA and their isomers, and involved in the interactions between pathogens and host plants. Here, we focused on the impact of HCAs on expression of type III secretion system (T3SS in Ralstonia solanacearum. FA significantly induced the expression of the T3SS and some type III effectors (T3Es genes in hrp-inducing medium, while did not the other HCAs. However, exogenously supplemented FA did not affect the T3SS expression in planta and the elicitation of the hypersensitive response (HR in tobacco leaves. Consistent with its central roles in pathogenicity, the FA-induced expression of the T3SS led to significant promotion on infection process of R. solanacearum in tomato plants under hydroponics cultivation. Moreover, the FA-induced expression of the T3SS was specifically mediated by the well-characterized signaling cascade PrhA-prhI/R-PrhJ-HrpG-HrpB, independent of the other known regulatory pathways. In summary, our results demonstrated that FA, a novel inducer of the T3SS in R. solanacearum, was able to promote its infection process in host plants under hydroponics condition.

Host-Derived Sialic Acids Are an Important Nutrient Source Required for Optimal Bacterial Fitness In Vivo

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Nathan D. McDonald

2016-04-01

Full Text Available A major challenge facing bacterial intestinal pathogens is competition for nutrient sources with the host microbiota. Vibrio cholerae is an intestinal pathogen that causes cholera, which affects millions each year; however, our knowledge of its nutritional requirements in the intestinal milieu is limited. In this study, we demonstrated that V. cholerae can grow efficiently on intestinal mucus and its component sialic acids and that a tripartite ATP-independent periplasmic SiaPQM strain, transporter-deficient mutant NC1777, was attenuated for colonization using a streptomycin-pretreated adult mouse model. In in vivo competition assays, NC1777 was significantly outcompeted for up to 3 days postinfection. NC1777 was also significantly outcompeted in in vitro competition assays in M9 minimal medium supplemented with intestinal mucus, indicating that sialic acid uptake is essential for fitness. Phylogenetic analyses demonstrated that the ability to utilize sialic acid was distributed among 452 bacterial species from eight phyla. The majority of species belonged to four phyla, Actinobacteria (members of Actinobacillus, Corynebacterium, Mycoplasma, and Streptomyces, Bacteroidetes (mainly Bacteroides, Capnocytophaga, and Prevotella, Firmicutes (members of Streptococcus, Staphylococcus, Clostridium, and Lactobacillus, and Proteobacteria (including Escherichia, Shigella, Salmonella, Citrobacter, Haemophilus, Klebsiella, Pasteurella, Photobacterium, Vibrio, and Yersinia species, mostly commensals and/or pathogens. Overall, our data demonstrate that the ability to take up host-derived sugars and sialic acid specifically allows V. cholerae a competitive advantage in intestinal colonization and that this is a trait that is sporadic in its occurrence and phylogenetic distribution and ancestral in some genera but horizontally acquired in others.

Hemocytes from Pediculus humanus humanus are hosts for human bacterial pathogens.

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Eric eGhigo

2015-01-01

Full Text Available Pediculus humanus humanus is an human ectoparasite which represents a serious public health threat because it is vector for pathogenic bacteria. It is important to understand and identify where bacteria reside in human body lice to define new strategies to counterstroke the capacity of vectorization of the bacterial pathogens by body lice. It is known that phagocytes from vertebrates can be hosts or reservoirs for several microbes. Therefore, we wondered if Pediculus humanus humanus phagocytes could hide pathogens. In this study, we characterized the phagocytes from Pediculus humanus humanus and evaluated their contribution as hosts for human pathogens such as Rickettsia prowazekii, Bartonella quintana and Acinetobacter baumannii.

Seasonal Abundance and Host-Feeding Patterns of Anopheline Vectors in Malaria Endemic Area of Iran

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Hamidreza Basseri

2010-01-01

Full Text Available Seasonal abundance and tendency to feed on humans are important parameters to measure for effective control of malaria vectors. The objective of this study was to describe relation between feeding pattern, abundance, and resting behavior of four malaria vectors in southern Iran. This study was conducted in ten indicator villages (based on malaria incidence and entomological indices in mountainous/hilly and plain regions situated south and southeastern Iran. Mosquito vectors were collected from indoor as well as outdoor shelters and the blood meals were examined by ELISA test. Over all 7654 female Anopheles spp. were captured, the most common species were Anopheles stephensi, An. culicifacies, An. fluviatilis, and An. d'thali. The overall human blood index was 37.50%, 19.83%, 16.4%, and 30.1% for An. fluviatilis, An. stephensi, An. culicifacies, and An. d'thali, respectively. In addition, An. fluviatilis fed on human blood during the entire year but the feeding behavior of An. stephensi and An. culicifacies varied according to seasons. Overall, the abundance of the female mosquito positive to human blood was 4.25% per human shelter versus 17.5% per animal shelter. This result indicates that the vectors had tendency to rest in animal shelters after feeding on human. Therefore, vector control measure should be planned based on such as feeding pattern, abundance, and resting behavior of these vectors in the area.

Ecology of Malaria Vectors in a Rainforest Suburban Community of ...

African Journals Online (AJOL)

User

2011-04-19

Apr 19, 2011 ... Key words: Malaria, Mosquito, Vectors, Ecology, Suburban, Community. ... including host bloodmeal preferences, time and place of biting and resting .... Five species of mosquitoes namely Aedes albopictus, Culex tigripes,.

Listeria monocytogenes as a vector for anti-cancer therapies.

LENUS (Irish Health Repository)

Tangney, Mark

2012-01-31

The intracellular pathogen Listeria monocytogenes represents a promising therapeutic vector for the delivery of DNA, RNA or protein to cancer cells or to prime immune responses against tumour-specific antigens. A number of biological properties make L. monocytogenes a promising platform for development as a vector for either gene therapy or as an anti-cancer vaccine vector. L. monocytogenes is particularly efficient in mediating internalization into host cells. Once inside cells, the bacterium produces specific virulence factors which lyse the vaculolar membrane and allow escape into the cytoplasm. Once in the cytosol, L. monocytogenes is capable of actin-based motility and cell-to-cell spread without an extracellular phase. The cytoplasmic location of L. monocytogenes is significant as this potentiates entry of antigens into the MHC Class I antigen processing pathway leading to priming of specific CD8(+) T cell responses. The cytoplasmic location is also beneficial for the delivery of DNA (bactofection) by L. monocytogenes whilst cell-to-cell spread may facilitate access of the vector to cells throughout the tumour. Several preclinical studies have demonstrated the ability of L. monocytogenes for intracellular gene or protein delivery in vitro and in vivo, and this vector has also displayed safety and efficacy in clinical trial. Here, we review the features of the L. monocytogenes host-pathogen interaction that make this bacterium such an attractive candidate with which to induce appropriate therapeutic responses. We focus primarily upon work that has led to attenuation of the pathogen, demonstrated DNA, RNA or protein delivery to tumour cells as well as research that shows the efficacy of L. monocytogenes as a vector for tumour-specific vaccine delivery.

Spatio-Temporal Distribution of Vector-Host Contact (VHC) Ratios and Ecological Niche Modeling of the West Nile Virus Mosquito Vector, Culex quinquefasciatus, in the City of New Orleans, LA, USA.

Science.gov (United States)

Sallam, Mohamed F; Michaels, Sarah R; Riegel, Claudia; Pereira, Roberto M; Zipperer, Wayne; Lockaby, B Graeme; Koehler, Philip G

2017-08-08

The consistent sporadic transmission of West Nile Virus (WNV) in the city of New Orleans justifies the need for distribution risk maps highlighting human risk of mosquito bites. We modeled the influence of biophysical and socioeconomic metrics on the spatio-temporal distributions of presence/vector-host contact (VHC) ratios of WNV vector, Culex quinquefasciatus , within their flight range . Biophysical and socioeconomic data were extracted within 5-km buffer radii around sampling localities of gravid female Culex quinquefasciatus . The spatio-temporal correlations between VHC data and 33 variables, including climate, land use-land cover (LULC), socioeconomic, and land surface terrain were analyzed using stepwise linear regression models (RM). Using MaxEnt, we developed a distribution model using the correlated predicting variables. Only 12 factors showed significant correlations with spatial distribution of VHC ratios ( R ² = 81.62, p < 0.01). Non-forested wetland (NFWL), tree density (TD) and residential-urban (RU) settings demonstrated the strongest relationship. The VHC ratios showed monthly environmental resilience in terms of number and type of influential factors. The highest prediction power of RU and other urban and built up land (OUBL), was demonstrated during May-August. This association was positively correlated with the onset of the mosquito WNV infection rate during June. These findings were confirmed by the Jackknife analysis in MaxEnt and independently collected field validation points. The spatial and temporal correlations of VHC ratios and their response to the predicting variables are discussed.

Mosquito-host interactions during and after an outbreak of equine viral encephalitis in Eastern Panama.

Directory of Open Access Journals (Sweden)

Wayra G Navia-Gine

Full Text Available Mosquito blood meals provide information about the feeding habits and host preference of potential arthropod-borne disease vectors. Although mosquito-borne diseases are ubiquitous in the Neotropics, few studies in this region have assessed patterns of mosquito-host interactions, especially during actual disease outbreaks. Based on collections made during and after an outbreak of equine viral encephalitis, we identified the source of 338 blood meals from 10 species of mosquitoes from Aruza Abajo, a location in Darien province in eastern Panama. A PCR based method targeting three distinct mitochondrial targets and subsequent DNA sequencing was used in an effort to delineate vector-host relationships. At Aruza Abajo, large domesticated mammals dominated the assemblage of mosquito blood meals while wild bird and mammal species represented only a small portion of the blood meal pool. Most mosquito species fed on a variety of hosts; foraging index analysis indicates that eight of nine mosquito species utilize hosts at similar proportions while a stochastic model suggests dietary overlap among species was greater than would be expected by chance. The results from our null-model analysis of mosquito diet overlap are consistent with the hypothesis that in landscapes where large domestic animals dominate the local biomass, many mosquito species show little host specificity, and feed upon hosts in proportion to their biomass, which may have implications for the role of livestocking patterns in vector-borne disease ecology.

Use of isotopes for research and control of vectors of animal diseases, host-pathogen relationships and the environmental impact of control procedures

Energy Technology Data Exchange (ETDEWEB)

NONE

1979-08-15

Full text: To cope with the world-wide problems of famine, malnutrition and environmental pollution it is imperative that all techniques and resources for the protection of animals and plants be utilized. As an example, nagana alone (animal trypanosomiasis) profoundly affects socioeconomic development in Africa. Its vector, the tsetse fly, is widespread and prevents agricultural development over much of the more than 7 million square kilometres where it is present. The need to control this disease has been emphasized by a mandate from the 1974 World Food Conference of the United Nations. If this disease alone could be eliminated, the cattle population could be increased by at least 120 million head with a resultant yearly increase in meat production of 1.5 million tons having a value totalling 750 million US dollars. The symposium was convened to discuss the various research and control aspects of nagana and related diseases and was the first of its kind to be convened by the sponsoring organizations The symposium amply demonstrated the value and usefulness of isotopes in the research and control of vectors of animal diseases, the elucidation of host-pathogen relationships and the degradation of pesticides. The symposium received an enthusiastic response, reflected in the large number of papers presented, which covered a variety of topics, including the sterile insect technique (SIT) as applied to tsetse flies. Several papers were presented covering its different aspects such as mass-rearing, sterility induction, ecology, behaviour and computer modelling. Other topics emphasized were pathogenesis and immunology of vector borne diseases such as trypanosomiasis, anaplasmosis, babesiosis and leishmaniasis. Also included were presentations on insect repellents and the biotransformation and degradation of labelled pesticides. The technical sessions began with 3 review papers, one on the FAO Animal Health Division's field research on tsetse flies, the second on the

Use of isotopes for research and control of vectors of animal diseases, host-pathogen relationships and the environmental impact of control procedures

International Nuclear Information System (INIS)

1979-01-01

Full text: To cope with the world-wide problems of famine, malnutrition and environmental pollution it is imperative that all techniques and resources for the protection of animals and plants be utilized. As an example, nagana alone (animal trypanosomiasis) profoundly affects socioeconomic development in Africa. Its vector, the tsetse fly, is widespread and prevents agricultural development over much of the more than 7 million square kilometres where it is present. The need to control this disease has been emphasized by a mandate from the 1974 World Food Conference of the United Nations. If this disease alone could be eliminated, the cattle population could be increased by at least 120 million head with a resultant yearly increase in meat production of 1.5 million tons having a value totalling 750 million US dollars. The symposium was convened to discuss the various research and control aspects of nagana and related diseases and was the first of its kind to be convened by the sponsoring organizations The symposium amply demonstrated the value and usefulness of isotopes in the research and control of vectors of animal diseases, the elucidation of host-pathogen relationships and the degradation of pesticides. The symposium received an enthusiastic response, reflected in the large number of papers presented, which covered a variety of topics, including the sterile insect technique (SIT) as applied to tsetse flies. Several papers were presented covering its different aspects such as mass-rearing, sterility induction, ecology, behaviour and computer modelling. Other topics emphasized were pathogenesis and immunology of vector borne diseases such as trypanosomiasis, anaplasmosis, babesiosis and leishmaniasis. Also included were presentations on insect repellents and the biotransformation and degradation of labelled pesticides. The technical sessions began with 3 review papers, one on the FAO Animal Health Division's field research on tsetse flies, the second on the

Weedy hosts and prevalence of potential leafhopper vectors (Hemiptera: Cicadellidae) of a phytoplasma (16SrIX group) associated with Huanglongbing symptoms in citrus groves.

Science.gov (United States)

Marques, R N; Teixeira, D C; Yamamoto, P T; Lopes, J R S

2012-04-01

Huanglongbing (HLB) is a severe citrus (Citrus spp.) disease associated with the bacteria genus Candidatus Liberibacter, detected in Brazil in 2004. Another bacterium was found in association with HLB symptoms and characterized as a phytoplasma belonging to the 16SrIX group. The objectives of this study were to identify potential leafhopper vectors of the HLB-associated phytoplasma and their host plants. Leafhoppers were sampled every other week for 12 mo with sticky yellow cards placed at two heights (0.3 and 1.5 m) in the citrus tree canopy and by using a sweep net in the ground vegetation of two sweet orange, Citrus sinensis (L.) Osbeck, groves infected by the HLB-phytoplasma in São Paulo state. Faunistic analyses indicated one Agalliinae (Agallia albidula Uhler) and three Deltocephalinae [Balclutha hebe (Kirkaldy), Planicephalus flavicosta (Stål), and Scaphytopius (Convelinus) marginelineatus (Stål)] species, as the most abundant and frequent leafhoppers (Hemiptera: Cicadellidae). Visual observations indicated an association of leafhopper species with some weeds and the influence of weed species composition on leafhopper abundance in low-lying vegetation. S. marginelineatus and P. flavicosta were more frequent on Sida rhombifolia L. and Althernantera tenella Colla, respectively, whereas A. albidula was observed more often on Conyza bonariensis (L.) Cronq. and B. hebe only occurred on grasses. DNA samples of field-collected S. marginelineatus were positive by polymerase chain reaction and sequencing tests for the presence of the HLB-phytoplasma group, indicating it as a potential vector. The association of leafhoppers with their hosts may be used in deciding which management strategies to adopt against weeds and diseases in citrus orchards.

Large-Scale Removal of Invasive Honeysuckle Decreases Mosquito and Avian Host Abundance.

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Gardner, Allison M; Muturi, Ephantus J; Overmier, Leah D; Allan, Brian F

2017-12-01

Invasive species rank second only to habitat destruction as a threat to native biodiversity. One consequence of biological invasions is altered risk of exposure to infectious diseases in human and animal populations. The distribution and prevalence of mosquito-borne diseases depend on the complex interactions between the vector, the pathogen, and the human or wildlife reservoir host. These interactions are highly susceptible to disturbance by invasive species, including terrestrial plants. We conducted a 2-year field experiment using a Before-After/Control-Impact design to examine how removal of invasive Amur honeysuckle (Lonicera maackii) in a forest fragment embedded within a residential neighborhood affects the abundance of mosquitoes, including two of the most important vectors of West Nile virus, Culex pipiens and Cx. restuans. We also assessed any potential changes in avian communities and local microclimate associated with Amur honeysuckle removal. We found that (1) removal of Amur honeysuckle reduces the abundance of both vector and non-vector mosquito species that commonly feed on human hosts, (2) the abundance and composition of avian hosts is altered by honeysuckle removal, and (3) areas invaded with honeysuckle support local microclimates that are favorable to mosquito survival. Collectively, our investigations demonstrate the role of a highly invasive understory shrub in determining the abundance and distribution of mosquitoes and suggest potential mechanisms underlying this pattern. Our results also give rise to additional questions regarding the general impact of invasive plants on vector-borne diseases and the spatial scale at which removal of invasive plants may be utilized to effect disease control.

AAV Vectorization of DSB-mediated Gene Editing Technologies.

Science.gov (United States)

Moser, Rachel J; Hirsch, Matthew L

2016-01-01

Recent work both at the bench and the bedside demonstrate zinc-finger nucleases (ZFNs), CRISPR/Cas9, and other programmable site-specific endonuclease technologies are being successfully utilized within and alongside AAV vectors to induce therapeutically relevant levels of directed gene editing within the human chromosome. Studies from past decades acknowledge that AAV vector genomes are enhanced substrates for homology-directed repair in the presence or absence of targeted DNA damage within the host genome. Additionally, AAV vectors are currently the most efficient format for in vivo gene delivery with no vector related complications in >100 clinical trials for diverse diseases. At the same time, advancements in the design of custom-engineered site-specific endonucleases and the utilization of elucidated endonuclease formats have resulted in efficient and facile genetic engineering for basic science and for clinical therapies. AAV vectors and gene editing technologies are an obvious marriage, using AAV for the delivery of repair substrate and/or a gene encoding a designer endonuclease; however, while efficient delivery and enhanced gene targeting by vector genomes are advantageous, other attributes of AAV vectors are less desirable for gene editing technologies. This review summarizes the various roles that AAV vectors play in gene editing technologies and provides insight into its trending applications for the treatment of genetic diseases.

[Vector transmitted diseases and climate changes in Europe].

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Rossati, Antonella; Bargiacchi, Olivia; Kroumova, Vesselina; Garavelli, Pietro Luigi

2014-09-01

The increase in temperatures recorded since the mid-nineteenth century is unprecedented in the history of mankind. The consequences of climate changes are numerous and can affect human health through direct (extreme events, natural disasters) or indirect (alteration of the ecosystem) mechanisms. Climate changes have repercussions on ecosystems, agriculture, social conditions, migration, conflicts and the transmission mode of infectious diseases. Vector-borne diseases are infections transmitted by the bite of infected arthropods such as mosquitoes, ticks, triatomines, sand flies and flies. Epidemiological cornerstones of vector-borne diseases are: the ecology and behaviour of the host, the ecology and behaviour of the vector, and the population's degree of immunity. Mosquito vectors related to human diseases mainly belong to the genus Culex, Aedes and Mansonia. Climate changes in Europe have increased the spread of new vectors, such as Aedes albopictus, and in some situations have made it possible to sustain the autochthonous transmission of some diseases (outbreak of Chukungunya virus in northern Italy in 2007, cases of dengue in the South of France and in Croatia). Despite the eradication of malaria from Europe, anopheline carriers are still present, and they may allow the transmission of the disease if the climatic conditions favour the development of the vectors and their contacts with plasmodium carriers. The tick Ixodes ricinus is a vector whose expansion has been documented both in latitude and in altitude in relation to the temperature increase; at the same time the related main viral and bacterial infections have increased. In northern Italy and Germany, the appearance of Leishmaniasis has been associated to climatic conditions that favour the development of the vector Phlebotomus papatasi and the maturation of the parasite within the vector, although the increase of cases of visceral leishmaniasis is also related to host immune factors, particularly

Quantifying and resolving multiple vector transformants in S. cerevisiae plasmid libraries.

Science.gov (United States)

Scanlon, Thomas C; Gray, Elizabeth C; Griswold, Karl E

2009-11-20

In addition to providing the molecular machinery for transcription and translation, recombinant microbial expression hosts maintain the critical genotype-phenotype link that is essential for high throughput screening and recovery of proteins encoded by plasmid libraries. It is known that Escherichia coli cells can be simultaneously transformed with multiple unique plasmids and thusly complicate recombinant library screening experiments. As a result of their potential to yield misleading results, bacterial multiple vector transformants have been thoroughly characterized in previous model studies. In contrast to bacterial systems, there is little quantitative information available regarding multiple vector transformants in yeast. Saccharomyces cerevisiae is the most widely used eukaryotic platform for cell surface display, combinatorial protein engineering, and other recombinant library screens. In order to characterize the extent and nature of multiple vector transformants in this important host, plasmid-born gene libraries constructed by yeast homologous recombination were analyzed by DNA sequencing. It was found that up to 90% of clones in yeast homologous recombination libraries may be multiple vector transformants, that on average these clones bear four or more unique mutant genes, and that these multiple vector cells persist as a significant proportion of library populations for greater than 24 hours during liquid outgrowth. Both vector concentration and vector to insert ratio influenced the library proportion of multiple vector transformants, but their population frequency was independent of transformation efficiency. Interestingly, the average number of plasmids born by multiple vector transformants did not vary with their library population proportion. These results highlight the potential for multiple vector transformants to dominate yeast libraries constructed by homologous recombination. The previously unrecognized prevalence and persistence of multiply

Quantifying and resolving multiple vector transformants in S. cerevisiae plasmid libraries

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Gray Elizabeth C

2009-11-01

Full Text Available Abstract Background In addition to providing the molecular machinery for transcription and translation, recombinant microbial expression hosts maintain the critical genotype-phenotype link that is essential for high throughput screening and recovery of proteins encoded by plasmid libraries. It is known that Escherichia coli cells can be simultaneously transformed with multiple unique plasmids and thusly complicate recombinant library screening experiments. As a result of their potential to yield misleading results, bacterial multiple vector transformants have been thoroughly characterized in previous model studies. In contrast to bacterial systems, there is little quantitative information available regarding multiple vector transformants in yeast. Saccharomyces cerevisiae is the most widely used eukaryotic platform for cell surface display, combinatorial protein engineering, and other recombinant library screens. In order to characterize the extent and nature of multiple vector transformants in this important host, plasmid-born gene libraries constructed by yeast homologous recombination were analyzed by DNA sequencing. Results It was found that up to 90% of clones in yeast homologous recombination libraries may be multiple vector transformants, that on average these clones bear four or more unique mutant genes, and that these multiple vector cells persist as a significant proportion of library populations for greater than 24 hours during liquid outgrowth. Both vector concentration and vector to insert ratio influenced the library proportion of multiple vector transformants, but their population frequency was independent of transformation efficiency. Interestingly, the average number of plasmids born by multiple vector transformants did not vary with their library population proportion. Conclusion These results highlight the potential for multiple vector transformants to dominate yeast libraries constructed by homologous recombination. The

Phytoplasma protein effector SAP11 enhances insect vector reproduction by manipulating plant development and defense hormone biosynthesis

OpenAIRE

Sugio, Akiko; Kingdom, Heather N.; MacLean, Allyson M.; Grieve, Victoria M.; Hogenhout, Saskia A.

2011-01-01

Phytoplasmas are insect-transmitted phytopathogenic bacteria that can alter plant morphology and the longevity and reproduction rates and behavior of their insect vectors. There are various examples of animal and plant parasites that alter the host phenotype to attract insect vectors, but it is unclear how these parasites accomplish this. We hypothesized that phytoplasmas produce effectors that modulate specific targets in their hosts leading to the changes in plant development and insect per...

Avipoxviruses: infection biology and their use as vaccine vectors.

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Weli, Simon C; Tryland, Morten

2011-02-03

Avipoxviruses (APVs) belong to the Chordopoxvirinae subfamily of the Poxviridae family. APVs are distributed worldwide and cause disease in domestic, pet and wild birds of many species. APVs are transmitted by aerosols and biting insects, particularly mosquitoes and arthropods and are usually named after the bird species from which they were originally isolated. The virus species Fowlpox virus (FWPV) causes disease in poultry and associated mortality is usually low, but in flocks under stress (other diseases, high production) mortality can reach up to 50%. APVs are also major players in viral vaccine vector development for diseases in human and veterinary medicine. Abortive infection in mammalian cells (no production of progeny viruses) and their ability to accommodate multiple gene inserts are some of the characteristics that make APVs promising vaccine vectors. Although abortive infection in mammalian cells conceivably represents a major vaccine bio-safety advantage, molecular mechanisms restricting APVs to certain hosts are not yet fully understood. This review summarizes the current knowledge relating to APVs, including classification, morphogenesis, host-virus interactions, diagnostics and disease, and also highlights the use of APVs as recombinant vaccine vectors.

Avipoxviruses: infection biology and their use as vaccine vectors

Directory of Open Access Journals (Sweden)

Tryland Morten

2011-02-01

Full Text Available Abstract Avipoxviruses (APVs belong to the Chordopoxvirinae subfamily of the Poxviridae family. APVs are distributed worldwide and cause disease in domestic, pet and wild birds of many species. APVs are transmitted by aerosols and biting insects, particularly mosquitoes and arthropods and are usually named after the bird species from which they were originally isolated. The virus species Fowlpox virus (FWPV causes disease in poultry and associated mortality is usually low, but in flocks under stress (other diseases, high production mortality can reach up to 50%. APVs are also major players in viral vaccine vector development for diseases in human and veterinary medicine. Abortive infection in mammalian cells (no production of progeny viruses and their ability to accommodate multiple gene inserts are some of the characteristics that make APVs promising vaccine vectors. Although abortive infection in mammalian cells conceivably represents a major vaccine bio-safety advantage, molecular mechanisms restricting APVs to certain hosts are not yet fully understood. This review summarizes the current knowledge relating to APVs, including classification, morphogenesis, host-virus interactions, diagnostics and disease, and also highlights the use of APVs as recombinant vaccine vectors.

Genetic modification of lymphocytes by retrovirus-based vectors.

Science.gov (United States)

Suerth, Julia D; Schambach, Axel; Baum, Christopher

2012-10-01

The genetic modification of lymphocytes is an important topic in the emerging field of gene therapy. Many clinical trials targeting immunodeficiency syndromes or cancer have shown therapeutic benefit; further applications address inflammatory and infectious disorders. Retroviral vector development requires a detailed understanding of the interactions with the host. Most researchers have used simple gammaretroviral vectors to modify lymphocytes, either directly or via hematopoietic stem and progenitor cells. Lentiviral, spumaviral (foamyviral) and alpharetroviral vectors were designed to reduce the necessity for cell stimulation and to utilize potentially safer integration properties. Novel surface modifications (pseudotyping) and transgenes, built using synthetic components, expand the retroviral toolbox, altogether promising increased specificity and potency. Product consistency will be an important criterion for routine clinical use. Copyright © 2012. Published by Elsevier Ltd.

Host Specificity of Salmonella typhimurium Deoxyribonucleic Acid Restriction and Modification

Science.gov (United States)

Slocum, Harvey; Boyer, Herbert W.

1973-01-01

The restriction and modification genes of Salmonella typhimurium which lie near the thr locus were transferred to a restrictionless mutant of Escherichia coli. These genes were found to be allelic to the E. coli K, B, and A restriction and modification genes. E. coli recombinants with the restriction and modification host specificity of S. typhimurium restricted phage λ that had been modified by each of the seven known host specificities of E. coli at efficiency of plating levels of about 10−2. Phage λ modified with the S. typhimurium host specificity was restricted by six of the seven E. coli host specificities but not by the RII (fi− R-factor controlled) host specificity. It is proposed that the restriction and modification enzymes of this S. typhimurium host specificity have two substrates, one of which is a substrate for the RII host specificity enzymes. PMID:4570605

Quantification of residual host cell DNA in adenoviral vectors produced on PER.C6 cells

NARCIS (Netherlands)

Gijsbers, Linda; Koel, Björn; Weggeman, Miranda; Goudsmit, Jaap; Havenga, Menzo; Marzio, Giuseppe

2005-01-01

Recombinant adenoviral vectors for gene therapy and vaccination are routinely prepared on cultures of immortalized cells, allowing the production of vector batches of high titer and consistent quality. Quantification of residual DNA from the producing cell line is part of the purity tests for

Analyzing the Genotoxicity of Retroviral Vectors in Hematopoietic Cell Gene Therapy

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Luca Biasco

2018-03-01

Full Text Available Retroviral vectors, including those derived from gammaretroviruses and lentiviruses, have found their way into the clinical arena and demonstrated remarkable efficacy for the treatment of immunodeficiencies, leukodystrophies, and globinopathies. Despite these successes, gene therapy unfortunately also has had to face severe adverse events in the form of leukemias and myelodysplastic syndromes, related to the semi-random vector integration into the host cell genome that caused deregulation of neighboring proto-oncogenes. Although improvements in vector design clearly lowered the risk of this insertional mutagenesis, analysis of potential genotoxicity and the consequences of vector integration remain important parameters for basic and translational research and most importantly for the clinic. Here, we review current assays to analyze biodistribution and genotoxicity in the pre-clinical setting and describe tools to monitor vector integration sites in vector-treated patients as a biosafety readout.

Fatty acids oxidation and alternative energy sources detected in Taenia crassiceps cysticerci after host treatment with antihelminthic drugs.

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Fraga, Carolina Miguel; Costa, Tatiane Luiza; Bezerra, José Clecildo Barreto; de Souza Lino Junior, Ruy; Vinaud, Marina Clare

2012-05-01

Human cysticercosis caused by Taenia crassiceps is rare however it is considered of zoonotic risk. The treatment of the infected patients was successful when using albendazole or praziquantel. The active forms of albendazole inhibit the glucose uptake and the active forms of praziquantel alter glycogen levels and nutrients absorption. The aim of this study was to analyze the production of organic acids that indicate the oxidation of fatty acids and the use of alternative energy sources from T. crassiceps cysticerci removed from the peritoneal cavity of mice treated with low dosages of albendazole (5.75 and 11.5mg/kg) or praziquantel (3.83 and 7.67 mg/kg). The beta-hydroxibutyrate production was higher by the larval stage cysticerci in all treated groups and the propionate production was higher in final stage cysticerci treated with 11.5mg/kg of albendazole when compared to the control group. The larval stages of cysticerci from the groups treated with 5.75 mg/kg of albendazole and 3.83 mg/kg of praziquantel produced more urea than the initial and final stages which indicate amino acids breakdown. We conclude that it was possible to detect the fatty acid oxidation and amino acids breakdown which indicate the use of alternative energy production sources as the used dosages only cause a partial blockage of the glucose uptake and leads to metabolic alterations in the cysticerci. The metabolic behavior observed after host treatment was different from former descriptions of the in vitro one which indicates great host-parasite interaction. Copyright © 2012 Elsevier Inc. All rights reserved.

Behavioural biology of Chagas disease vectors.

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Lazzari, Claudio Ricardo; Pereira, Marcos Horácio; Lorenzo, Marcelo Gustavo

2013-01-01

Many arthropod species have adopted vertebrate blood as their main food source. Blood is rich in nutrients and, except for the presence of parasites, sterile. However, this food source is not freely available, nor is obtaining it devoid of risk. It circulates inside vessels hidden underneath the skin of mobile hosts that are able to defend themselves and even predate the insects that try to feed on them. Thus, the haematophagous lifestyle is associated with major morphological, physiological and behavioural adaptations that have accumulated throughout the evolutionary history of the various lineages of blood-sucking arthropods. These adaptations have significant consequences for the evolution of parasites as well as for the epidemiology of vector-transmitted diseases. In this review article, we analyse various aspects of the behaviour of triatomine bugs to illustrate how each behavioural trait represents a particular adaptation to their close association with their hosts, which may easily turn into predators. Our aim is to offer to the reader an up-to-date integrative perspective on the behaviour of Chagas disease vectors and to propose new research avenues to encourage both young and experienced colleagues to explore this aspect of triatomine biology.

Behavioural biology of Chagas disease vectors

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Claudio Ricardo Lazzari

2013-01-01

Full Text Available Many arthropod species have adopted vertebrate blood as their main food source. Blood is rich in nutrients and, except for the presence of parasites, sterile. However, this food source is not freely available, nor is obtaining it devoid of risk. It circulates inside vessels hidden underneath the skin of mobile hosts that are able to defend themselves and even predate the insects that try to feed on them. Thus, the haematophagous lifestyle is associated with major morphological, physiological and behavioural adaptations that have accumulated throughout the evolutionary history of the various lineages of blood-sucking arthropods. These adaptations have significant consequences for the evolution of parasites as well as for the epidemiology of vector-transmitted diseases. In this review article, we analyse various aspects of the behaviour of triatomine bugs to illustrate how each behavioural trait represents a particular adaptation to their close association with their hosts, which may easily turn into predators. Our aim is to offer to the reader an up-to-date integrative perspective on the behaviour of Chagas disease vectors and to propose new research avenues to encourage both young and experienced colleagues to explore this aspect of triatomine biology.

Altering the selection capabilities of common cloning vectors via restriction enzyme mediated gene disruption

Science.gov (United States)

2013-01-01

Background The cloning of gene sequences forms the basis for many molecular biological studies. One important step in the cloning process is the isolation of bacterial transformants carrying vector DNA. This involves a vector-encoded selectable marker gene, which in most cases, confers resistance to an antibiotic. However, there are a number of circumstances in which a different selectable marker is required or may be preferable. Such situations can include restrictions to host strain choice, two phase cloning experiments and mutagenesis experiments, issues that result in additional unnecessary cloning steps, in which the DNA needs to be subcloned into a vector with a suitable selectable marker. Results We have used restriction enzyme mediated gene disruption to modify the selectable marker gene of a given vector by cloning a different selectable marker gene into the original marker present in that vector. Cloning a new selectable marker into a pre-existing marker was found to change the selection phenotype conferred by that vector, which we were able to demonstrate using multiple commonly used vectors and multiple resistance markers. This methodology was also successfully applied not only to cloning vectors, but also to expression vectors while keeping the expression characteristics of the vector unaltered. Conclusions Changing the selectable marker of a given vector has a number of advantages and applications. This rapid and efficient method could be used for co-expression of recombinant proteins, optimisation of two phase cloning procedures, as well as multiple genetic manipulations within the same host strain without the need to remove a pre-existing selectable marker in a previously genetically modified strain. PMID:23497512

Environmental Drivers of Seasonal Patterns of Host Utilization by Culiseta melanura (Diptera: Culicidae) in Florida.

Science.gov (United States)

Blosser, Erik M; Lord, Cynthia C; Stenn, Tanise; Acevedo, Carolina; Hassan, Hassan K; Reeves, Lawrence E; Unnasch, Thomas R; Burkett-Cadena, Nathan D

2017-09-01

Field studies were carried out in four Florida counties to investigate winter and spring ecology of host use by Culiseta melanura (Coquillet), the primary vector of eastern equine encephalomyelitis virus (EEEV) in North America. Bloodmeal analysis by PCR was used to identify 233 host bloodmeals, which mainly originated from birds (78.5%) and reptiles (17.2%), primarily Anolis spp. lizards. Across counties, the percentage of bloodmeals from reptiles (7-37% depending upon county) increased with increasing day length and temperature in the spring. Multiple logistic regression revealed that differences in reptile host use across collection sites were largely explained by differences in average day length and temperature on the day of collection, and is probably owing to environment-driven behavioral patterns of ectothermic animals. Although past studies have demonstrated reptile biting by epizootic vectors of EEEV, including Culex (Melanoconion) spp., this is the first study to demonstrate widespread and common feeding upon ectothermic hosts by Cs. melanura. This work suggests that reptiles, particularly anole lizards, play a role in the ecology of EEEV in Florida either as amplifying hosts or as noncompetent hosts which dilute vector feedings thereby suppressing transmission. Detailed laboratory studies investigating impacts of environmental variables (temperature and photoperiod) on EEEV competence of anoles are needed to assess whether these animals support virus amplification. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

[Micronecta sp (Corixidae) and Diplonychus sp (Belostomatidae), two aquatic Hemiptera hosts and/or potential vectors of Mycobacterium ulcerans (pathogenic agent of Buruli ulcer) in Cote d'Ivoire].

Science.gov (United States)

Doannio, J M C; Konan, K L; Dosso, F N; Koné, A B; Konan, Y L; Sankaré, Y; Ekaza, E; Coulibaly, N D; Odéhouri, K P; Dosso, M; Sess, E D; Marsollier, L; Aubry, J

2011-02-01

Buruli ulcer is currently a major public health problem in Côte d'Ivoire. It is a neglected tropical disease closely associated with aquatic environments. Aquatic insects of the Hemiptera order have been implicated in human transmission of Mycobacterium ulcerans, the pathogenic agent of Buruli ulcer. The purpose of this preliminary study using the polymerase chain reaction (PCR) method was to evaluate aquatic insects in Sokrogbo, a village in the Tiassalé sanitary district where Buruli ulcer is endemic. Findings identified two water bugs hosting Mycobacterium ulcerans, i.e., one of the Micronecta genus in the Corixidae family and another of the Diplonychus genus in the Belostomatidae family. The PCR technique used revealed the molecular signatures of M. ulcerans in tissue from these two insects. Based on these findings, these two water bugs can be considered as potential hosts and/or vectors of M. ulcerans in the study zone. Unlike Diplonychus sp., this is the first report to describe Micronecta sp as a host of M. ulcerans. Further investigation will be needed to assess the role of these two water bugs in human transmission of M. ulcerans in Côte d'Ivoire.

Stage-Specific Changes in Plasmodium Metabolism Required for Differentiation and Adaptation to Different Host and Vector Environments.

Science.gov (United States)

Srivastava, Anubhav; Philip, Nisha; Hughes, Katie R; Georgiou, Konstantina; MacRae, James I; Barrett, Michael P; Creek, Darren J; McConville, Malcolm J; Waters, Andrew P

2016-12-01

Malaria parasites (Plasmodium spp.) encounter markedly different (nutritional) environments during their complex life cycles in the mosquito and human hosts. Adaptation to these different host niches is associated with a dramatic rewiring of metabolism, from a highly glycolytic metabolism in the asexual blood stages to increased dependence on tricarboxylic acid (TCA) metabolism in mosquito stages. Here we have used stable isotope labelling, targeted metabolomics and reverse genetics to map stage-specific changes in Plasmodium berghei carbon metabolism and determine the functional significance of these changes on parasite survival in the blood and mosquito stages. We show that glutamine serves as the predominant input into TCA metabolism in both asexual and sexual blood stages and is important for complete male gametogenesis. Glutamine catabolism, as well as key reactions in intermediary metabolism and CoA synthesis are also essential for ookinete to oocyst transition in the mosquito. These data extend our knowledge of Plasmodium metabolism and point towards possible targets for transmission-blocking intervention strategies. Furthermore, they highlight significant metabolic differences between Plasmodium species which are not easily anticipated based on genomics or transcriptomics studies and underline the importance of integration of metabolomics data with other platforms in order to better inform drug discovery and design.

Stage-Specific Changes in Plasmodium Metabolism Required for Differentiation and Adaptation to Different Host and Vector Environments.

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Anubhav Srivastava

2016-12-01

Full Text Available Malaria parasites (Plasmodium spp. encounter markedly different (nutritional environments during their complex life cycles in the mosquito and human hosts. Adaptation to these different host niches is associated with a dramatic rewiring of metabolism, from a highly glycolytic metabolism in the asexual blood stages to increased dependence on tricarboxylic acid (TCA metabolism in mosquito stages. Here we have used stable isotope labelling, targeted metabolomics and reverse genetics to map stage-specific changes in Plasmodium berghei carbon metabolism and determine the functional significance of these changes on parasite survival in the blood and mosquito stages. We show that glutamine serves as the predominant input into TCA metabolism in both asexual and sexual blood stages and is important for complete male gametogenesis. Glutamine catabolism, as well as key reactions in intermediary metabolism and CoA synthesis are also essential for ookinete to oocyst transition in the mosquito. These data extend our knowledge of Plasmodium metabolism and point towards possible targets for transmission-blocking intervention strategies. Furthermore, they highlight significant metabolic differences between Plasmodium species which are not easily anticipated based on genomics or transcriptomics studies and underline the importance of integration of metabolomics data with other platforms in order to better inform drug discovery and design.

Differential profiles of direct and indirect modification of vector feeding behaviour by a plant virus.

Science.gov (United States)

He, Wen-Bo; Li, Jie; Liu, Shu-Sheng

2015-01-08

Plant viruses interact with their insect vectors directly and indirectly via host plants, and this tripartite interaction may produce fitness benefits to both the vectors and the viruses. Our previous studies show that the Middle East-Asia Minor 1 (MEAM1) species of the whitefly Bemisia tabaci complex improved its performance on tobacco plants infected by the Tomato yellow leaf curl China virus (TYLCCNV), which it transmits, although virus infection of the whitefly per se reduced its performance. Here, we use electrical penetration graph recording to investigate the direct and indirect effects of TYLCCNV on the feeding behaviour of MEAM1. When feeding on either cotton, a non-host of TYLCCNV, or uninfected tobacco, a host of TYLCCNV, virus-infection of the whiteflies impeded their feeding. Interestingly, when viruliferous whiteflies fed on virus-infected tobacco, their feeding activities were no longer negatively affected; instead, the virus promoted whitefly behaviour related to rapid and effective sap ingestion. Our findings show differential profiles of direct and indirect modification of vector feeding behaviour by a plant virus, and help to unravel the behavioural mechanisms underlying a mutualistic relationship between an insect vector and a plant virus that also has features reminiscent of an insect pathogen.

Short chain and polyunsaturated fatty acids in host gut health and foodborne bacterial pathogen inhibition.

Science.gov (United States)

Peng, Mengfei; Biswas, Debabrata

2017-12-12

As a major source of microbes and their numerous beneficial effects, the gut microflora/microbiome is intimately linked to human health and disease. The exclusion of enteric pathogens by these commensal microbes partially depends upon the production of bioactive compounds such as short-chain fatty acids (SCFAs) and polyunsaturated fatty acids (PUFAs). These key intestinal microbial byproducts are crucial to the maintenance of a healthy gut microbial community. Moreover, SCFAs and PUFAs play multiple critical roles in host defense and immunity, including anti-cancer, anti-inflammation, and anti-oxidant activities, as well as out-competition of enteric bacterial pathogens. In this review article, we hereby aim to highlight the importance of SCFAs and PUFAs and the microbes involved in production of these beneficial intestinal components, and their biological functions, specifically as to their immunomodulation and interactions with enteric bacterial pathogens. Finally, we also advance potential applications of these fatty acids with regards to food safety and human gut health.

Complex interactions among host pines and fungi vectored by an invasive bark beetle

Science.gov (United States)

Min Lu; Michael J. Wingfield; Nancy E. Gillette; Sylvia R. Mori; Jian-Hua Sun

2010-01-01

Recent studies have investigated the relationships between pairs or groups of exotic species to illustrate invasive mechanisms, but most have focused on interactions at a single trophic level.Here, we conducted pathogenicity tests, analyses of host volatiles and fungal growth tests to elucidate an intricate network of interactions between the host...

Enforcing host cell polarity: an apicomplexan parasite strategy towards dissemination.

Science.gov (United States)

Baumgartner, Martin

2011-08-01

The propagation of apicomplexan parasites through transmitting vectors is dependent on effective dissemination of parasites inside the mammalian host. Intracellular Toxoplasma and Theileria parasites face the challenge that their spread inside the host depends in part on the motile capacities of their host cells. In response, these parasites influence the efficiency of dissemination by altering adhesive and/or motile properties of their host cells. Theileria parasites do so by targeting signalling pathways that control host cell actin dynamics. The resulting enforced polar host cell morphology facilitates motility and invasiveness, by establishing focal adhesion and invasion structures at the leading edge of the infected cell. This parasite strategy highlights mechanisms of motility regulation that are also likely relevant for immune or cancer cell motility. Copyright © 2011 Elsevier Ltd. All rights reserved.

Triatominae-Trypanosoma cruzi/T. rangeli: Vector-parasite interactions.

Science.gov (United States)

Vallejo, G A; Guhl, F; Schaub, G A

2009-01-01

Of the currently known 140 species in the family Reduviidae, subfamily Triatominae, those which are most important as vectors of the aetiologic agent of Chagas disease, Trypanosoma cruzi, belong to the tribes Triatomini and Rhodniini. The latter not only transmit T. cruzi but also Trypanosoma rangeli, which is considered apathogenic for the mammalian host but can be pathogenic for the vectors. Using different molecular methods, two main lineages of T. cruzi have been classified, T. cruzi I and T. cruzi II. Within T. cruzi II, five subdivisions are recognized, T. cruzi IIa-IIe, according to the variability of the ribosomal subunits 24Salpha rRNA and 18S rRNA. In T. rangeli, differences in the organization of the kinetoplast DNA separate two forms denoted T. rangeli KP1+ and KP1-, although differences in the intergenic mini-exon gene and of the small subunit rRNA (SSU rRNA) suggest four subpopulations denoted T. rangeli A, B, C and D. The interactions of these subpopulations of the trypanosomes with different species and populations of Triatominae determine the epidemiology of the human-infecting trypanosomes in Latin America. Often, specific subpopulations of the trypanosomes are transmitted by specific vectors in a particular geographic area. Studies centered on trypanosome-triatomine interaction may allow identification of co-evolutionary processes, which, in turn, could consolidate hypotheses of the evolution and the distribution of T. cruzi/T. rangeli-vectors in America, and they may help to identify the mechanisms that either facilitate or impede the transmission of the parasites in different vector species. Such mechanisms seem to involve intestinal bacteria, especially the symbionts which are needed by the triatomines to complete nymphal development and to produce eggs. Development of the symbionts is regulated by the vector. T. cruzi and T. rangeli interfere with this system and induce the production of antibacterial substances. Whereas T. cruzi is only

Vectorization of Nucleic Acids for Therapeutic Approach: Tutorial Review.

Science.gov (United States)

Geinguenaud, Frederic; Guenin, Erwann; Lalatonne, Yoann; Motte, Laurence

2016-05-20

Oligonucleotides present a high therapeutic potential for a wide variety of diseases. However, their clinical development is limited by their degradation by nucleases and their poor blood circulation time. Depending on the administration mode and the cellular target, these macromolecules will have to cross the vascular endothelium, to diffuse through the extracellular matrix, to be transported through the cell membrane, and finally to reach the cytoplasm. To overcome these physiological barriers, many strategies have been developed. Here, we review different methods of DNA vectorization, discuss limitations and advantages of the various vectors, and provide new perspectives for future development.

Broad patterns in domestic vector-borne Trypanosoma cruzi transmission dynamics: synanthropic animals and vector control.

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Peterson, Jennifer K; Bartsch, Sarah M; Lee, Bruce Y; Dobson, Andrew P

2015-10-22

Chagas disease (caused by Trypanosoma cruzi) is the most important neglected tropical disease (NTD) in Latin America, infecting an estimated 5.7 million people in the 21 countries where it is endemic. It is one of the NTDs targeted for control and elimination by the 2020 London Declaration goals, with the first goal being to interrupt intra-domiciliary vector-borne T. cruzi transmission. A key question in domestic T. cruzi transmission is the role that synanthropic animals play in T. cruzi transmission to humans. Here, we ask, (1) do synanthropic animals need to be targeted in Chagas disease prevention policies?, and (2) how does the presence of animals affect the efficacy of vector control? We developed a simple mathematical model to simulate domestic vector-borne T. cruzi transmission and to specifically examine the interaction between the presence of synanthropic animals and effects of vector control. We used the model to explore how the interactions between triatomine bugs, humans and animals impact the number and proportion of T. cruzi-infected bugs and humans. We then examined how T. cruzi dynamics change when control measures targeting vector abundance are introduced into the system. We found that the presence of synanthropic animals slows the speed of T. cruzi transmission to humans, and increases the sensitivity of T. cruzi transmission dynamics to vector control measures at comparable triatomine carrying capacities. However, T. cruzi transmission is amplified when triatomine carrying capacity increases with the abundance of syntathoropic hosts. Our results suggest that in domestic T. cruzi transmission scenarios where no vector control measures are in place, a reduction in synanthropic animals may slow T. cruzi transmission to humans, but it would not completely eliminate transmission. To reach the 2020 goal of interrupting intra-domiciliary T. cruzi transmission, it is critical to target vector populations. Additionally, where vector control measures

Baculovirus expression vector system: An efficient tool for the ...

African Journals Online (AJOL)

Baculovirus expression vector system is considered one of the most successful and widely acceptable means for the production of recombinant proteins in extremely large quantities. Proper posttranslational modifications of the expressed proteins in insect cells, the usual host of baculoviruses, get them soluble, correctly ...

Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting.

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Clement N Mweya

Full Text Available Rift Valley Fever (RVF is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics.Time-varying distributed delays (TVDD and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district.Findings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.

Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting.

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Mweya, Clement N; Holst, Niels; Mboera, Leonard E G; Kimera, Sharadhuli I

2014-01-01

Rift Valley Fever (RVF) is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics. Time-varying distributed delays (TVDD) and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML) files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district. Findings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.

Studies on avian malaria in vectors and hosts of encephalitis in Kern County, California. I. Infections in avian hosts

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Herman, C.M.; Reeves, W.C.; McClure, H.E.; French, E.M.; Hammon, W.M.

1954-01-01

An epizoological study of Plasmodium infections in wild birds of Kern County, California, in the years 1946 through 1951 greatly extended knowledge of the occurrence of these parasites and their behavior in nature. Examination of 10,459 blood smears from 8,674 birds representing 73 species resulted in the observation of Plasmodium spp. in 1,094 smears representing 888 individual birds of 27 species. Seven species of Plasmodium were found: relictum, elongatum, hexamerium, nucleophilum, polare, rouxi and vaughani. Plasmodium relictum was by far the most frequently observed species, occurring in at least 79 per cent of the infected birds. Twelve new host species are recorded for this parasite. Sufficient morphological variation was observed to indicate that two strains of this species probably exist in nature. Numerous new host records were made of plasmodia with elongate gametocytes. The finding of parasites believed to be P. rouxi in two new host species represents the first record of the occurrence of this Plasmodium outside of Algeria. Multiple smears were obtained from a number of individual birds over varying time periods. Evidence of prolonged parasitemia was unusual, but some individuals had parasitemia on consecutive months and even for three successive years. In most individuals, parasitemias were of short duration. The inoculation of blood from wild birds into canaries led to the demonstration of many infections not observed on blood smear examination of donors. Use of these two complementary techniques led to more complete host records and a truer picture of the prevalence of infection. Three age classes of birds were studied--nestling, immature (less than 1 year of age) and adult. Parasites were observed in all three groups but infections in the younger individuals were most susceptible to interpretation. As to time of onset, numerous records were obtained of infection in nestling birds. Prevalence rates in immature birds after a single season's exposure

An introduction to vectors, vector operators and vector analysis

CERN Document Server

Joag, Pramod S

2016-01-01

Ideal for undergraduate and graduate students of science and engineering, this book covers fundamental concepts of vectors and their applications in a single volume. The first unit deals with basic formulation, both conceptual and theoretical. It discusses applications of algebraic operations, Levi-Civita notation, and curvilinear coordinate systems like spherical polar and parabolic systems and structures, and analytical geometry of curves and surfaces. The second unit delves into the algebra of operators and their types and also explains the equivalence between the algebra of vector operators and the algebra of matrices. Formulation of eigen vectors and eigen values of a linear vector operator are elaborated using vector algebra. The third unit deals with vector analysis, discussing vector valued functions of a scalar variable and functions of vector argument (both scalar valued and vector valued), thus covering both the scalar vector fields and vector integration.

Host-Derived Sialic Acids Are an Important Nutrient Source Required for Optimal Bacterial Fitness In Vivo.

Science.gov (United States)

McDonald, Nathan D; Lubin, Jean-Bernard; Chowdhury, Nityananda; Boyd, E Fidelma

2016-04-12

A major challenge facing bacterial intestinal pathogens is competition for nutrient sources with the host microbiota.Vibrio cholerae is an intestinal pathogen that causes cholera, which affects millions each year; however, our knowledge of its nutritional requirements in the intestinal milieu is limited. In this study, we demonstrated that V. cholerae can grow efficiently on intestinal mucus and its component sialic acids and that a tripartite ATP-independent periplasmic SiaPQM strain, transporter-deficient mutant NC1777, was attenuated for colonization using a streptomycin-pretreated adult mouse model. In in vivo competition assays, NC1777 was significantly outcompeted for up to 3 days postinfection. NC1777 was also significantly outcompeted in in vitro competition assays in M9 minimal medium supplemented with intestinal mucus, indicating that sialic acid uptake is essential for fitness. Phylogenetic analyses demonstrated that the ability to utilize sialic acid was distributed among 452 bacterial species from eight phyla. The majority of species belonged to four phyla, Actinobacteria (members of Actinobacillus, Corynebacterium, Mycoplasma, and Streptomyces), Bacteroidetes (mainly Bacteroides, Capnocytophaga, and Prevotella), Firmicutes (members of Streptococcus, Staphylococcus, Clostridium, and Lactobacillus), and Proteobacteria (including Escherichia, Shigella, Salmonella, Citrobacter, Haemophilus, Klebsiella, Pasteurella, Photobacterium, Vibrio, and Yersinia species), mostly commensals and/or pathogens. Overall, our data demonstrate that the ability to take up host-derived sugars and sialic acid specifically allows V. cholerae a competitive advantage in intestinal colonization and that this is a trait that is sporadic in its occurrence and phylogenetic distribution and ancestral in some genera but horizontally acquired in others. Sialic acids are nine carbon amino sugars that are abundant on all mucous surfaces. The deadly human pathogen Vibrio cholerae contains

Generation Of Multicopy Pichia Clones From Gap Vector | Ekwenye ...

African Journals Online (AJOL)

The methylotrophic yeast Pichia pastoris was used as a host to generate multicopy clones using in-vitro multimerization and GAP vector approaches. The latter approach relied on the selection of spontaneously occurring multiple integrants based on zeocin resistance. Higher levels of heterologous protein could result using ...

Genome Investigations of Vector Competence in Aedes aegypti to Inform Novel Arbovirus Disease Control Approaches

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David W. Severson

2016-10-01

Full Text Available Dengue (DENV, yellow fever, chikungunya, and Zika virus transmission to humans by a mosquito host is confounded by both intrinsic and extrinsic variables. Besides virulence factors of the individual arboviruses, likelihood of virus transmission is subject to variability in the genome of the primary mosquito vector, Aedes aegypti. The “vectorial capacity” of A. aegypti varies depending upon its density, biting rate, and survival rate, as well as its intrinsic ability to acquire, host and transmit a given arbovirus. This intrinsic ability is known as “vector competence”. Based on whole transcriptome analysis, several genes and pathways have been predicated to have an association with a susceptible or refractory response in A. aegypti to DENV infection. However, the functional genomics of vector competence of A. aegypti is not well understood, primarily due to lack of integrative approaches in genomic or transcriptomic studies. In this review, we focus on the present status of genomics studies of DENV vector competence in A. aegypti as limited information is available relative to the other arboviruses. We propose future areas of research needed to facilitate the integration of vector and virus genomics and environmental factors to work towards better understanding of vector competence and vectorial capacity in natural conditions.

Foamy Virus Biology and Its Application for Vector Development

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Axel Rethwilm

2011-05-01

Full Text Available Spuma- or foamy viruses (FV, endemic in most non-human primates, cats, cattle and horses, comprise a special type of retrovirus that has developed a replication strategy combining features of both retroviruses and hepadnaviruses. Unique features of FVs include an apparent apathogenicity in natural hosts as well as zoonotically infected humans, a reverse transcription of the packaged viral RNA genome late during viral replication resulting in an infectious DNA genome in released FV particles and a special particle release strategy depending capsid and glycoprotein coexpression and specific interaction between both components. In addition, particular features with respect to the integration profile into the host genomic DNA discriminate FV from orthoretroviruses. It appears that some inherent properties of FV vectors set them favorably apart from orthoretroviral vectors and ask for additional basic research on the viruses as well as on the application in Gene Therapy. This review will summarize the current knowledge of FV biology and the development as a gene transfer system.

Diverse amino acid changes at specific positions in the N-terminal region of the coat protein allow Plum pox virus to adapt to new hosts.

Science.gov (United States)

Carbonell, Alberto; Maliogka, Varvara I; Pérez, José de Jesús; Salvador, Beatriz; León, David San; García, Juan Antonio; Simón-Mateo, Carmen

2013-10-01

Plum pox virus (PPV)-D and PPV-R are two isolates from strain D of PPV that differ in host specificity. Previous analyses of chimeras originating from PPV-R and PPV-D suggested that the N terminus of the coat protein (CP) includes host-specific pathogenicity determinants. Here, these determinants were mapped precisely by analyzing the infectivity in herbaceous and woody species of chimeras containing a fragment of the 3' region of PPV-D (including the region coding for the CP) in a PPV-R backbone. These chimeras were not infectious in Prunus persica, but systemically infected Nicotiana clevelandii and N. benthamiana when specific amino acids were modified or deleted in a short 30-amino-acid region of the N terminus of the CP. Most of these mutations did not reduce PPV fitness in Prunus spp. although others impaired systemic infection in this host. We propose a model in which the N terminus of the CP, highly relevant for virus systemic movement, is targeted by a host defense mechanism in Nicotiana spp. Mutations in this short region allow PPV to overcome the defense response in this host but can compromise the efficiency of PPV systemic movement in other hosts such as Prunus spp.

Host and Symbiont Jointly Control Gut Microbiota during Complete Metamorphosis

Science.gov (United States)

Johnston, Paul R.; Rolff, Jens

2015-01-01

Holometabolous insects undergo a radical anatomical re-organisation during metamorphosis. This poses a developmental challenge: the host must replace the larval gut but at the same time retain symbiotic gut microbes and avoid infection by opportunistic pathogens. By manipulating host immunity and bacterial competitive ability, we study how the host Galleria mellonella and the symbiotic bacterium Enterococcus mundtii interact to manage the composition of the microbiota during metamorphosis. Disenabling one or both symbiotic partners alters the composition of the gut microbiota, which incurs fitness costs: adult hosts with a gut microbiota dominated by pathogens such as Serratia and Staphylococcus die early. Our results reveal an interaction that guarantees the safe passage of the symbiont through metamorphosis and benefits the resulting adult host. Host-symbiont “conspiracies” as described here are almost certainly widespread in holometobolous insects including many disease vectors. PMID:26544881

Transgene Expression and Host Cell Responses to Replication-Defective, Single-Cycle, and Replication-Competent Adenovirus Vectors

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Catherine M. Crosby

2017-02-01

Full Text Available Most adenovirus (Ad vectors are E1 gene deleted replication defective (RD-Ad vectors that deliver one transgene to the cell and all expression is based on that one gene. In contrast, E1-intact replication-competent Ad (RC-Ad vectors replicate their DNA and their transgenes up to 10,000-fold, amplifying transgene expression markedly higher than RD-Ad vectors. While RC-Ad are more potent, they run the real risk of causing adenovirus infections in vector recipients and those that administer them. To gain the benefits of transgene amplification, but avoid the risk of Ad infections, we developed “single cycle” Ad (SC-Ad vectors. SC-Ads amplify transgene expression and generated markedly stronger and more persistent immune responses than RD-Ad as expected. However, they also unexpectedly generated stronger immune responses than RC-Ad vectors. To explore the basis of this potency here, we compared gene expression and the cellular responses to infection to these vectors in vitro and in vivo. In vitro, in primary human lung epithelial cells, SC- and RC-Ad amplified their genomes more than 400-fold relative to RD-Ad with higher replication by SC-Ad. This replication translated into higher green fluorescent protein (GFP expression for 48 h by SC- and RC-Ad than by RD-Ad. In vitro, in the absence of an immune system, RD-Ad expression became higher by 72 h coincident with cell death mediated by SC- and RC-Ad and release of transgene product from the dying cells. When the vectors were compared in human THP-1 Lucia- interferon-stimulated gene (ISG cells, which are a human monocyte cell line that have been modified to quantify ISG activity, RC-Ad6 provoked significantly stronger ISG responses than RD- or SC-Ad. In mice, intravenous or intranasal injection produced up to 100-fold genome replication. Under these in vivo conditions in the presence of the immune system, luciferase expression by RC and SC-Ad was markedly higher than that by RD-Ad. In

Phytoplasma protein effector SAP11 enhances insect vector reproduction by manipulating plant development and defense hormone biosynthesis.

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Sugio, Akiko; Kingdom, Heather N; MacLean, Allyson M; Grieve, Victoria M; Hogenhout, Saskia A

2011-11-29

Phytoplasmas are insect-transmitted phytopathogenic bacteria that can alter plant morphology and the longevity and reproduction rates and behavior of their insect vectors. There are various examples of animal and plant parasites that alter the host phenotype to attract insect vectors, but it is unclear how these parasites accomplish this. We hypothesized that phytoplasmas produce effectors that modulate specific targets in their hosts leading to the changes in plant development and insect performance. Previously, we sequenced and mined the genome of Aster Yellows phytoplasma strain Witches' Broom (AY-WB) and identified 56 candidate effectors. Here, we report that the secreted AY-WB protein 11 (SAP11) effector modulates plant defense responses to the advantage of the AY-WB insect vector Macrosteles quadrilineatus. SAP11 binds and destabilizes Arabidopsis CINCINNATA (CIN)-related TEOSINTE BRANCHED1, CYCLOIDEA, PROLIFERATING CELL FACTORS 1 and 2 (TCP) transcription factors, which control plant development and promote the expression of lipoxygenase (LOX) genes involved in jasmonate (JA) synthesis. Both the Arabidopsis SAP11 lines and AY-WB-infected plants produce less JA on wounding. Furthermore, the AY-WB insect vector produces more offspring on AY-WB-infected plants, SAP11 transgenic lines, and plants impaired in CIN-TCP and JA synthesis. Thus, SAP11-mediated destabilization of CIN-TCPs leads to the down-regulation of LOX2 expression and JA synthesis and an increase in M. quadrilineatus progeny. Phytoplasmas are obligate inhabitants of their plant host and insect vectors, in which the latter transmits AY-WB to a diverse range of plant species. This finding demonstrates that pathogen effectors can reach beyond the pathogen-host interface to modulate a third organism in the biological interaction.

Host-Feeding Patterns of Culex stigmatosoma (Diptera: Culicidae) in Southern California.

Science.gov (United States)

McPhatter, Lee P; Su, Tianyun; Williams, Greg; Cheng, Min-Lee; Dhillon, Major; Gerry, Alec C

2017-11-07

Knowledge of the blood-feeding patterns exhibited by arthropod vectors is essential for understanding the complex dynamics of vector-borne disease transmission. Some species of mosquitoes belonging to the genus Culex have been implicated as having major roles in the transmission of arboviruses such as West Nile virus, Saint Louis encephalitis virus, and Western equine encephalitis virus. Although the host-feeding patterns for many of these Culex species are well studied, the host-feeding patterns of Culex stigmatosoma Dyar are relatively poorly studied, even though this species is suspected to be an important maintenance vector for West Nile virus and other arboviruses. In the current study, bloodmeals from 976 blood-engorged Cx. stigmatosoma, collected from 30 sites in southern California from 2009-2012, were processed for vertebrate host identification by nucleotide sequencing following polymerase chain reaction to amplify portions of the cytochrome oxidase I and cytochrome b genes of vertebrate animals. Vertebrate DNA was amplified, sequenced, and identified from a total of 647 Cx. stigmatosoma bloodmeals, revealing that 98.6% of bloodmeals were from birds, 1.2% from three mammal species, and a single bloodmeal was from a reptile species. In total, 40 different host species were identified. The greatest number of bloodmeals identified was from domestic chicken (Gallus gallus domesticus L.) (38% of bloodmeals), house sparrow (Passer domesticus L.) (23%), house finch (Haemorhous mexicanus Müller) (17%), American crow (Corvus brachyrhynchos L.) (4%), and mourning dove (Zenaida macroura L.) (3%). However, chicken bloodmeals were identified almost entirely from a single site where mosquito collection devices were placed in the near vicinity of confined domestic chickens. The strongly ornithophilic feeding behavior shown in this study for Cx. stigmatosoma supports the hypothesis that this mosquito species may be an important maintenance (or endemic) vector for

Characterization of a minimal pKW2124 replicon from Weissella cibaria KLC140 and its application for the construction of the Weissella expression vector pKUCm1

Science.gov (United States)

Ku, Hye-Jin; Park, Myeong Soo; Lee, Ju-Hoon

2015-01-01

A 2.1-kb plasmid was previously isolated from Weissella cibaria KLC140 in kimchi and cloned into pUC19 along with the slpA and gfp genes, resulting in an 8.6-kb pKWCSLGFP construct for use as a novel surface display vector. To reduce the size of the vector, the minimal replicon of pKW2124 was determined. The pKW2124 plasmid contains a putative origin of replication (ori), a potential ribosomal binding site (RBS), and the repA gene encoding a plasmid replication protein. To conduct the minimal replicon experiment, four different PCR products (MR1, ori+RBS+repA; MR2, RBS+repA; MR2’, repA; MR3, fragment of repA) were obtained and cloned into pUC19 (pKUCm1, pKUCm2, pKUCm2’, and pKUCm3, respectively) containing the chloramphenicol acetyltransferase (CAT) gene. These constructed vectors were electroporated into W. confusa ATCC 10881 with different transformation efficiencies of 1.5 × 105 CFU/μg, 1.3 × 101 CFU/μg, and no transformation, respectively, suggesting that the putative ori, RBS, and repA gene are essential for optimum plasmid replication. Subsequent segregational plasmid stability testing of pKUCm1 and pKUCm2 showed that the vector pKUCm1 is highly stable up to 100 generations but pKUCm2 was completely lost after 60 generations, suggesting that the putative ori may be important for plasmid stability in the host strain. In addition, a host range test of pKUCm1 revealed that it has a broad host range spectrum including Weissella, Lactococcus, Leuconostoc, and even Lactobacillus. To verify the application of pKUCm1, the β-galactosidase gene and its promoter region from W. cibaria KSD1 were cloned in the vector, resulting in pKUGal. Expression of the β-galactosidase gene was confirmed using blue-white screening after IPTG induction. The small and stable pKUGal vector will be useful for gene transfer, expression, and manipulation in the Weissella genome and in other lactic acid bacteria. PMID:25691882

Spatial variation in host feeding patterns of Culex tarsalis and the Culex pipiens complex (Diptera: Culicidae) in California.

Science.gov (United States)

Thiemann, T C; Lemenager, D A; Kluh, S; Carroll, B D; Lothrop, H D; Reisen, W K

2012-07-01

West Nile virus (family Flaviviridae, genus Flavivirus, WNV) is now endemic in California across a variety of ecological regions that support a wide diversity of potential avian and mammalian host species. Because different avian hosts have varying competence for WNV, determining the blood-feeding patterns of Culex (Diptera: Culicidae) vectors is a key component in understanding the maintenance and amplification of the virus as well as tangential transmission to humans and horses. We investigated the blood-feeding patterns of Culex tarsalis Coquillett and members of the Culex pipiens L. complex from southern to northern California. Nearly 100 different host species were identified from 1,487 bloodmeals, by using the mitochondrial gene cytochrome c oxidase I (COI). Cx. tarsalis fed on a higher diversity of hosts and more frequently on nonhuman mammals than did the Cx. pipiens complex. Several WNV-competent host species, including house finch and house sparrow, were common bloodmeal sources for both vector species across several biomes and could account for WNV maintenance and amplification in these areas. Highly competent American crow, western scrub-jay and yellow-billed magpie also were fed upon often when available and are likely important as amplifying hosts for WNV in some areas. Neither species fed frequently on humans (Cx. pipiens complex [0.4%], Cx. tarsalis [0.2%]), but with high abundance, both species could serve as both enzootic and bridge vectors for WNV.

Herpes simplex virus type 1-derived recombinant and amplicon vectors.

Science.gov (United States)

Fraefel, Cornel; Marconi, Peggy; Epstein, Alberto L

2011-01-01

Herpes simplex virus type 1 (HSV-1) is a human pathogen whose lifestyle is based on a long-term dual interaction with the infected host, being able to establish both lytic and latent infections. The virus genome is a 153 kbp double-stranded DNA molecule encoding more than 80 genes. The interest of HSV-1 as gene transfer vector stems from its ability to infect many different cell types, both quiescent and proliferating cells, the very high packaging capacity of the virus capsid, the outstanding neurotropic adaptations that this virus has evolved, and the fact that it never integrates into the cellular chromosomes, thus avoiding the risk of insertional mutagenesis. Two types of vectors can be derived from HSV-1, recombinant vectors and amplicon vectors, and different methodologies have been developed to prepare large stocks of each type of vector. This chapter summarizes (1) the two approaches most commonly used to prepare recombinant vectors through homologous recombination, either in eukaryotic cells or in bacteria, and (2) the two methodologies currently used to generate helper-free amplicon vectors, either using a bacterial artificial chromosome (BAC)-based approach or a Cre/loxP site-specific recombination strategy.

Comparison Between Several Integrase-defective Lentiviral Vectors Reveals Increased Integration of an HIV Vector Bearing a D167H Mutant

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Muhammad Qamar Saeed

2014-01-01

Full Text Available HIV-1 derived vectors are among the most efficient for gene transduction in mammalian tissues. As the parent virus, they carry out vector genome insertion into the host cell chromatin. Consequently, their preferential integration in transcribed genes raises several conceptual and safety issues. To address part of these questions, HIV-derived vectors have been engineered to be nonintegrating. This was mainly achieved by mutating HIV-1 integrase at functional hotspots of the enzyme enabling the development of streamlined nuclear DNA circles functional for transgene expression. Few integrase mutant vectors have been successfully tested so far for gene transfer. They are cleared with time in mitotic cells, but stable within nondividing retina cells or neurons. Here, we compared six HIV vectors carrying different integrases, either wild type or with different mutations (D64V, D167H, Q168A, K186Q+Q214L+Q216L, and RRK262-264AAH shown to modify integrase enzymatic activity, oligomerization, or interaction with key cellular cofactor of HIV DNA integration as LEDGF/p75 or TNPO3. We show that these mutations differently affect the transduction efficiency as well as rates and patterns of integration of HIV-derived vectors suggesting their different processing in the nucleus. Surprisingly and most interestingly, we report that an integrase carrying the D167H substitution improves vector transduction efficiency and integration in both HEK-293T and primary CD34+ cells.

Efficient gene transfer into nondividing cells by adeno-associated virus-based vectors.

OpenAIRE

Podsakoff, G; Wong, K K; Chatterjee, S

1994-01-01

Gene transfer vectors based on adeno-associated virus (AAV) are emerging as highly promising for use in human gene therapy by virtue of their characteristics of wide host range, high transduction efficiencies, and lack of cytopathogenicity. To better define the biology of AAV-mediated gene transfer, we tested the ability of an AAV vector to efficiently introduce transgenes into nonproliferating cell populations. Cells were induced into a nonproliferative state by treatment with the DNA synthe...

Mechanical Vectors Enhance Fungal Entomopathogen Reduction of the Grasshopper Pest Camnula pellucida (Orthoptera: Acrididae).

Science.gov (United States)

Kistner, Erica J; Saums, Marielle; Belovsky, Gary E

2015-02-01

Mounting scientific evidence indicates that pathogens can regulate insect populations. However, limited dispersal and sensitivity to abiotic conditions often restricts pathogen regulation of host populations. While it is well established that arthropod biological vectors increase pathogen incidence in host populations, few studies have examined whether arthropod mechanical vectors (an organism that transmits pathogens but is not essential to the life cycle of the pathogen) influence host-pathogen dynamics. The importance of mechanical dispersal by ant scavengers, Formica fusca (L.), in a grasshopper-fungal entomopathogen system was investigated. We examined the ability of ants to mechanically disperse and transmit the pathogen, Entomophaga grylli (Fresenius) pathotype 1, to its host, the pest grasshopper Camnula pellucida (Scudder), in a series of laboratory experiments. Fungal spores were dispersed either externally on the ant's body surface or internally through fecal deposition. In addition, a third of all grasshoppers housed with fungal-inoculated ants became infected, indicating that ants can act as mechanical vectors of E. grylli. The effect of ant mechanical vectors on E. grylli incidence was also examined in a field experiment. Ant access to pathogen-exposed experimental grasshopper populations was restricted using organic ant repellent, thereby allowing us to directly compare mechanical and natural transmission. Ants increased grasshopper pathogen mortality by 58%, which led to greater pathogen reductions of grasshopper survival than natural transmission. Taken together, our results indicate that ants enhance E. grylli reduction of grasshopper pest numbers. Therefore, mechanical transmission of pathogens may be an important overlooking component of this grasshopper-fungal pathogen system. © The Author 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Challenges in predicting climate and environmental effects on vector-borne disease episystems in a changing world.

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Tabachnick, W J

2010-03-15

Vector-borne pathogens cause enormous suffering to humans and animals. Many are expanding their range into new areas. Dengue, West Nile and Chikungunya have recently caused substantial human epidemics. Arthropod-borne animal diseases like Bluetongue, Rift Valley fever and African horse sickness pose substantial threats to livestock economies around the world. Climate change can impact the vector-borne disease epidemiology. Changes in climate will influence arthropod vectors, their life cycles and life histories, resulting in changes in both vector and pathogen distribution and changes in the ability of arthropods to transmit pathogens. Climate can affect the way pathogens interact with both the arthropod vector and the human or animal host. Predicting and mitigating the effects of future changes in the environment like climate change on the complex arthropod-pathogen-host epidemiological cycle requires understanding of a variety of complex mechanisms from the molecular to the population level. Although there has been substantial progress on many fronts the challenges to effectively understand and mitigate the impact of potential changes in the environment on vector-borne pathogens are formidable and at an early stage of development. The challenges will be explored using several arthropod-borne pathogen systems as illustration, and potential avenues to meet the challenges will be presented.

Three-dimensional visualisation of developmental stages of an apicomplexan fish blood parasite in its invertebrate host

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Hayes Polly M

2011-11-01

Full Text Available Abstract Background Although widely used in medicine, the application of three-dimensional (3D imaging to parasitology appears limited to date. In this study, developmental stages of a marine fish haemogregarine, Haemogregarina curvata (Apicomplexa: Adeleorina, were investigated in their leech vector, Zeylanicobdella arugamensis; this involved 3D visualisation of brightfield and confocal microscopy images of histological sections through infected leech salivary gland cells. Findings 3D assessment demonstrated the morphology of the haemogregarine stages, their spatial layout, and their relationship with enlarged host cells showing reduced cellular content. Haemogregarine meronts, located marginally within leech salivary gland cells, had small tail-like connections to the host cell limiting membrane; this parasite-host cell interface was not visible in two-dimensional (2D light micrographs and no records of a similar connection in apicomplexan development have been traced. Conclusions This is likely the first account of the use of 3D visualisation to study developmental stages of an apicomplexan parasite in its invertebrate vector. Elucidation of the extent of development of the haemogregarine within the leech salivary cells, together with the unusual connections between meronts and the host cell membrane, illustrates the future potential of 3D visualisation in parasite-vector biology.

Ecotype evolution in Glossina palpalis subspecies, major vectors of sleeping sickness.

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Thierry De Meeûs

2015-03-01

Full Text Available The role of environmental factors in driving adaptive trajectories of living organisms is still being debated. This is even more important to understand when dealing with important neglected diseases and their vectors.In this paper, we analysed genetic divergence, computed from seven microsatellite loci, of 614 tsetse flies (Glossina palpalis gambiensis and Glossina palpalis palpalis, major vectors of animal and human trypanosomes from 28 sites of West and Central Africa. We found that the two subspecies are so divergent that they deserve the species status. Controlling for geographic and time distances that separate these samples, which have a significant effect, we found that G. p. gambiensis from different landscapes (Niayes of Senegal, savannah and coastal environments were significantly genetically different and thus represent different ecotypes or subspecies. We also confirm that G. p. palpalis from Ivory Coast, Cameroon and DRC are strongly divergent.These results provide an opportunity to examine whether new tsetse fly ecotypes might display different behaviour, dispersal patterns, host preferences and vectorial capacities. This work also urges a revision of taxonomic status of Glossina palpalis subspecies and highlights again how fast ecological divergence can be, especially in host-parasite-vector systems.

Lentiviral vectors in cancer immunotherapy.

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Oldham, Robyn Aa; Berinstein, Elliot M; Medin, Jeffrey A

2015-01-01

Basic science advances in cancer immunotherapy have resulted in various treatments that have recently shown success in the clinic. Many of these therapies require the insertion of genes into cells to directly kill them or to redirect the host's cells to induce potent immune responses. Other analogous therapies work by modifying effector cells for improved targeting and enhanced killing of tumor cells. Initial studies done using γ-retroviruses were promising, but safety concerns centered on the potential for insertional mutagenesis have highlighted the desire to develop other options for gene delivery. Lentiviral vectors (LVs) have been identified as potentially more effective and safer alternative delivery vehicles. LVs are now in use in clinical trials for many different types of inherited and acquired disorders, including cancer. This review will discuss current knowledge of LVs and the applications of this viral vector-based delivery vehicle to cancer immunotherapy.

Partitioning the aggregation of parasites on hosts into intrinsic and extrinsic components via an extended Poisson-gamma mixture model.

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Justin M Calabrese

Full Text Available It is well known that parasites are often highly aggregated on their hosts such that relatively few individuals host the large majority of parasites. When the parasites are vectors of infectious disease, a key consequence of this aggregation can be increased disease transmission rates. The cause of this aggregation, however, is much less clear, especially for parasites such as arthropod vectors, which generally spend only a short time on their hosts. Regression-based analyses of ticks on various hosts have focused almost exclusively on identifying the intrinsic host characteristics associated with large burdens, but these efforts have had mixed results; most host traits examined have some small influence, but none are key. An alternative approach, the Poisson-gamma mixture distribution, has often been used to describe aggregated parasite distributions in a range of host/macroparasite systems, but lacks a clear mechanistic basis. Here, we extend this framework by linking it to a general model of parasite accumulation. Then, focusing on blacklegged ticks (Ixodes scapularis on mice (Peromyscus leucopus, we fit the extended model to the best currently available larval tick burden datasets via hierarchical Bayesian methods, and use it to explore the relative contributions of intrinsic and extrinsic factors on observed tick burdens. Our results suggest that simple bad luck-inhabiting a home range with high vector density-may play a much larger role in determining parasite burdens than is currently appreciated.

Unique Safety Issues Associated with Virus Vectored Vaccines: Potential for and Theoretical Consequences of Recombination with Wild Type Virus Strains

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Condit, Richard C.; Williamson, Anna-Lise; Sheets, Rebecca; Seligman, Stephen J.; Monath, Thomas P.; Excler, Jean-Louis; Gurwith, Marc; Bok, Karin; Robertson, James S.; Kim, Denny; Hendry, Michael; Singh, Vidisha; Mac, Lisa M.; Chen, Robert T.

2016-01-01

In 2003 and 2013, the World Health Organization convened informal consultations on characterization and quality aspects of vaccines based on live virus vectors. In the resulting reports, one of several issues raised for future study was the potential for recombination of virus-vectored vaccines with wild type pathogenic virus strains. This paper presents an assessment of this issue formulated by the Brighton Collaboration. To provide an appropriate context for understanding the potential for recombination of virus-vectored vaccines, we review briefly the current status of virus vectored vaccines, mechanisms of recombination between viruses, experience with recombination involving live attenuated vaccines in the field, and concerns raised previously in the literature regarding recombination of virus-vectored vaccines with wild type virus strains. We then present a discussion of the major variables that could influence recombination between a virus-vectored vaccine and circulating wild type virus and the consequences of such recombination, including intrinsic recombination properties of the parent virus used as a vector; sequence relatedness of vector and wild virus; virus host range, pathogenesis and transmission; replication competency of vector in target host; mechanism of vector attenuation; additional factors potentially affecting virulence; and circulation of multiple recombinant vectors in the same target population. Finally, we present some guiding principles for vector design and testing intended to anticipate and mitigate the potential for and consequences of recombination of virus-vectored vaccines with wild type pathogenic virus strains. PMID:27346303

Functional analysis of virion host shutoff protein of pseudorabies virus

International Nuclear Information System (INIS)

Lin, H.-W.; Chang, Y.-Y.; Wong, M.-L.; Lin, J.-W.; Chang, T.-J.

2004-01-01

During lytic infection, the virion host shutoff (vhs) protein of alphaherpesviruses causes the degradation of mRNAs nonspecifically. In this work, we cloned the vhs gene (UL41 open reading frame) of pseudorabies virus (PRV; TNL strain) by PCR, and its nucleotide sequences were determined. The PCR product of vhs gene was subcloned into the prokaryotic pET32b expression vector, and production of the recombinant vhs protein was examined by SDS-PAGE. Result of Western blotting demonstrated that our recombinant vhs protein reacted with antiserum against a synthetic peptide of 17 amino acids of the vhs protein. After purification with nickel-chelate affinity chromatography, the purified recombinant vhs protein exhibited in vitro ribonuclease activity as expected. We further cloned the vhs gene into eukaryotic expression vectors and investigated the intracellular function of vhs protein by DNA transfection. By transient trasfection and CAT assay, we found the CAT activity was reduced in the presence of vhs, indicating that degradation of mRNA of the CAT gene was caused by the vhs. Furthermore, our results showed that the plaque formation of pseudorabies virus was blocked by exogenous vhs. Taken together, we have cloned the vhs gene of pseudorabies virus (TNL strain) and conducted functional analysis of the recombinant vhs protein in vitro as well as in vivo

Andean cutaneous leishmaniasis (Andean-CL, uta) in Peru and Ecuador: the vector Lutzomyia sand flies and reservoir mammals.

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Hashiguchi, Yoshihisa; Gomez L, Eduardo A; Cáceres, Abraham G; Velez, Lenin N; Villegas, Nancy V; Hashiguchi, Kazue; Mimori, Tatsuyuki; Uezato, Hiroshi; Kato, Hirotomo

2018-02-01

The vector Lutzomyia sand flies and reservoir host mammals of the Leishmania parasites, causing the Andean cutaneous leishmaniasis (Andean-CL, uta) in Peru and Ecuador were thoroughly reviewed, performing a survey of literatures including our unpublished data. The Peruvian L. (V.) peruviana, a principal Leishmania species causing Andean-CL in Peru, possessed three Lutzomyia species, Lu. peruensis, Lu. verrucarum and Lu. ayacuchensis as vectors, while the Ecuadorian L. (L.) mexicana parasite possessed only one species Lu. ayacuchensis as the vector. Among these, the Ecuadorian showed a markedly higher rate of natural Leishmania infections. However, the monthly and diurnal biting activities were mostly similar among these vector species was in both countries, and the higher rates of infection (transmission) reported, corresponded to sand fly's higher monthly-activity season (rainy season). The Lu. tejadai sand fly participated as a vector of a hybrid parasite of L. (V.) braziliensis/L. (V.) peruviana in the Peruvian Andes. Dogs were considered to be principal reservoir hosts of the L. (V.) peruviana and L. (L.) mexicana parasites in both countries, followed by other sylvatic mammals such as Phyllotis andium, Didelphis albiventris and Akodon sp. in Peru, and Rattus rattus in Ecuador, but information on the reservoir hosts/mammals was extremely poor in both countries. Thus, the Peruvian disease form demonstrated more complicated transmission dynamics than the Ecuadorian. A brief review was also given to the control of vector and reservoirs in the Andes areas. Such information is crucial for future development of the control strategies of the disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Disruption of Ethylene Responses by Turnip mosaic virus Mediates Suppression of Plant Defense against the Green Peach Aphid Vector.

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Casteel, Clare L; De Alwis, Manori; Bak, Aurélie; Dong, Haili; Whitham, Steven A; Jander, Georg

2015-09-01

Plants employ diverse responses mediated by phytohormones to defend themselves against pathogens and herbivores. Adapted pathogens and herbivores often manipulate these responses to their benefit. Previously, we demonstrated that Turnip mosaic virus (TuMV) infection suppresses callose deposition, an important plant defense induced in response to feeding by its aphid vector, the green peach aphid (Myzus persicae), and increases aphid fecundity compared with uninfected control plants. Further, we determined that production of a single TuMV protein, Nuclear Inclusion a-Protease (NIa-Pro) domain, was responsible for changes in host plant physiology and increased green peach aphid reproduction. To characterize the underlying molecular mechanisms of this phenomenon, we examined the role of three phytohormone signaling pathways, jasmonic acid, salicylic acid, and ethylene (ET), in TuMV-infected Arabidopsis (Arabidopsis thaliana), with or without aphid herbivory. Experiments with Arabidopsis mutants ethylene insensitive2 and ethylene response1, and chemical inhibitors of ET synthesis and perception (aminoethoxyvinyl-glycine and 1-methylcyclopropene, respectively), show that the ET signaling pathway is required for TuMV-mediated suppression of Arabidopsis resistance to the green peach aphid. Additionally, transgenic expression of NIa-Pro in Arabidopsis alters ET responses and suppresses aphid-induced callose formation in an ET-dependent manner. Thus, disruption of ET responses in plants is an additional function of NIa-Pro, a highly conserved potyvirus protein. Virus-induced changes in ET responses may mediate vector-plant interactions more broadly and thus represent a conserved mechanism for increasing transmission by insect vectors across generations. © 2015 American Society of Plant Biologists. All Rights Reserved.

Nesting Bird “Host Funnel” Increases Mosquito-Bird Contact Rate

OpenAIRE

CAILLOUËT, KEVIN A.; RIGGAN, ANNA E.; BULLUCK, LESLEY P.; CARLSON, JOHN C.; SABO, ROY T.

2013-01-01

Increases in vector-host contact rates can enhance arbovirus transmission intensity. We investigated weekly fluctuations in contact rates between mosquitoes and nesting birds using the recently described Nest Mosquito Trap (NMT). The number of mosquitoes per nestling increased from < 1 mosquito per trap night to 36.2 in the final 2 wk of the nesting season. Our evidence suggests the coincidence of the end of the avian nesting season and increasing mosquito abundances may have caused a “host f...

The geographical vector in distribution of genetic diversity for Clonorchis sinensis.

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Solodovnik, Daria A; Tatonova, Yulia V; Burkovskaya, Polina V

2018-01-01

Clonorchis sinensis, the causative agent of clonorchiasis, is one of the most important parasites that inhabit countries of East and Southeast Asia. In this study, we validated the existence of a geographical vector for C. sinensis using the partial cox1 mtDNA gene, which includes a conserved region. The samples of parasite were divided into groups corresponding to three river basins, and the size of the conserved region had a strong tendency to increase from the northernmost to the southernmost samples. This indicates the availability of the geographical vector in distribution of genetic diversity. A vector is a quantity that is characterized by magnitude and direction. Geographical vector obtained in cox1 gene of C. sinensis has both these features. The reasons for the occurrence of this feature, including the influence of intermediate and definitive hosts on vector formation, and the possibility of its use for clonorchiasis monitoring are discussed. Graphical abstract ᅟ.

Effects of sublethal exposure to boric acid sugar bait on adult survival, host-seeking, bloodfeeding behavior, and reproduction of Stegomyia albopicta.

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Ali, Arshad; Xue, Rui-De; Barnard, Donald R

2006-09-01

Effects of sublethal exposure to 0.1% boric acid sugar bait on adult survival, host-seeking, bloodfeeding behavior, and reproduction of Stegomyia albopicta were studied in the laboratory. Survival of males as well as females was significantly reduced when exposed to the bait, compared to control adults. The host-seeking and bloodfeeding activities in the baited females decreased, but the mean duration of blood engorgement (probing to voluntary withdrawal of proboscis) was not significantly different between the baited and control females. The landing and biting rates (human forearm) were significantly reduced in the baited females compared to nonbaited controls. Fecundity and fertility (based on number of laid eggs per female and percentage egg hatch, respectively) in the baited females were significantly reduced, and ovarian development was retarded. Sublethal exposure to sugar-based boric acid bait has the potential to reduce adult populations of St. albopicta.

Integrated malaria vector control in different agro-ecosystems in western Kenya

NARCIS (Netherlands)

Imbahale, S.S.

2009-01-01

Malaria is a complex disease and its transmission is a function of the interaction between the Anopheles mosquito vector, the Plasmodium parasite, the hosts and the environment. Malaria control has mainly targeted the Plasmodium parasite or the adult anopheline mosquitoes. However, development of

A novel prokaryotic vector for identification and selection of recombinants: Direct use of the vector for expression studies in E. coli

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Apte-Deshpande Anjali

2010-05-01

Full Text Available Abstract Background The selection of bacterial recombinants that harbour a desired insert, has been a key factor in molecular cloning and a series of screening procedures need to be performed for selection of clones carrying the genes of interest. The conventional cloning techniques are reported to have problems such as screening high number of colonies, generation of false positives, setting up of control ligation mix with vector alone etc. Results We describe the development of a novel dual cloning/expression vector, which enables to screen the recombinants directly and expression of the gene of interest. The vector contains Green fluorescence protein (GFP as the reporter gene and is constructed in such a way that the E. coli cells upon transformation with this vector does not show any fluorescence, but readily fluoresce upon insertion of a foreign gene of interest. The same construct could be easily used for screening of the clones and expression studies by mere switching to specific hosts. Conclusions This is the first vector reported that takes the property of colour or fluorescence to be achieved only upon cloning while all the other vectors available commercially show loss of colour or loss of fluorescence upon cloning. As the fluorescence of GFP depends on the solubility of the protein, the intensity of the fluorescence would also indicate the extent of solubility of the expressed target protein.

Roles of d-Amino Acids on the Bioactivity of Host Defense Peptides

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Hao Li

2016-06-01

Full Text Available Host defense peptides (HDPs are positively-charged and amphipathic components of the innate immune system that have demonstrated great potential to become the next generation of broad spectrum therapeutic agents effective against a vast array of pathogens and tumor. As such, many approaches have been taken to improve the therapeutic efficacy of HDPs. Amongst these methods, the incorporation of d-amino acids (d-AA is an approach that has demonstrated consistent success in improving HDPs. Although, virtually all HDP review articles briefly mentioned about the role of d-AA, however it is rather surprising that no systematic review specifically dedicated to this topic exists. Given the impact that d-AA incorporation has on HDPs, this review aims to fill that void with a systematic discussion of the impact of d-AA on HDPs.

Global Positioning Systems (GPS) Technology to Study Vector-Pathogen-Host Interactions

Science.gov (United States)

2012-10-26

OG, et al. (2009) Spatial evaluation and modeling of Dengue seroprevalence and vector density in Rio de Janeiro , Brazil. PLoS Negl Trop Dis 3: e545. 38...haemorrhagic fever. Bull World Health Organ 44: 651–657. 34. De Benedictis J, Chow-Shaffer E, Costero A, Clark GG, Edman JD, et al. (2003) Identification of the...shaded area is the Nai Mueang Subdistrict, and the Ping River is depicted in light blue. Tropical Medicine and International Health volume 17 no 9 pp 1076

Red-shifted fluorescent proteins mPlum and mRaspberry and polynucleotides encoding the same

Science.gov (United States)

Tsien, Roger Y [La Jolla, CA; Wang, Lei [San Diego, CA

2008-07-01

Methods using somatic hypermutation (SHM) for producing polypeptide and nucleic acid variants, and nucleic acids encoding such polypeptide variants are disclosed. Such variants may have desired properties. Also disclosed are novel polypeptides, such as improved fluorescent proteins, produced by the novel methods, and nucleic acids, vectors, and host cells comprising such vectors.

Methods for engineering polypeptide variants via somatic hypermutation and polypeptide made thereby

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Tsien, Roger Y; Wang, Lei

2015-01-13

Methods using somatic hypermutation (SHM) for producing polypeptide and nucleic acid variants, and nucleic acids encoding such polypeptide variants are disclosed. Such variants may have desired properties. Also disclosed are novel polypeptides, such as improved fluorescent proteins, produced by the novel methods, and nucleic acids, vectors, and host cells comprising such vectors.

Potent and reversible lentiviral vector restriction in murine induced pluripotent stem cells.

Science.gov (United States)

Geis, Franziska K; Galla, Melanie; Hoffmann, Dirk; Kuehle, Johannes; Zychlinski, Daniela; Maetzig, Tobias; Schott, Juliane W; Schwarzer, Adrian; Goffinet, Christine; Goff, Stephen P; Schambach, Axel

2017-05-31

Retroviral vectors are derived from wild-type retroviruses, can be used to study retrovirus-host interactions and are effective tools in gene and cell therapy. However, numerous cell types are resistant or less permissive to retrovirus infection due to the presence of active defense mechanisms, or the absence of important cellular host co-factors. In contrast to multipotent stem cells, pluripotent stem cells (PSC) have potential to differentiate into all three germ layers. Much remains to be elucidated in the field of anti-viral immunity in stem cells, especially in PSC. In this study, we report that transduction with HIV-1-based, lentiviral vectors (LV) is impaired in murine PSC. Analyses of early retroviral events in induced pluripotent stem cells (iPSC) revealed that the restriction is independent of envelope choice and does not affect reverse transcription, but perturbs nuclear entry and proviral integration. Proteasomal inhibition by MG132 could not circumvent the restriction. However, prevention of cyclophilin A (CypA) binding to the HIV-1 capsid via use of either a CypA inhibitor (cyclosporine A) or CypA-independent capsid mutants improved transduction. In addition, application of higher vector doses also increased transduction. Our data revealed a CypA mediated restriction in iPSC, which was acquired during reprogramming, associated with pluripotency and relieved upon subsequent differentiation. We showed that murine PSC and iPSC are less susceptible to LV. The block observed in iPSC was CypA-dependent and resulted in reduced nuclear entry of viral DNA and proviral integration. Our study helps to improve transduction of murine pluripotent cells with HIV-1-based vectors and contributes to our understanding of retrovirus-host interactions in PSC.

Prolonged Integration Site Selection of a Lentiviral Vector in the Genome of Human Keratinocytes.

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Qian, Wei; Wang, Yong; Li, Rui-Fu; Zhou, Xin; Liu, Jing; Peng, Dai-Zhi

2017-03-03

BACKGROUND Lentiviral vectors have been successfully used for human skin cell gene transfer studies. Defining the selection of integration sites for retroviral vectors in the host genome is crucial in risk assessment analysis of gene therapy. However, genome-wide analyses of lentiviral integration sites in human keratinocytes, especially after prolonged growth, are poorly understood. MATERIAL AND METHODS In this study, 874 unique lentiviral vector integration sites in human HaCaT keratinocytes after long-term culture were identified and analyzed with the online tool GTSG-QuickMap and SPSS software. RESULTS The data indicated that lentiviral vectors showed integration site preferences for genes and gene-rich regions. CONCLUSIONS This study will likely assist in determining the relative risks of the lentiviral vector system and in the design of a safe lentiviral vector system in the gene therapy of skin diseases.

Codivergence of mycoviruses with their hosts.

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Markus Göker

Full Text Available BACKGROUND: The associations between pathogens and their hosts are complex and can result from any combination of evolutionary events such as codivergence, switching, and duplication of the pathogen. Mycoviruses are RNA viruses which infect fungi and for which natural vectors are so far unknown. Thus, lateral transfer might be improbable and codivergence their dominant mode of evolution. Accordingly, mycoviruses are a suitable target for statistical tests of virus-host codivergence, but inference of mycovirus phylogenies might be difficult because of low sequence similarity even within families. METHODOLOGY: We analyzed here the evolutionary dynamics of all mycovirus families by comparing virus and host phylogenies. Additionally, we assessed the sensitivity of the co-phylogenetic tests to the settings for inferring virus trees from their genome sequences and approximate, taxonomy-based host trees. CONCLUSIONS: While sequence alignment filtering modes affected branch support, the overall results of the co-phylogenetic tests were significantly influenced only by the number of viruses sampled per family. The trees of the two largest families, Partitiviridae and Totiviridae, were significantly more similar to those of their hosts than expected by chance, and most individual host-virus links had a significant positive impact on the global fit, indicating that codivergence is the dominant mode of virus diversification. However, in this regard mycoviruses did not differ from closely related viruses sampled from non-fungus hosts. The remaining virus families were either dominated by other evolutionary modes or lacked an apparent overall pattern. As this negative result might be caused by insufficient taxon sampling, the most parsimonious hypothesis still is that host-parasite evolution is basically the same in all mycovirus families. This is the first study of mycovirus-host codivergence, and the results shed light not only on how mycovirus biology

Visual and olfactory associative learning in the malaria vector Anopheles gambiae sensu stricto

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Chilaka Nora

2012-01-01

Full Text Available Abstract Background Memory and learning are critical aspects of the ecology of insect vectors of human pathogens because of their potential effects on contacts between vectors and their hosts. Despite this epidemiological importance, there have been only a limited number of studies investigating associative learning in insect vector species and none on Anopheline mosquitoes. Methods A simple behavioural assays was developed to study visual and olfactory associative learning in Anopheles gambiae, the main vector of malaria in Africa. Two contrasted membrane qualities or levels of blood palatability were used as reinforcing stimuli for bi-directional conditioning during blood feeding. Results Under such experimental conditions An. gambiae females learned very rapidly to associate visual (chequered and white patterns and olfactory cues (presence and absence of cheese or Citronella smell with the reinforcing stimuli (bloodmeal quality and remembered the association for up to three days. Associative learning significantly increased with the strength of the conditioning stimuli used. Importantly, learning sometimes occurred faster when a positive reinforcing stimulus (palatable blood was associated with an innately preferred cue (such as a darker visual pattern. However, the use of too attractive a cue (e.g. Shropshire cheese smell was counter-productive and decreased learning success. Conclusions The results address an important knowledge gap in mosquito ecology and emphasize the role of associative memory for An. gambiae's host finding and blood-feeding behaviour with important potential implications for vector control.

Host and environmental factors influencing "Candidatus Liberibacter asiaticus" acquisition in Diaphorina citri.

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Wu, Fengnian; Huang, Jiaquan; Xu, Meirong; Fox, Eduardo G P; Beattie, G Andrew C; Holford, Paul; Cen, Yijing; Deng, Xiaoling

2018-05-03

Diaphorina citri is a vector of "Candidatus Liberibacter asiaticus" (CLas) associated with citrus Huanglongbing. In this study, the infection and titers of CLas in the psyllid, were monitored for life cycle stage, sex, host-plant CLas titer, host-plant genotype, and ambient temperature. Acquisition efficiency of CLas by D. citri was highest in nymphs reared at 25 °C on a host plant with high CLas titers but was independent of the host genotypes assessed and of vector sex. We further observed that D. citri nymphs acquired CLas more rapidly than adults based on acquisition access periods (AAPs). CLas did not multiply in the alimentary canal, hemolymph, and salivary glands of adults for 18 d after a 3-day AAP as adult. However, CLas multiplication was detected in hemolymph and salivary gland of adults after the bacterium was acquired by nymphs. Eighty percent of salivary glands of adults contained CLas 18 d after a 3-day AAP as nymph compared to 10% 18 d after a 3-day AAP as adults. Different factors tested herein influenced CLas acquisition efficiency of D. citri, CLas multiplication and spread inside the psyllid. These observations serve to better understand mechanisms of CLas infection in D. citri. This article is protected by copyright. All rights reserved.

Effects of the deletion of early region 4 (E4 open reading frame 1 (orf1, orf1-2, orf1-3 and orf1-4 on virus-host cell interaction, transgene expression, and immunogenicity of replicating adenovirus HIV vaccine vectors.

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Michael A Thomas

Full Text Available The global health burden engendered by human immunodeficiency virus (HIV-induced acquired immunodeficiency syndrome (AIDS is a sobering reminder of the pressing need for a preventative vaccine. In non-human primate models replicating adenovirus (Ad-HIV/SIV recombinant vaccine vectors have been shown to stimulate potent immune responses culminating in protection against challenge exposures. Nonetheless, an increase in the transgene carrying capacity of these Ad vectors, currently limited to approximately 3000 base pairs, would greatly enhance their utility. Using a replicating, E3-deleted Ad type 5 host range mutant (Ad5 hr encoding full-length single-chain HIVBaLgp120 linked to the D1 and D2 domains of rhesus macaque CD4 (rhFLSC we systematically deleted the genes encoding early region 4 open reading frame 1 (E4orf1 through E4orf4. All the Ad-rhFLSC vectors produced similar levels of viral progeny. Cell cycle analysis of infected human and monkey cells revealed no differences in virus-host interaction. The parental and E4-deleted viruses expressed comparable levels of the transgene with kinetics similar to Ad late proteins. Similar levels of cellular immune responses and transgene-specific antibodies were elicited in vaccinated mice. However, differences in recognition of Ad proteins and induced antibody subtypes were observed, suggesting that the E4 gene products might modulate antibody responses by as yet unknown mechanisms. In short, we have improved the transgene carrying capacity by one thousand base pairs while preserving the replicability, levels of transgene expression, and immunogenicity critical to these vaccine vectors. This additional space allows for flexibility in vaccine design that could not be obtained with the current vector and as such should facilitate the goal of improving vaccine efficacy. To the best of our knowledge, this is the first report describing the effects of these E4 deletions on transgene expression and

Effects of the deletion of early region 4 (E4) open reading frame 1 (orf1), orf1-2, orf1-3 and orf1-4 on virus-host cell interaction, transgene expression, and immunogenicity of replicating adenovirus HIV vaccine vectors.

Science.gov (United States)

Thomas, Michael A; Song, Rui; Demberg, Thorsten; Vargas-Inchaustegui, Diego A; Venzon, David; Robert-Guroff, Marjorie

2013-01-01

The global health burden engendered by human immunodeficiency virus (HIV)-induced acquired immunodeficiency syndrome (AIDS) is a sobering reminder of the pressing need for a preventative vaccine. In non-human primate models replicating adenovirus (Ad)-HIV/SIV recombinant vaccine vectors have been shown to stimulate potent immune responses culminating in protection against challenge exposures. Nonetheless, an increase in the transgene carrying capacity of these Ad vectors, currently limited to approximately 3000 base pairs, would greatly enhance their utility. Using a replicating, E3-deleted Ad type 5 host range mutant (Ad5 hr) encoding full-length single-chain HIVBaLgp120 linked to the D1 and D2 domains of rhesus macaque CD4 (rhFLSC) we systematically deleted the genes encoding early region 4 open reading frame 1 (E4orf1) through E4orf4. All the Ad-rhFLSC vectors produced similar levels of viral progeny. Cell cycle analysis of infected human and monkey cells revealed no differences in virus-host interaction. The parental and E4-deleted viruses expressed comparable levels of the transgene with kinetics similar to Ad late proteins. Similar levels of cellular immune responses and transgene-specific antibodies were elicited in vaccinated mice. However, differences in recognition of Ad proteins and induced antibody subtypes were observed, suggesting that the E4 gene products might modulate antibody responses by as yet unknown mechanisms. In short, we have improved the transgene carrying capacity by one thousand base pairs while preserving the replicability, levels of transgene expression, and immunogenicity critical to these vaccine vectors. This additional space allows for flexibility in vaccine design that could not be obtained with the current vector and as such should facilitate the goal of improving vaccine efficacy. To the best of our knowledge, this is the first report describing the effects of these E4 deletions on transgene expression and immunogenicity in a

Chagas disease vector blood meal sources identified by protein mass spectrometry.

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Judith I Keller

Full Text Available Chagas disease is a complex vector borne parasitic disease involving blood feeding Triatominae (Hemiptera: Reduviidae insects, also known as kissing bugs, and the vertebrates they feed on. This disease has tremendous impacts on millions of people and is a global health problem. The etiological agent of Chagas disease, Trypanosoma cruzi (Kinetoplastea: Trypanosomatida: Trypanosomatidae, is deposited on the mammalian host in the insect's feces during a blood meal, and enters the host's blood stream through mucous membranes or a break in the skin. Identifying the blood meal sources of triatomine vectors is critical in understanding Chagas disease transmission dynamics, can lead to identification of other vertebrates important in the transmission cycle, and aids management decisions. The latter is particularly important as there is little in the way of effective therapeutics for Chagas disease. Several techniques, mostly DNA-based, are available for blood meal identification. However, further methods are needed, particularly when sample conditions lead to low-quality DNA or to assess the risk of human cross-contamination. We demonstrate a proteomics-based approach, using liquid chromatography tandem mass spectrometry (LC-MS/MS to identify host-specific hemoglobin peptides for blood meal identification in mouse blood control samples and apply LC-MS/MS for the first time to Triatoma dimidiata insect vectors, tracing blood sources to species. In contrast to most proteins, hemoglobin, stabilized by iron, is incredibly stable even being preserved through geologic time. We compared blood stored with and without an anticoagulant and examined field-collected insect specimens stored in suboptimal conditions such as at room temperature for long periods of time. To our knowledge, this is the first study using LC-MS/MS on field-collected arthropod disease vectors to identify blood meal composition, and where blood meal identification was confirmed with more

A Review of Methods for Detection of Hepatozoon Infection in Carnivores and Arthropod Vectors.

Science.gov (United States)

Modrý, David; Beck, Relja; Hrazdilová, Kristýna; Baneth, Gad

2017-01-01

Vector-borne protists of the genus Hepatozoon belong to the apicomplexan suborder Adeleorina. The taxonomy of Hepatozoon is unsettled and different phylogenetic clades probably represent evolutionary units deserving the status of separate genera. Throughout our review, we focus on the monophyletic assemblage of Hepatozoon spp. from carnivores, classified as Hepatozoon sensu stricto that includes important pathogens of domestic and free-ranging canine and feline hosts. We provide an overview of diagnostic methods and approaches from classical detection in biological materials, through serological tests to nucleic acid amplification tests (NAATs). Critical review of used primers for the 18S rDNA is provided, together with information on individual primer pairs. Extension of used NAATs target to cover also mitochondrial genes is suggested as a key step in understanding the diversity and molecular epidemiology of Hepatozoon infections in mammals.

Primary blood-hosts of mosquitoes are influenced by social and ecological conditions in a complex urban landscape.

Science.gov (United States)

Goodman, Heather; Egizi, Andrea; Fonseca, Dina M; Leisnham, Paul T; LaDeau, Shannon L

2018-04-10

Temperate urban landscapes support persistent and growing populations of Culex and Aedes mosquito vectors. Large urban mosquito populations can represent a significant risk for transmission of emergent arboviral infection. However, even large mosquito populations are only a risk to the animals they bite. The purpose of this study is to identify and assess spatial patterns of host-use in a temperate urban landscape with heterogeneous socio-economic and ecological conditions. Mosquito blood meals were collected from neighborhoods categorized along a socio-economic gradient in Baltimore, MD, USA. Blood meal hosts were identified for two Aedes (Ae. albopictus and Ae. japonicus) and three Culex (Cx. pipiens, Cx. restuans and Cx. salinarius) species. The brown rat (Rattus norvegicus) was the most frequently detected host in both Aedes species and Cx. salinarius. Human biting was evident in Aedes and Culex species and the proportion of human blood meals from Ae. albopictus varied significantly with neighborhood socio-economic status. Aedes albopictus was most likely to feed on human blood hosts (at 50%) in residential blocks categorized as having income above the city median, although there were still more total human bites detected from lower income blocks where Ae. albopictus was more abundant. Birds were the most frequently detected Culex blood hosts but were absent from all Aedes sampled. This study highlights fine-scale variation in host-use by medically important mosquito vectors and specifically investigates blood meal composition at spatial scales relevant to urban mosquito dispersal and human exposure. Further, the work emphasizes the importance of neighborhood economics and infrastructure management in shaping both the relative abundance of vectors and local blood feeding strategies. The invasive brown rat was an important blood source across vector species and neighborhoods in Baltimore. We show that social and economic conditions can be important predictors of

A spatial model of mosquito host-seeking behavior.

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Bree Cummins

Full Text Available Mosquito host-seeking behavior and heterogeneity in host distribution are important factors in predicting the transmission dynamics of mosquito-borne infections such as dengue fever, malaria, chikungunya, and West Nile virus. We develop and analyze a new mathematical model to describe the effect of spatial heterogeneity on the contact rate between mosquito vectors and hosts. The model includes odor plumes generated by spatially distributed hosts, wind velocity, and mosquito behavior based on both the prevailing wind and the odor plume. On a spatial scale of meters and a time scale of minutes, we compare the effectiveness of different plume-finding and plume-tracking strategies that mosquitoes could use to locate a host. The results show that two different models of chemotaxis are capable of producing comparable results given appropriate parameter choices and that host finding is optimized by a strategy of flying across the wind until the odor plume is intercepted. We also assess the impact of changing the level of host aggregation on mosquito host-finding success near the end of the host-seeking flight. When clusters of hosts are more tightly associated on smaller patches, the odor plume is narrower and the biting rate per host is decreased. For two host groups of unequal number but equal spatial density, the biting rate per host is lower in the group with more individuals, indicative of an attack abatement effect of host aggregation. We discuss how this approach could assist parameter choices in compartmental models that do not explicitly model the spatial arrangement of individuals and how the model could address larger spatial scales and other probability models for mosquito behavior, such as Lévy distributions.

Host choice and human blood index of Anopheles pseudopunctipennis in a village of the Andean valleys of Bolivia

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Bouchité Bernard

2007-01-01

Full Text Available Abstract Background The Human Blood Index (HBI, proportion of bloodmeals of a mosquito population obtained from man is relevant to epidemiological assessment and to the modification of measures to interrupt malaria transmission since the vectorial capacity of the vector varies as the square of the HBI. Anopheles pseudopunctipennis is a main malaria vector in South America. Unfortunately, few data exist concerning HBI values in its range of distribution and none from Bolivia where this species is considered as an important malaria vector in the central Andes. Methods The host choice of An. pseudopunctipennis has been studied in Mataral, a characteristic village of the central Andes of Bolivia. Mosquito host feeding preference experiments (equal accessibility to host in homogenous environment were monitored using baited mosquito nets in latin square designs. Host feeding selection experiments (natural feeding pattern in heterogeneous environment was measured by bloodmeal analysis, using ELISA to determine the origin of blood. Mosquito bloodmeals were collected on various occasions, using various techniques in a variety of sampling sites. A survey of the possible blood sources has also been carried out in the village. Data were analysed with the forage ratio method. Results An. pseudopunctipennis chooses amongst hosts. Sheep, goats, donkeys and humans are the preferred hosts, while dogs, pigs and chicken are rarely bitten. An. pseudopunctipennis has an opportunistic behaviour, in particular within the preferred hosts. The HBI in Mataral is ≈40% and in the central Andes, may range from 30–50%, in accordance to other findings. A high proportion of mixed meals were encountered (8%, and cryptic meals are likely more numerous. There was no difference amongst the HBI from parous and nulliparous mosquitoes. Conclusion Forage ratio analysis is a powerful tool to interpret mosquito host choices. However, refinements in sampling strategies are still

Widespread plant specialization in the polyphagous planthopper Hyalesthes obsoletus (Cixiidae), a major vector of stolbur phytoplasma: Evidence of cryptic speciation.

Science.gov (United States)

Kosovac, Andrea; Johannesen, Jes; Krstić, Oliver; Mitrović, Milana; Cvrković, Tatjana; Toševski, Ivo; Jović, Jelena

2018-01-01

The stolbur phytoplasma vector Hyalesthes obsoletus is generally considered as a polyphagous species associated with numerous wild and cultivated plants. However, recent research in southeastern Europe, the distribution centre of H. obsoletus and the area of most stolbur-inflicted crop diseases, points toward specific host-plant associations of the vector, indicating specific vector-based transmission routes. Here, we study the specificity of populations associated with four host-plants using mitochondrial and nuclear genetic markers, and we evaluate the evolution of host-shifts in H. obsoletus. Host-plant use was confirmed for Convolvulus arvensis, Urtica dioica, Vitex agnus-castus and Crepis foetida. Mitochondrial genetic analysis showed sympatric occurrence of three phylogenetic lineages that were ecologically delineated by host-plant preference, but were morphologically inseparable. Nuclear data supported the existence of three genetic groups (Evanno's ΔK(3) = 803.72) with average genetic membership probabilities > 90%. While populations associated with C. arvensis and U. dioica form a homogenous group, populations affiliated with V. agnus-castus and C. foetida constitute two independent plant-associated lineages. The geographical signal permeating the surveyed populations indicated complex diversification processes associated with host-plant selection and likely derived from post-glacial refugia in the eastern Mediterranean. This study provides evidence for cryptic species diversification within H. obsoletus sensu lato: i) consistent mitochondrial differentiation (1.1-1.5%) among host-associated populations in syntopy and in geographically distant areas, ii) nuclear genetic variance supporting mitochondrial data, and iii) average mitochondrial genetic distances among host-associated meta-populations are comparable to the most closely related, morphologically distinguishable species, i.e., Hyalesthes thracicus (2.1-3.3%).

Widespread plant specialization in the polyphagous planthopper Hyalesthes obsoletus (Cixiidae, a major vector of stolbur phytoplasma: Evidence of cryptic speciation.

Directory of Open Access Journals (Sweden)

Andrea Kosovac

Full Text Available The stolbur phytoplasma vector Hyalesthes obsoletus is generally considered as a polyphagous species associated with numerous wild and cultivated plants. However, recent research in southeastern Europe, the distribution centre of H. obsoletus and the area of most stolbur-inflicted crop diseases, points toward specific host-plant associations of the vector, indicating specific vector-based transmission routes. Here, we study the specificity of populations associated with four host-plants using mitochondrial and nuclear genetic markers, and we evaluate the evolution of host-shifts in H. obsoletus. Host-plant use was confirmed for Convolvulus arvensis, Urtica dioica, Vitex agnus-castus and Crepis foetida. Mitochondrial genetic analysis showed sympatric occurrence of three phylogenetic lineages that were ecologically delineated by host-plant preference, but were morphologically inseparable. Nuclear data supported the existence of three genetic groups (Evanno's ΔK(3 = 803.72 with average genetic membership probabilities > 90%. While populations associated with C. arvensis and U. dioica form a homogenous group, populations affiliated with V. agnus-castus and C. foetida constitute two independent plant-associated lineages. The geographical signal permeating the surveyed populations indicated complex diversification processes associated with host-plant selection and likely derived from post-glacial refugia in the eastern Mediterranean. This study provides evidence for cryptic species diversification within H. obsoletus sensu lato: i consistent mitochondrial differentiation (1.1-1.5% among host-associated populations in syntopy and in geographically distant areas, ii nuclear genetic variance supporting mitochondrial data, and iii average mitochondrial genetic distances among host-associated meta-populations are comparable to the most closely related, morphologically distinguishable species, i.e., Hyalesthes thracicus (2.1-3.3%.

Widespread plant specialization in the polyphagous planthopper Hyalesthes obsoletus (Cixiidae), a major vector of stolbur phytoplasma: Evidence of cryptic speciation

Science.gov (United States)

Kosovac, Andrea; Johannesen, Jes; Krstić, Oliver; Cvrković, Tatjana; Toševski, Ivo

2018-01-01

The stolbur phytoplasma vector Hyalesthes obsoletus is generally considered as a polyphagous species associated with numerous wild and cultivated plants. However, recent research in southeastern Europe, the distribution centre of H. obsoletus and the area of most stolbur-inflicted crop diseases, points toward specific host-plant associations of the vector, indicating specific vector-based transmission routes. Here, we study the specificity of populations associated with four host-plants using mitochondrial and nuclear genetic markers, and we evaluate the evolution of host-shifts in H. obsoletus. Host-plant use was confirmed for Convolvulus arvensis, Urtica dioica, Vitex agnus-castus and Crepis foetida. Mitochondrial genetic analysis showed sympatric occurrence of three phylogenetic lineages that were ecologically delineated by host-plant preference, but were morphologically inseparable. Nuclear data supported the existence of three genetic groups (Evanno’s ΔK(3) = 803.72) with average genetic membership probabilities > 90%. While populations associated with C. arvensis and U. dioica form a homogenous group, populations affiliated with V. agnus-castus and C. foetida constitute two independent plant-associated lineages. The geographical signal permeating the surveyed populations indicated complex diversification processes associated with host-plant selection and likely derived from post-glacial refugia in the eastern Mediterranean. This study provides evidence for cryptic species diversification within H. obsoletus sensu lato: i) consistent mitochondrial differentiation (1.1–1.5%) among host-associated populations in syntopy and in geographically distant areas, ii) nuclear genetic variance supporting mitochondrial data, and iii) average mitochondrial genetic distances among host-associated meta-populations are comparable to the most closely related, morphologically distinguishable species, i.e., Hyalesthes thracicus (2.1–3.3%). PMID:29738577

Retroviral Vectors for Analysis of Viral Mutagenesis and Recombination

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Jonathan M.O. Rawson

2014-09-01

Full Text Available Retrovirus population diversity within infected hosts is commonly high due in part to elevated rates of replication, mutation, and recombination. This high genetic diversity often complicates the development of effective diagnostics, vaccines, and antiviral drugs. This review highlights the diverse vectors and approaches that have been used to examine mutation and recombination in retroviruses. Retroviral vectors for these purposes can broadly be divided into two categories: those that utilize reporter genes as mutation or recombination targets and those that utilize viral genes as targets of mutation or recombination. Reporter gene vectors greatly facilitate the detection, quantification, and characterization of mutants and/or recombinants, but may not fully recapitulate the patterns of mutagenesis or recombination observed in native viral gene sequences. In contrast, the detection of mutations or recombination events directly in viral genes is more biologically relevant but also typically more challenging and inefficient. We will highlight the advantages and disadvantages of the various vectors and approaches used as well as propose ways in which they could be improved.

Atomic evidence that modification of H-bonds established with amino acids critical for host-cell binding induces sterile immunity against malaria

Energy Technology Data Exchange (ETDEWEB)

Patarroyo, Manuel E., E-mail: mepatarr@mail.com [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia); Universidad Nacional de Colombia, Bogota (Colombia); Cifuentes, Gladys [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia); Universidad del Rosario, Bogota (Colombia); Pirajan, Camilo; Moreno-Vranich, Armando [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia); Vanegas, Magnolia [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia); Universidad Nacional de Colombia, Bogota (Colombia); Universidad del Rosario, Bogota (Colombia)

2010-04-09

Based on the 3D X-ray crystallographic structures of relevant proteins of the malaria parasite involved in invasion to host cells and 3D NMR structures of High Activity Binding Peptides (HABPs) and their respective analogues, it was found that HABPs are rendered into highly immunogenic and sterile immunity inducers in the Aotus experimental model by modifying those amino acids that establish H-bonds with other HABPs or binding to host's cells. This finding adds striking and novel physicochemical principles, at the atomic level, for a logical and rational vaccine development methodology against infectious disease, among them malaria.

Atomic evidence that modification of H-bonds established with amino acids critical for host-cell binding induces sterile immunity against malaria

International Nuclear Information System (INIS)

Patarroyo, Manuel E.; Cifuentes, Gladys; Pirajan, Camilo; Moreno-Vranich, Armando; Vanegas, Magnolia

2010-01-01

Based on the 3D X-ray crystallographic structures of relevant proteins of the malaria parasite involved in invasion to host cells and 3D NMR structures of High Activity Binding Peptides (HABPs) and their respective analogues, it was found that HABPs are rendered into highly immunogenic and sterile immunity inducers in the Aotus experimental model by modifying those amino acids that establish H-bonds with other HABPs or binding to host's cells. This finding adds striking and novel physicochemical principles, at the atomic level, for a logical and rational vaccine development methodology against infectious disease, among them malaria.

[New strategy for RNA vectorization in mammalian cells. Use of a peptide vector].

Science.gov (United States)

Vidal, P; Morris, M C; Chaloin, L; Heitz, F; Divita, G

1997-04-01

A major barrier for gene delivery is the low permeability of nucleic acids to cellular membranes. The development of antisenses and gene therapy has focused mainly on improving methods of oligonucleotide or gene delivery to the cell. In this report we described a new strategy for RNA cell delivery, based on a short single peptide. This peptide vector is derived from both the fusion domain of the gp41 protein of HIV and the nuclear localization sequence of the SV40 large T antigen. This peptide vector localizes rapidly to the cytoplasm then to the nucleus of human fibroblasts (HS-68) within a few minutes and exhibits a high affinity for a single-stranded mRNA encoding the p66 subunit of the HIV-1 reverse transcriptase (in a 100 nM range). The peptide/RNA complex formation involves mainly electrostatic interactions between the basic residues of the peptide and the charges on the phosphate group of the RNA. In the presence of the peptide-vector fluorescently-labelled mRNA is delivered into the cytoplasm of mammalian cells (HS68 human fibroblasts) in less than 1 h with a relatively high efficiency (80%). This new concept based on a peptide-derived vector offers several advantages compared to other compounds commonly used in gene delivery. This vector is highly soluble and exhibits no cytotoxicity at the concentrations used for optimal gene delivery. This result clearly supports the fact that this peptide vector is a powerful tool and that it can be used widely, as much for laboratory research as for new applications and development in gene and/or antisense therapy.

Alternate adenovirus type-pairs for a possible circumvention of host immune response to recombinant adenovirus vectors.

Science.gov (United States)

Nász, I; Adám, E; Lengyel, A

2001-01-01

With the help of monoclonal antibodies the existence of at least 18 different earlier not known intertype (IT) specific epitopes were demonstrated in different numbers and combinations on the hexons of different adenovirus serotypes. The IT specific epitopes play an important role in the experimental gene therapy and in the recombinant adenovirus vaccination because of the harmful immune response of the recipient organisms directed against the many different epitopes of the adenovirus vector. For the elimination of harmful effect the authors suggest the use of multiple vectors, each prepared from different adenovirus serotypes showing the loosest antigenic relationship to each other. The vectors would be used sequentially when second or multiple administration is needed. For this purpose the authors determined and described 31 such adenovirus type-pairs, which are probably the best alternates for sequential use in experimental gene therapy.

The gut microbiota modulates host amino acid and glutathione metabolism in mice

DEFF Research Database (Denmark)

Mardinoglu, Adil; Shoaie, Saeed; Bergentall, Mattias

2015-01-01

, liver, and adipose tissues. We used these functional models to determine the global metabolic differences between CONV-R and GF mice. Based on gene expression data, we found that the gut microbiota affects the host amino acid (AA) metabolism, which leads to modifications in glutathione metabolism...... conventionally raised (CONV-R) and germ-free (GF) mice using gene expression data and tissue-specific genome-scale metabolic models (GEMs). We created a generic mouse metabolic reaction (MMR) GEM, reconstructed 28 tissue-specific GEMs based on proteomics data, and manually curated GEMs for small intestine, colon....... To validate our predictions, we measured the level of AAs and N-acetylated AAs in the hepatic portal vein of CONV-R and GF mice. Finally, we simulated the metabolic differences between the small intestine of the CONV-R and GF mice accounting for the content of the diet and relative gene expression differences...

Infection of non-host model plant species with the narrow-host-range Cacao swollen shoot virus.

Science.gov (United States)

Friscina, Arianna; Chiappetta, Laura; Jacquemond, Mireille; Tepfer, Mark

2017-02-01

Cacao swollen shoot virus (CSSV) is a major pathogen of cacao (Theobroma cacao) in Africa, and long-standing efforts to limit its spread by the culling of infected trees have had very limited success. CSSV is a particularly difficult virus to study, as it has a very narrow host range, limited to several tropical tree species. Furthermore, the virus is not mechanically transmissible, and its insect vector can only be used with difficulty. Thus, the only efficient means to infect cacao plants that have been experimentally described so far are by particle bombardment or the agroinoculation of cacao plants with an infectious clone. We have genetically transformed three non-host species with an infectious form of the CSSV genome: two experimental hosts widely used in plant virology (Nicotiana tabacum and N. benthamiana) and the model species Arabidopsis thaliana. In transformed plants of all three species, the CSSV genome was able to replicate, and, in tobacco, CSSV particles could be observed by immunosorbent electron microscopy, demonstrating that the complete virus cycle could be completed in a non-host plant. These results will greatly facilitate the preliminary testing of CSSV control strategies using plants that are easy to raise and to transform genetically. © 2016 BSPP AND JOHN WILEY & SONS LTD.

Next generation of adeno-associated virus 2 vectors: Point mutations in tyrosines lead to high-efficiency transduction at lower doses

OpenAIRE

Zhong, Li; Li, Baozheng; Mah, Cathryn S.; Govindasamy, Lakshmanan; Agbandje-McKenna, Mavis; Cooper, Mario; Herzog, Roland W.; Zolotukhin, Irene; Warrington, Kenneth H.; Weigel-Van Aken, Kirsten A.; Hobbs, Jacqueline A.; Zolotukhin, Sergei; Muzyczka, Nicholas; Srivastava, Arun

2008-01-01

Recombinant adeno-associated virus 2 (AAV2) vectors are in use in several Phase I/II clinical trials, but relatively large vector doses are needed to achieve therapeutic benefits. Large vector doses also trigger an immune response as a significant fraction of the vectors fails to traffic efficiently to the nucleus and is targeted for degradation by the host cell proteasome machinery. We have reported that epidermal growth factor receptor protein tyrosine kinase (EGFR-PTK) signaling negatively...

An embedded domain specific language for general purpose vectorization

CERN Document Server

Karpinski, Przemyslaw

2017-01-01

Portable SIMD code generation is an open problem in modern High Performance Computing systems. Performance portability can already be achieved, however it might fail when user-framework interaction is required. Of all portable vectorization techniques, explicit vectorization, using wrapper-class libraries, is proven to achieve the fastest performance, however it does not exploit optimization opportunities outside the simplest algebraic primitives. A more advanced language is therefore required, but the design of a new independent language is not feasible due to its high costs. This work describes an Embedded Domain Specific Language for solving generalized 1-D vectorization problems. The language is implemented using C++ as a host language and published as a lightweight library. By decoupling expression creation from evaluation a wider range of problems can be solved, without sacrificing runtime efficiency. In this paper we discuss design patterns necessary, but not limited, to efficient EDSL implementatio...

Effectiveness of synthetic versus natural human volatiles as attractants for Anopheles gambiae (Diptera: Culicidae) sensu stricto

NARCIS (Netherlands)

Smallegange, R.C.; Knols, B.G.J.; Takken, W.

2010-01-01

Females of the African malaria vector, Anopheles gambiae Giles sensu stricto, use human volatiles to find their blood-host. Previous work has shown that ammonia, lactic acid, and aliphatic carboxylic acids significantly affect host orientation and attraction of this species, In the current study,

Live-Attenuated Bacterial Vectors: Tools for Vaccine and Therapeutic Agent Delivery

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Ivan Y. C. Lin

2015-11-01

Full Text Available Genetically attenuated microorganisms, including pathogenic and commensal bacteria, can be engineered to carry and deliver heterologous antigens to elicit host immunity against both the vector as well as the pathogen from which the donor gene is derived. These live attenuated bacterial vectors have been given much attention due to their capacity to induce a broad range of immune responses including localized mucosal, as well as systemic humoral and/or cell-mediated immunity. In addition, the unique tumor-homing characteristics of these bacterial vectors has also been exploited for alternative anti-tumor vaccines and therapies. In such approach, tumor-associated antigen, immunostimulatory molecules, anti-tumor drugs, or nucleotides (DNA or RNA are delivered. Different potential vectors are appropriate for specific applications, depending on their pathogenic routes. In this review, we survey and summarize the main features of the different types of live bacterial vectors and discussed the clinical applications in the field of vaccinology. In addition, different approaches for using live attenuated bacterial vectors for anti-cancer therapy is discussed, and some promising pre-clinical and clinical studies in this field are outlined.

Enhancing Attraction of African Malaria Vectors to a Synthetic Odor Blend

NARCIS (Netherlands)

Mweresa, Collins K.; Mukabana, Wolfgang R.; Omusula, Philemon; Otieno, Bruno; Loon, van Joop J.A.; Takken, Willem

2016-01-01

The deployment of odor-baited tools for sampling and controlling malaria vectors is limited by a lack of potent synthetic mosquito attractants. A synthetic mixture of chemical compounds referred to as “the Mbita blend” (MB) was shown to attract as many host-seeking malaria mosquitoes as attracted

Historical distribution and host-vector diversity of Francisella tularensis, the causative agent of tularemia, in Ukraine.

Science.gov (United States)

Hightower, Jake; Kracalik, Ian T; Vydayko, Nataliya; Goodin, Douglas; Glass, Gregory; Blackburn, Jason K

2014-10-16

Francisella tularensis, the causative agent of tularemia, is a zoonotic agent that remains across much of the northern hemisphere, where it exists in enzootic cycles. In Ukraine, tularemia has a long history that suggests a need for sustained surveillance in natural foci. To better characterize the host-vector diversity and spatial distribution of tularemia, we analyzed historical data from field collections carried out from 1941 to 2008. We analyzed the spatial-temporal distribution of bacterial isolates collected from field samples. Isolates were characterized by source and dominant land cover type. To identify environmental persistence and spatial variation in the source of isolation, we used the space-time permutation and multinomial models in SaTScan. A total of 3,086 positive isolates were taken from 1,084 geographic locations. Isolation of F. tularensis was more frequent among arthropods [n = 2,045 (66.3%)] followed by mammals [n = 619 (20.1%)], water [n = 393 (12.7%)], and farm produce [n = 29 (0.94%)], respectively. Four areas of persistent bacterial isolation were identified. Water and farm produce as sources of bacterial isolation were clustered. Our findings confirm the presence of long-standing natural foci of F. tularensis in Ukraine. Given the history of tularemia as well as its environmental persistence there exists a possibility of (re)emergence in human populations. Heterogeneity in the distribution of tularemia isolate recovery related to land cover type supports the theory of natural nidality and clusters identify areas to target potential sources of the pathogen and improve surveillance.

Identification of Blood Meals from Potential Arbovirus Mosquito Vectors in the Peruvian Amazon Basin

OpenAIRE

Palermo, Pedro M.; Aguilar, Patricia V.; Sanchez, Juan F.; Zorrilla, Víctor; Flores-Mendoza, Carmen; Huayanay, Anibal; Guevara, Carolina; Lescano, Andrés G.; Halsey, Eric S.

2016-01-01

The transmission dynamics of many arboviruses in the Amazon Basin region have not been fully elucidated, including the vectors and natural reservoir hosts. Identification of blood meal sources in field-caught mosquitoes could yield information for identifying potential arbovirus vertebrate hosts. We identified blood meal sources in 131 mosquitoes collected from areas endemic for arboviruses in the Peruvian Department of Loreto by sequencing polymerase chain reaction amplicons of the cytochrom...

A guide to binary vectors and strategies for targeted genome modification in fungi using Agrobacterium tumefaciens-mediated transformation

DEFF Research Database (Denmark)

Frandsen, Rasmus John Normand

2011-01-01

Agrobacterium tumefaciens-mediated transformation (ATMT) of fungi has become a common technique for the study of a wide variety of different fungal species over the past 12years. The discovery that the host range of A. tumefaciens could be extended to include fungi provided an efficient transform......Agrobacterium tumefaciens-mediated transformation (ATMT) of fungi has become a common technique for the study of a wide variety of different fungal species over the past 12years. The discovery that the host range of A. tumefaciens could be extended to include fungi provided an efficient......-regulation of gene expression. This review summarizes the technical advances within the field from 1998 to the summer of 2011, focusing on the development of binary vectors that are compatible with fungal transformation (over 180 general vectors) and methods for constructing binary vectors for targeted integration...

Nesting bird "host funnel" increases mosquito-bird contact rate.

Science.gov (United States)

Caillouët, Kevin A; Riggan, Anna E; Bulluck, Lesley P; Carlson, John C; Sabo, Roy T

2013-03-01

Increases in vector-host contact rates can enhance arbovirus transmission intensity. We investigated weekly fluctuations in contact rates between mosquitoes and nesting birds using the recently described Nest Mosquito Trap (NMT). The number of mosquitoes per nestling increased from nesting season. Our evidence suggests the coincidence of the end of the avian nesting season and increasing mosquito abundances may have caused a "host funnel," concentrating host-seeking mosquitoes to the few remaining nestlings. The relative abundance of mosquitoes collected by the NMT suggests that significantly more Aedes albopictus (Skuse) and Culex pipiens (L.) /restuans (Theobald) sought nesting bird bloodmeals than were predicted by their relative abundances in CO2-baited Centers for Disease Control and Prevention light and gravid traps. Culex salinarius (Coquillett) and Culex erraticus Dyar and Knab were collected in NMTs in proportion to their relative abundances in the generic traps. Temporal host funnels and nesting bird host specificity may enhance arbovirus amplification and explain observed West Nile virus and St. Louis encephalitis virus amplification periods.

Contrasting amino acid profiles among permissive and non-permissive hosts of Candidatus Liberibacter asiaticus, putative causal agent of Huanglongbing.

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Mamoudou Sétamou

Full Text Available Huanglongbing is a devastating disease of citrus. In this study, a comprehensive profile of phloem sap amino acids (AA in four permissive host plants of Candidatus Liberibacter asiaticus (CLas and three non-permissive Rutaceae plants was conducted to gain a better understanding of host factors that may promote or suppress the bacterium. The AA profiles of Diaphorina citri nymphs and adults were similarly analyzed. A total of 38 unique AAs were detected in phloem sap of the various plants and D. citri samples, with phloem sap of young shoots containing more AAs and at higher concentrations than their mature counterparts. All AAs detected in phloem sap of non-permissive plants were also present in CLas -permissive hosts plus additional AAs in the latter class of plants. However, the relative composition of 18 commonly shared AAs varied between CLas -permissive hosts and non-permissive plants. Multivariate analysis with a partial least square discriminant methodology revealed a total of 12 AAs as major factors affecting CLas host status, of which seven were positively related to CLas tolerance/resistance and five positively associated with CLas susceptibility. Most of the AAs positively associated with CLas susceptibility were predominantly of the glutamate family, notably stressed-induced AAs such as arginine, GABA and proline. In contrast, AAs positively correlated with CLas tolerance/resistance were mainly of the serine family. Further analysis revealed that whereas the relative proportions of AAs positively associated with CLas susceptibility did not vary with host developmental stages, those associated with CLas tolerance/resistance increased with flush shoot maturity. Significantly, the proline-to-glycine ratio was determined to be an important discriminating factor for CLas permissivity with higher values characteristic of CLas -permissive hosts. This ratio could be exploited as a biomarker in HLB-resistance breeding programs.

ACID: annotation of cassette and integron data

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Stokes Harold W

2009-04-01

Full Text Available Abstract Background Although integrons and their associated gene cassettes are present in ~10% of bacteria and can represent up to 3% of the genome in which they are found, very few have been properly identified and annotated in public databases. These genetic elements have been overlooked in comparison to other vectors that facilitate lateral gene transfer between microorganisms. Description By automating the identification of integron integrase genes and of the non-coding cassette-associated attC recombination sites, we were able to assemble a database containing all publicly available sequence information regarding these genetic elements. Specialists manually curated the database and this information was used to improve the automated detection and annotation of integrons and their encoded gene cassettes. ACID (annotation of cassette and integron data can be searched using a range of queries and the data can be downloaded in a number of formats. Users can readily annotate their own data and integrate it into ACID using the tools provided. Conclusion ACID is a community resource providing easy access to annotations of integrons and making tools available to detect them in novel sequence data. ACID also hosts a forum to prompt integron-related discussion, which can hopefully lead to a more universal definition of this genetic element.

The Transcriptome of Leishmania major Developmental Stages in Their Natural Sand Fly Vector.

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Inbar, Ehud; Hughitt, V Keith; Dillon, Laura A L; Ghosh, Kashinath; El-Sayed, Najib M; Sacks, David L

2017-04-04

The life cycle of the Leishmania parasite in the sand fly vector involves differentiation into several distinctive forms, each thought to represent an adaptation to specific microenvironments in the midgut of the fly. Based on transcriptome sequencing (RNA-Seq) results, we describe the first high-resolution analysis of the transcriptome dynamics of four distinct stages of Leishmania major as they develop in a natural vector, Phlebotomus duboscqi The early transformation from tissue amastigotes to procyclic promastigotes in the blood-fed midgut was accompanied by the greatest number of differentially expressed genes, including the downregulation of amastins, and upregulation of multiple cell surface proteins, sugar and amino acid transporters, and genes related to glucose metabolism and cell cycle progression. The global changes accompanying post-blood meal differentiation of procyclic promastigotes to the nectomonad and metacyclic stages were less extensive, though each displayed a unique signature. The transcriptome of nectomonads, which has not been studied previously, revealed changes consistent with cell cycle arrest and the upregulation of genes associated with starvation and stress, including autophagic pathways of protein recycling. Maturation to the infective, metacyclic stage was accompanied by changes suggesting preadaptation to the intracellular environment of the mammalian host, demonstrated by the amastigote-like profiles of surface proteins and metabolism-related genes. Finally, a direct comparison between sand fly-derived and culture-derived metacyclics revealed a reassuring similarity between the two forms, with the in vivo forms distinguished mainly by a stronger upregulation of transcripts associated with nutrient stress. IMPORTANCE The life cycle of Leishmania parasites in the sand fly vector includes their growth and development as morphologically distinct forms of extracellular promastigotes found within the different microenvironments of the

Ebola virus host cell entry.

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Sakurai, Yasuteru

2015-01-01

Ebola virus is an enveloped virus with filamentous structure and causes a severe hemorrhagic fever in human and nonhuman primates. Host cell entry is the first essential step in the viral life cycle, which has been extensively studied as one of the therapeutic targets. A virus factor of cell entry is a surface glycoprotein (GP), which is an only essential viral protein in the step, as well as the unique particle structure. The virus also interacts with a lot of host factors to successfully enter host cells. Ebola virus at first binds to cell surface proteins and internalizes into cells, followed by trafficking through endosomal vesicles to intracellular acidic compartments. There, host proteases process GPs, which can interact with an intracellular receptor. Then, under an appropriate circumstance, viral and endosomal membranes are fused, which is enhanced by major structural changes of GPs, to complete host cell entry. Recently the basic research of Ebola virus infection mechanism has markedly progressed, largely contributed by identification of host factors and detailed structural analyses of GPs. This article highlights the mechanism of Ebola virus host cell entry, including recent findings.

Arsenic induces structural and compositional colonic microbiome change and promotes host nitrogen and amino acid metabolism

International Nuclear Information System (INIS)

Dheer, Rishu; Patterson, Jena; Dudash, Mark; Stachler, Elyse N.; Bibby, Kyle J.; Stolz, Donna B.; Shiva, Sruti; Wang, Zeneng; Hazen, Stanley L.; Barchowsky, Aaron; Stolz, John F.

2015-01-01

Chronic exposure to arsenic in drinking water causes cancer and non-cancer diseases. However, mechanisms for chronic arsenic-induced pathogenesis, especially in response to lower exposure levels, are unclear. In addition, the importance of health impacts from xeniobiotic-promoted microbiome changes is just being realized and effects of arsenic on the microbiome with relation to disease promotion are unknown. To investigate impact of arsenic exposure on both microbiome and host metabolism, the stucture and composition of colonic microbiota, their metabolic phenotype, and host tissue and plasma metabolite levels were compared in mice exposed for 2, 5, or 10 weeks to 0, 10 (low) or 250 (high) ppb arsenite (As(III)). Genotyping of colonic bacteria revealed time and arsenic concentration dependent shifts in community composition, particularly the Bacteroidetes and Firmicutes, relative to those seen in the time-matched controls. Arsenic-induced erosion of bacterial biofilms adjacent to the mucosal lining and changes in the diversity and abundance of morphologically distinct species indicated changes in microbial community structure. Bacterical spores increased in abundance and intracellular inclusions decreased with high dose arsenic. Interestingly, expression of arsenate reductase (arsA) and the As(III) exporter arsB, remained unchanged, while the dissimilatory nitrite reductase (nrfA) gene expression increased. In keeping with the change in nitrogen metabolism, colonic and liver nitrite and nitrate levels and ratios changed with time. In addition, there was a concomitant increase in pathogenic arginine metabolites in the mouse circulation. These data suggest that arsenic exposure impacts the microbiome and microbiome/host nitrogen metabolism to support disease enhancing pathogenic phenotypes. - Highlights: • Arsenic exposure induces changes in host and host nitrogen metabolism that cause progresive change in the microbiome. • A polyphasic approach reveals changes

Arsenic induces structural and compositional colonic microbiome change and promotes host nitrogen and amino acid metabolism

Energy Technology Data Exchange (ETDEWEB)

Dheer, Rishu; Patterson, Jena; Dudash, Mark [Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282 (United States); Stachler, Elyse N.; Bibby, Kyle J. [Department of Civil and Environmental Engineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA 15261 (United States); Stolz, Donna B. [Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261 (United States); Shiva, Sruti [Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh 15261 (United States); Vascular Medicine Institute, University of Pittsburgh, Pittsburgh 15261 (United States); Wang, Zeneng; Hazen, Stanley L. [Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195 (United States); Barchowsky, Aaron, E-mail: aab20@pitt.edu [Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh 15261 (United States); Vascular Medicine Institute, University of Pittsburgh, Pittsburgh 15261 (United States); Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA 15219 (United States); Stolz, John F. [Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282 (United States)

2015-12-15

Chronic exposure to arsenic in drinking water causes cancer and non-cancer diseases. However, mechanisms for chronic arsenic-induced pathogenesis, especially in response to lower exposure levels, are unclear. In addition, the importance of health impacts from xeniobiotic-promoted microbiome changes is just being realized and effects of arsenic on the microbiome with relation to disease promotion are unknown. To investigate impact of arsenic exposure on both microbiome and host metabolism, the stucture and composition of colonic microbiota, their metabolic phenotype, and host tissue and plasma metabolite levels were compared in mice exposed for 2, 5, or 10 weeks to 0, 10 (low) or 250 (high) ppb arsenite (As(III)). Genotyping of colonic bacteria revealed time and arsenic concentration dependent shifts in community composition, particularly the Bacteroidetes and Firmicutes, relative to those seen in the time-matched controls. Arsenic-induced erosion of bacterial biofilms adjacent to the mucosal lining and changes in the diversity and abundance of morphologically distinct species indicated changes in microbial community structure. Bacterical spores increased in abundance and intracellular inclusions decreased with high dose arsenic. Interestingly, expression of arsenate reductase (arsA) and the As(III) exporter arsB, remained unchanged, while the dissimilatory nitrite reductase (nrfA) gene expression increased. In keeping with the change in nitrogen metabolism, colonic and liver nitrite and nitrate levels and ratios changed with time. In addition, there was a concomitant increase in pathogenic arginine metabolites in the mouse circulation. These data suggest that arsenic exposure impacts the microbiome and microbiome/host nitrogen metabolism to support disease enhancing pathogenic phenotypes. - Highlights: • Arsenic exposure induces changes in host and host nitrogen metabolism that cause progresive change in the microbiome. • A polyphasic approach reveals changes

Acidification of apple and orange hosts by Penicillium digitatum and Penicillium expansum.

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Vilanova, L; Viñas, I; Torres, R; Usall, J; Buron-Moles, G; Teixidó, N

2014-05-16

New information about virulence mechanisms of Penicillium digitatum and Penicillium expansum could be an important avenue to control fungal diseases. In this study, the ability of P. digitatum and P. expansum to enhance their virulence by locally modulating the pH of oranges and apples was evaluated. For each host, pH changes with a compatible pathogen and a non-host pathogen were recorded, and the levels of different organic acids were evaluated to establish possible relationships with host pH modifications. Moreover, fruits were harvested at three maturity stages to determine whether fruit maturity could affect the pathogens' virulence. The pH of oranges and apples decreased when the compatible pathogens (P. digitatum and P. expansum, respectively) decayed the fruit. The main organic acid detected in P. digitatum-decayed oranges was galacturonic acid produced as a consequence of host maceration in the rot development process. However, the obtained results showed that this acid was not responsible for the pH decrease in decayed orange tissue. The mixture of malic and citric acids could at least contribute to the acidification of P. digitatum-decayed oranges. The pH decrease in P. expansum decayed apples is related to the accumulation of gluconic and fumaric acids. The pH of oranges and apples was not affected when the non-host pathogen was not able to macerate the tissues. However, different organic acid contents were detected in comparison to healthy tissues. The main organic acids detected in P. expansum-oranges were oxalic and gluconic and in P. digitatum-apples were citric, gluconic and galacturonic. Further research is needed to identify the pathogenicity factors of both fungi because the contribution of organic acids has profound implications. Copyright © 2014 Elsevier B.V. All rights reserved.

Identification of a non-host plant of Xylella fastidiosa to rear healthy sharpshooter vectors Identificação de uma planta não-hospedeira de Xylella fastidiosa para criação de insetos vetores sadios

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Rosangela Cristina Marucci

2003-12-01

Full Text Available Rearing leafhopper (Hemiptera: Cicadellidae vectors free of Xylella fastidiosa is a requirement for studies of various aspects of vector-pathogen interactions. The selection of a plant that allows vector development but not bacterial multiplication is desirable to produce healthy vectors. In this study, two leafhopper hosts, Vernonia condensata ('boldo' and Aloysia virgata ('lixeira' were needle inoculated with citrus and coffee strains of X. fastidiosa to evaluate if these plants support pathogen colonization. The inoculated plants did not present symptoms and the pathogen was not detected by culture and PCR tests, neither soon after inoculation (7-14 days nor later, at 1, 4, 6 and 12 months after inoculation. To obtain healthy adults of the leafhopper vectors Acrogonia citrina, Bucephalogonia xanthophis, Dilobopterus costalimai, Homalodisca ignorata and Oncometopia facialis, early-instar nymphs were reared on V. condensata. X. fastidiosa was not detected in any of 175 adults obtained. V. condensata and A. virgata are nonpropagative hosts of X. fastidiosa and enable the production of healthy leafhoppers for vector studies.A obtenção de cigarrinhas (Hemiptera: Cicadellidae livres de Xylella fastidiosa é importante para estudos de interação entre essa bactéria e seus vetores, sendo desejável a seleção de uma planta que permita a criação desses insetos, mas não a multiplicação da bactéria. Neste estudo, duas plantas hospedeiras de cigarrinhas, Vernonia condensata (boldo e Aloysia virgata (lixeira, foram inoculadas por agulha com as estirpes de citros e de cafeeiro de X. fastidiosa, para avaliar a possibilidade deste patógeno colonizá-las. Não foram observados sintomas, nem se detectou a bactéria por isolamento em meio de cultura e/ou PCR em períodos curtos (7 e 14 dias ou longos (1, 4, 6 e 12 meses após a inoculação. Para obtenção de adultos sadios das cigarrinhas vetoras, Acrogonia citrina, Bucephalogonia xanthophis

DNA transformations of Candida tropicalis with replicating and integrative vectors.

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Sanglard, D; Fiechter, A

1992-12-01

The alkane-assimilating yeast Candida tropicalis was used as a host for DNA transformations. A stable ade2 mutant (Ha900) obtained by UV-mutagenesis was used as a recipient for different vectors carrying selectable markers. A first vector, pMK16, that was developed for the transformation of C. albicans and carries an ADE2 gene marker and a Candida autonomously replicating sequence (CARS) element promoting autonomous replication, was compatible for transforming Ha900. Two transformant types were observed: (i) pink transformants which easily lose pMK16 under non-selective growth conditions; (ii) white transformants, in which the same plasmid exhibited a higher mitotic stability. In both cases pMK16 could be rescued from these cells in Escherichia coli. A second vector, pADE2, containing the isolated C. tropicalis ADE2, gene, was used to transform Ha900. This vector integrated in the yeast genome at homologous sites of the ade2 locus. Different integration types were observed at one or both ade2 alleles in single or in tandem repeats.

High-Throughput Dissection of AAV-Host Interactions: The Fast and the Curious.

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Herrmann, Anne-Kathrin; Grimm, Dirk

2018-05-18

Over fifty years after its initial description, Adeno-associated virus (AAV) remains a most exciting but also most elusive study object in basic or applied virology. On the one hand, its simple structure not only facilitates investigations into virus biology, but combined with the availability of numerous natural AAV variants with distinct infection efficiency and specificity also makes AAV a preferred substrate for engineering of gene delivery vectors. On the other hand, it is striking to witness a recent flurry of reports that highlight and partially close persistent gaps in our understanding of AAV virus and vector biology. This is all the more perplexing considering that recombinant AAVs have already been used in >160 clinical trials and recently been commercialized as gene therapeutics. Here, we discuss a reason for these advances in AAV research, namely, the advent and application of powerful high-throughput technology for dissection of AAV-host interactions and optimization of AAV gene therapy vectors. As relevant examples, we focus on the discovery of (i) a "new" cellular AAV receptor, AAVR, (ii) host restriction factors for AAV entry, and (iii) AAV capsid determinants that mediate trafficking through the blood-brain barrier. While (i)/(ii) are prototypes of extra- or intracellular AAV host factors that were identified via high-throughput screenings, (iii) exemplifies the power of molecular evolution to investigate the virus itself. In the future, we anticipate that these and other key technologies will continue to accelerate the dissection of AAV biology and will yield a wealth of new designer viruses for clinical use. Copyright © 2018. Published by Elsevier Ltd.

Retroviral Vectors: Post Entry Events and Genomic Alterations

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Christof von Kalle

2011-04-01

Full Text Available The curative potential of retroviral vectors for somatic gene therapy has been demonstrated impressively in several clinical trials leading to sustained long-term correction of the underlying genetic defect. Preclinical studies and clinical monitoring of gene modified hematopoietic stem and progenitor cells in patients have shown that biologically relevant vector induced side effects, ranging from in vitro immortalization to clonal dominance and oncogenesis in vivo, accompany therapeutic efficiency of integrating retroviral gene transfer systems. Most importantly, it has been demonstrated that the genotoxic potential is not identical among all retroviral vector systems designed for clinical application. Large scale viral integration site determination has uncovered significant differences in the target site selection of retrovirus subfamilies influencing the propensity for inducing genetic alterations in the host genome. In this review we will summarize recent insights gained on the mechanisms of insertional mutagenesis based on intrinsic target site selection of different retrovirus families. We will also discuss examples of side effects occurring in ongoing human gene therapy trials and future prospectives in the field.

Integrated pest management and allocation of control efforts for vector-borne diseases

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Ginsberg, H.S.

2001-01-01

Applications of various control methods were evaluated to determine how to integrate methods so as to minimize the number of human cases of vector-borne diseases. These diseases can be controlled by lowering the number of vector-human contacts (e.g., by pesticide applications or use of repellents), or by lowering the proportion of vectors infected with pathogens (e.g., by lowering or vaccinating reservoir host populations). Control methods should be combined in such a way as to most efficiently lower the probability of human encounter with an infected vector. Simulations using a simple probabilistic model of pathogen transmission suggest that the most efficient way to integrate different control methods is to combine methods that have the same effect (e.g., combine treatments that lower the vector population; or combine treatments that lower pathogen prevalence in vectors). Combining techniques that have different effects (e.g., a technique that lowers vector populations with a technique that lowers pathogen prevalence in vectors) will be less efficient than combining two techniques that both lower vector populations or combining two techniques that both lower pathogen prevalence, costs being the same. Costs of alternative control methods generally differ, so the efficiency of various combinations at lowering human contact with infected vectors should be estimated at available funding levels. Data should be collected from initial trials to improve the effects of subsequent interventions on the number of human cases.

Vectors of Crimean Congo Hemorrhagic Fever Virus in Iran

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Zakkyeh Telmadarraiy

2015-10-01

Full Text Available Background: Ticks are important vectors and reservoirs of Crimean Congo Hemorrhagic Fever (CCHF virus. Human beings may be infected whenever the normal life cycle of the infected ticks on non- human vertebrate hosts is interrupted by the undesirable presence of humans in the cycle. A total of 26 species of Argasid and Ixodid ticks have been recorded in Iran; including nine Hyalomma, two Rhipicephalus, two Dermacentor, five Haemaphysalis, two Boophilus, one Ixodes and two Argas as well as three Ornithodoros species as blood sucking ectoparasites of livestock and poultries. The present paper reviews tick vectors of CCHF virus in Iran, focusing on the role of ticks in different provinces of Iran using reverse transcription polymerase chain reaction (RT-PCR assay.Methods: During ten years study, 1054 tick specimens; including two species of Argasidae and 17 species of Ixodidae were examined for their infection to CCHF virus genome. The output of all studies as well as related publications were discussed in the current paper.Results: The results show that Rhipicephalus sanguineus, Hyalomma marginatum, H. anatolicum, H. asiaticum and H. dromedarii were known as the most frequent species which were positive for CCHF virus.Conclusion: The status of ticks which were positive for CCHF virus revealed that unlike the most common idea that Hyalomma species are the most important vectors of CCHF virus, other ticks including Rhipicephalus,Haemaphysalis and Dermacentor can be reservoir of this virus; thus, considering geographical distribution, type of host and environmental conditions, different tick control measurements should be carried out in areas with high incidence of CCHF disease.

Vectors of Crimean Congo Hemorrhagic Fever Virus in Iran

Science.gov (United States)

Telmadarraiy, Zakkyeh; Chinikar, Sadegh; Vatandoost, Hassan; Faghihi, Faezeh; Hosseini-Chegeni, Asadollah

2015-01-01

Background: Ticks are important vectors and reservoirs of Crimean Congo Hemorrhagic Fever (CCHF) virus. Human beings may be infected whenever the normal life cycle of the infected ticks on non-human vertebrate hosts is interrupted by the undesirable presence of humans in the cycle. A total of 26 species of Argasid and Ixodid ticks have been recorded in Iran; including nine Hyalomma, two Rhipicephalus, two Dermacentor, five Haemaphysalis, two Boophilus, one Ixodes and two Argas as well as three Ornithodoros species as blood sucking ectoparasites of livestock and poultries. The present paper reviews tick vectors of CCHF virus in Iran, focusing on the role of ticks in different provinces of Iran using reverse transcription polymerase chain reaction (RT-PCR) assay. Methods: During ten years study, 1054 tick specimens; including two species of Argasidae and 17 species of Ixodidae were examined for their infection to CCHF virus genome. The output of all studies as well as related publications were discussed in the current paper. Results: The results show that Rhipicephalus sanguineus, Hyalomma marginatum, H. anatolicum, H. asiaticum and H. dromedarii were known as the most frequent species which were positive for CCHF virus. Conclusion: The status of ticks which were positive for CCHF virus revealed that unlike the most common idea that Hyalomma species are the most important vectors of CCHF virus, other ticks including Rhipicephalus, Haemaphysalis and Dermacentor can be reservoir of this virus; thus, considering geographical distribution, type of host and environmental conditions, different tick control measurements should be carried out in areas with high incidence of CCHF disease. PMID:26623426

Insect Cells as Hosts for Recombinat Proteins

OpenAIRE

Murwani, Retno

1997-01-01

Since the development of recombinant baculovirus expression system, insect cell culture has rapidly gain popularity as the method of choice for production of a variety of biologically active proteins. Up to date tens of recombinant protein have been produced by this method commercially or non-commercially and have been widely used for research. This review describes the basic concept of baculovirus expression vector and the use of insect cells as host for recombinant proteins. Examples of the...

Reporter gene expression in fish following cutaneous infection with pantropic retroviral vectors.

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Paul, T A; Burns, J C; Shike, H; Getchell, R; Bowser, P R; Whitlock, K E; Casey, J W

2001-06-01

A central issue in gene delivery systems is choosing promoters that will direct defined and sustainable levels of gene expression. Pantropic retroviral vectors provide a means to insert genes into either somatic or germline cells. In this study, we focused on somatic cell infection by evaluating the activity of 3 promoters inserted by vectors into fish cell lines and fish skin using pantropic retroviruses. In bluegill and zebrafish cell lines, the highest levels of luciferase expression were observed from the 5' murine leukemia virus long terminal repeat of the retroviral vector. The Rous sarcoma virus long terminal repeat and cytomegalovirus early promoter, as internal promoters, generated lower levels of luciferase. Luciferase reporter vectors infected zebrafish skin, as measured by the presence of viral DNA, and expressed luciferase. We infected developing walleye dermal sarcomas with retroviral vectors to provide an environment with enhanced cell proliferation, a condition necessary for integration of the provirus into the host genome. We demonstrated a 4-fold to 7-fold increase in luciferase gene expression in tumor tissue over infections in normal walleye skin.

Viral vector-based tools advance knowledge of basal ganglia anatomy and physiology.

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Sizemore, Rachel J; Seeger-Armbruster, Sonja; Hughes, Stephanie M; Parr-Brownlie, Louise C

2016-04-01

Viral vectors were originally developed to deliver genes into host cells for therapeutic potential. However, viral vector use in neuroscience research has increased because they enhance interpretation of the anatomy and physiology of brain circuits compared with conventional tract tracing or electrical stimulation techniques. Viral vectors enable neuronal or glial subpopulations to be labeled or stimulated, which can be spatially restricted to a single target nucleus or pathway. Here we review the use of viral vectors to examine the structure and function of motor and limbic basal ganglia (BG) networks in normal and pathological states. We outline the use of viral vectors, particularly lentivirus and adeno-associated virus, in circuit tracing, optogenetic stimulation, and designer drug stimulation experiments. Key studies that have used viral vectors to trace and image pathways and connectivity at gross or ultrastructural levels are reviewed. We explain how optogenetic stimulation and designer drugs used to modulate a distinct pathway and neuronal subpopulation have enhanced our mechanistic understanding of BG function in health and pathophysiology in disease. Finally, we outline how viral vector technology may be applied to neurological and psychiatric conditions to offer new treatments with enhanced outcomes for patients. Copyright © 2016 the American Physiological Society.

Synthetic blends of volatile, phytopathogen-induced odorants can be used to manipulate vector behavior.

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Alexander eAksenov

2014-12-01

Full Text Available Volatile organic compounds (VOCs are emitted from all plants and these VOCs are important means of communication between plants and insects. It has been documented that pathogen infections alter VOC profiles rendering infected plants more attractive to specific vectors transmitting these pathogens than uninfected plants, thus potentially aiding in pathogen propagation. Mimicking these chemical cues might enable insect attraction away from the plant or disruption of host finding behavior of the vector. However, the practical implications have not been fully explored. We used citrus, Diaphorina citri and huanglongbing (HLB as a model host-vector-disease system because HLB threatens citrus production worldwide and is similar to other critical diseases of food crops, such as Zebra Chip affecting potato. We formulated a synthetic chemical blend using selected HLB-specific biomarker compounds, and tested the blend with the Attenu assay system for chemosensory proteins. The Attenu assay system is a procedure that identifies interactions between insect chemosensory proteins and their ligands. We found that an equimolar mixture of compounds mimicking the volatile profile of HLB-infected citrus bound chemosensory proteins. Further investigation of this blend in laboratory behavioral assays resulted in development of a synthetic lure that was more attractive to D. citri than natural citrus tree volatiles. This strategy could provide a new route to produce chemical lures for vector population control for a variety of plant and/or animal systems and it may result in the development of a practical lure for monitoring vectors of disease, such as D. citri.

WNV infection - an emergent vector borne viral infection in Serbia: Current situation

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Petrović Tamaš

2015-01-01

Full Text Available West Nile virus (WNV is a neurovirulent mosquito-borne Flavivirus with zoonotic potential. Virus is maintained in nature in an enzootic transmission cycle between avian hosts and mosquito vectors, but occasionally infects other vertebrates. The infection in horses and humans can be asymptomatic or it can have different clinical manifestations ranging from light febrile diseases to fatal meningoencephalitis. Recently, the number, frequency and severity of outbreaks with neurological consequences for birds, humans and horses have increased dramatically throughout central and south Europe, including Serbia, posing a serious veterinary and public health problem. The emergency of WNV infections in Serbia is described through the current epidemiology situation based on recent data on the incidence of WNV infection among virus natural hosts and vectors; sentinel (horses and other animal species, and in human population. The results of the WNV serology studies conducted on horse blood samples collected in different occasions during the last six years, and the results of the serology studies conducted among other animal species like pigs, wild boars, roe deer and dogs in Serbia are presented and discussed. Also, the results of the first studies on WNV presence in mosquito vectors and in wild birds as virus natural hosts in Serbia are presented and analyzed. In addition, the data on the WNV serology studies conducted in human population in Serbia in the last few years, and the existing data of WNV outbreaks in 2012 and 2013 are included. Regarding the existing knowledge on WNV epidemiology situation, the crucial role of veterinary service in early detection of WNV presence and ongoing national program of WNV surveillance in sentinel animals, mosquitoes and wild birds are discussed.

High dietary level of synthetic vitamin E on lipid peroxidation, membrane fatty acid composition and cytotoxicity in breast cancer xenograft and in mouse host tissue

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Barnes Christopher J

2003-03-01

Full Text Available Abstract Background d-α-tocopherol is a naturally occurring form of vitamin E not previously known to have antitumor activity. Synthetic vitamin E (sE is a commonly used dietary supplement consisting of a mixture of d-α-tocopherol and 7 equimolar stereoisomers. To test for antilipid peroxidation and for antitumor activity of sE supplementation, two groups of nude mice bearing a MDA-MB 231 human breast cancer tumor were fed an AIN-76 diet, one with and one without an additional 2000 IU/kg dry food (equivalent to 900 mg of all-rac-α-tocopherol or sE. This provided an intake of about 200 mg/kg body weight per day. The mice were killed at either 2 or 6 weeks after the start of dietary intervention. During necropsy, tumor and host tissues were excised for histology and for biochemical analyses. Results Tumor growth was significantly reduced by 6 weeks of sE supplementation. Thiobarbituric acid reactive substances, an indicator of lipid peroxidation, were suppressed in tumor and in host tissues in sE supplemented mice. In the sE treated mice, the fatty acid composition of microsomal and mitochondrial membranes of tumor and host tissues had proportionately less linoleic acid (n-6 C 18-2, similar levels of arachidonic acid (n-6 C 20-4, but more docosahexanoic acid (n-3 C 22-6. The sE supplementation had no significant effect on blood counts or on intestinal histology but gave some evidence of cardiac toxicity as judged by myocyte vacuoles and by an indicator of oxidative stress (increased ratio of Mn SOD mRNA over GPX1 mRNA. Conclusions At least one of the stereoisomers in sE has antitumor activity. Synthetic vitamin E appears to preferentially stabilize membrane fatty acids with more double bonds in the acyl chain. Although sE suppressed tumor growth and lipid peroxidation, it may have side-effects in the heart.

Hemi-nested PCR and RFLP methodologies for identifying blood meals of the Chagas disease vector, Triatoma infestans.

Science.gov (United States)

Roellig, Dawn M; Gomez-Puerta, Luis A; Mead, Daniel G; Pinto, Jesus; Ancca-Juarez, Jenny; Calderon, Maritza; Bern, Caryn; Gilman, Robert H; Cama, Vitaliano A

2013-01-01

Trypanosoma cruzi, the etiologic agent of Chagas disease, is transmitted by hematophagous reduviid bugs within the subfamily Triatominae. These vectors take blood meals from a wide range of hosts, and their feeding behaviors have been used to investigate the ecology and epidemiology of T. cruzi. In this study we describe two PCR-based methodologies that amplify a fragment of the 16S mitochondrial rDNA, aimed to improve the identification of blood meal sources for Triatoma infestans: a.--Sequence analyses of two heminested PCRs that allow the identification of mammalian and avian species, and b.--restriction fragment length polymorphism (RFLP) analysis from the mammalian PCR to identify and differentiate multi-host blood meals. Findings from both methodologies indicate that host DNA could be detected and the host species identified in samples from laboratory reared and field collected triatomines. The implications of this study are two-fold. First, these methods can be used in areas where the fauna diversity and feeding behavior of the triatomines are unknown. Secondly, the RFLP method led to the identification of multi-host DNA from T. infestans gut contents, enhancing the information provided by this assay. These tools are important contributions for ecological and epidemiological studies of vector-borne diseases.

Culicoides (Diptera: Ceratopogonidae) host preferences and biting rates in the Netherlands : comparing cattle, sheep and the black-light suction trap

NARCIS (Netherlands)

Elbers, A.R.W.; Meiswinkel, R.

2014-01-01

Host preference is an important determinant of feeding behaviour in biting insects and a critical component in the transmission of vector-borne diseases. The aim of the study was to quantify Culicoides (Diptera: Ceratopogonidae) host preferences and biting rates using tethered livestock at pasture

Modulation of Host Learning in Aedes aegypti Mosquitoes.

Science.gov (United States)

Vinauger, Clément; Lahondère, Chloé; Wolff, Gabriella H; Locke, Lauren T; Liaw, Jessica E; Parrish, Jay Z; Akbari, Omar S; Dickinson, Michael H; Riffell, Jeffrey A

2018-02-05

How mosquitoes determine which individuals to bite has important epidemiological consequences. This choice is not random; most mosquitoes specialize in one or a few vertebrate host species, and some individuals in a host population are preferred over others. Mosquitoes will also blood feed from other hosts when their preferred is no longer abundant, but the mechanisms mediating these shifts between hosts, and preferences for certain individuals within a host species, remain unclear. Here, we show that olfactory learning may contribute to Aedes aegypti mosquito biting preferences and host shifts. Training and testing to scents of humans and other host species showed that mosquitoes can aversively learn the scent of specific humans and single odorants and learn to avoid the scent of rats (but not chickens). Using pharmacological interventions, RNAi, and CRISPR gene editing, we found that modification of the dopamine-1 receptor suppressed their learning abilities. We further show through combined electrophysiological and behavioral recordings from tethered flying mosquitoes that these odors evoke changes in both behavior and antennal lobe (AL) neuronal responses and that dopamine strongly modulates odor-evoked responses in AL neurons. Not only do these results provide direct experimental evidence that olfactory learning in mosquitoes can play an epidemiological role, but collectively, they also provide neuroanatomical and functional demonstration of the role of dopamine in mediating this learning-induced plasticity, for the first time in a disease vector insect. Copyright © 2017 Elsevier Ltd. All rights reserved.

Eilat virus displays a narrow mosquito vector range.

Science.gov (United States)

Nasar, Farooq; Haddow, Andrew D; Tesh, Robert B; Weaver, Scott C

2014-12-17

Most alphaviruses are arthropod-borne and utilize mosquitoes as vectors for transmission to susceptible vertebrate hosts. This ability to infect both mosquitoes and vertebrates is essential for maintenance of most alphaviruses in nature. A recently characterized alphavirus, Eilat virus (EILV), isolated from a pool of Anopheles coustani s.I. is unable to replicate in vertebrate cell lines. The EILV host range restriction occurs at both attachment/entry as well as genomic RNA replication levels. Here we investigated the mosquito vector range of EILV in species encompassing three genera that are responsible for maintenance of other alphaviruses in nature. Susceptibility studies were performed in four mosquito species: Aedes albopictus, A. aegypti, Anopheles gambiae, and Culex quinquefasciatus via intrathoracic and oral routes utilizing EILV and EILV expressing red fluorescent protein (-eRFP) clones. EILV-eRFP was injected at 10(7) PFU/mL to visualize replication in various mosquito organs at 7 days post-infection. Mosquitoes were also injected with EILV at 10(4)-10(1) PFU/mosquito and virus replication was measured via plaque assays at day 7 post-infection. Lastly, mosquitoes were provided bloodmeals containing EILV-eRFP at doses of 10(9), 10(7), 10(5) PFU/mL, and infection and dissemination rates were determined at 14 days post-infection. All four species were susceptible via the intrathoracic route; however, replication was 10-100 fold less than typical for most alphaviruses, and infection was limited to midgut-associated muscle tissue and salivary glands. A. albopictus was refractory to oral infection, while A. gambiae and C. quinquefasciatus were susceptible only at 10(9) PFU/mL dose. In contrast, A. aegypti was susceptible at both 10(9) and 10(7) PFU/mL doses, with body infection rates of 78% and 63%, and dissemination rates of 26% and 8%, respectively. The exclusion of vertebrates in its maintenance cycle may have facilitated the adaptation of EILV to a single

PIWIs Go Viral: Arbovirus-Derived piRNAs in Vector Mosquitoes.

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Pascal Miesen

2016-12-01

Full Text Available Vector mosquitoes are responsible for transmission of the majority of arthropod-borne (arbo- viruses. Virus replication in these vectors needs to be sufficiently high to permit efficient virus transfer to vertebrate hosts. The mosquito immune response therefore is a key determinant for arbovirus transmission. Mosquito antiviral immunity is primarily mediated by the small interfering RNA pathway. Besides this well-established antiviral machinery, the PIWI-interacting RNA (piRNA pathway processes viral RNA into piRNAs. In recent years, significant progress has been made in characterizing the biogenesis and function of these viral piRNAs. In this review, we discuss these developments, identify knowledge gaps, and suggest directions for future research.

Progress and prospects: foamy virus vectors enter a new age.

Science.gov (United States)

Erlwein, O; McClure, M O

2010-12-01

Foamy viruses, distantly related to the major subfamily of Retroviruses, Orthoretroviruses that include oncoviruses (for example, murine leukemia virus (MLV)) and lentiviruses (human immunodeficiency virus (HIV)), are endemic in mammalian species, but not in human populations. Humans infected by accidental or occupational exposure remain well. The virus is not transmitted to others, nor is it associated with any disease. These features added to its broad host range, efficient transduction of progenitor cells and an integration profile less likely to induce insertional mutagenesis, make these viruses attractive as vectors. Long-term reversal of disease phenotype in dogs with the genetic defect, leukocyte adhesion deficiency, by foamy virus vector therapy strengthens the case for their clinical exploitation.

Correction of acid beta-galactosidase deficiency in GM1 gangliosidosis human fibroblasts by retrovirus vector-mediated gene transfer: higher efficiency of release and cross-correction by the murine enzyme.

Science.gov (United States)

Sena-Esteves, M; Camp, S M; Alroy, J; Breakefield, X O; Kaye, E M

2000-03-20

Mutations in the lysosomal acid beta-galactosidase (EC 3.2.1.23) underlie two different disorders: GM1 gangliosidosis, which involves the nervous system and visceral organs to varying extents, and Morquio's syndrome type B (Morquio B disease), which is a skeletal-connective tissue disease without any CNS symptoms. This article shows that transduction of human GM1 gangliosidosis fibroblasts with retrovirus vectors encoding the human acid beta-galactosidase cDNA leads to complete correction of the enzymatic deficiency. The newly synthesized enzyme is correctly processed and targeted to the lysosomes in transduced cells. Cross-correction experiments using retrovirus-modified cells as enzyme donors showed, however, that the human enzyme is transferred at low efficiencies. Experiments using a different retrovirus vector carrying the human cDNA confirmed this observation. Transduction of human GM1 fibroblasts and mouse NIH 3T3 cells with a retrovirus vector encoding the mouse beta-galactosidase cDNA resulted in high levels of enzymatic activity. Furthermore, the mouse enzyme was found to be transferred to human cells at high efficiency. Enzyme activity measurements in medium conditioned by genetically modified cells suggest that the human beta-galactosidase enzyme is less efficiently released to the extracellular space than its mouse counterpart. This study suggests that lysosomal enzymes, contrary to the generalized perception in the field of gene therapy, may differ significantly in their properties and provides insights for design of future gene therapy interventions in acid beta-galactosidase deficiency.

Gene Transfer of Glutamic Acid Decarboxylase 67 by Herpes Simplex Virus Vectors Suppresses Neuropathic Pain Induced by Human Immunodeficiency Virus gp120 Combined with ddC in Rats.

Science.gov (United States)

Kanao, Megumi; Kanda, Hirotsugu; Huang, Wan; Liu, Shue; Yi, Hyun; Candiotti, Keith A; Lubarsky, David A; Levitt, Roy C; Hao, Shuanglin

2015-06-01

Human immunodeficiency virus (HIV)-related painful sensory neuropathies primarily consist of the HIV infection-related distal sensory polyneuropathy and antiretroviral toxic neuropathies. Pharmacotherapy provides only partial relief of pain in patients with HIV/acquired immune deficiency syndrome because little is known about the exact neuropathological mechanisms for HIV-associated neuropathic pain (NP). Hypofunction of γ-aminobutyric acid (GABA) GABAergic inhibitory mechanisms has been reported after peripheral nerve injury. In this study, we tested the hypothesis that HIV gp120 combined with antiretroviral therapy reduces spinal GABAergic inhibitory tone and that restoration of GABAergic inhibitory tone will reduce HIV-related NP in a rat model. The application of recombinant HIV-1 envelope protein gp120 into the sciatic nerve plus systemic ddC (one antiretroviral drug) induced mechanical allodynia. The hind paws of rats were inoculated with replication-defective herpes simplex virus (HSV) vectors genetically encoding gad1 gene to express glutamic acid decarboxylase 67 (GAD67), an enzyme that catalyzes the decarboxylation of glutamate to GABA. Mechanical threshold was tested using von Frey filaments before and after treatments with the vectors. The expression of GAD67 in both the lumbar spinal cord and the L4-5 dorsal root ganglia was examined using western blots. The expression of mitochondrial superoxide in the spinal dorsal horn was examined using MitoSox imaging. The immunoreactivity of spinal GABA, pCREB, and pC/EBPβ was tested using immunohistochemistry. In the gp120 with ddC-induced neuropathic pain model, GAD67 expression mediated by the HSV vector caused an elevation of mechanical threshold that was apparent on day 3 after vector inoculation. The antiallodynic effect of the single HSV vector inoculation expressing GAD67 lasted >28 days. The area under the time-effect curves in the HSV vector expressing GAD67 was increased compared with that in the

VirHostNet 2.0: surfing on the web of virus/host molecular interactions data.

Science.gov (United States)

Guirimand, Thibaut; Delmotte, Stéphane; Navratil, Vincent

2015-01-01

VirHostNet release 2.0 (http://virhostnet.prabi.fr) is a knowledgebase dedicated to the network-based exploration of virus-host protein-protein interactions. Since the previous VirhostNet release (2009), a second run of manual curation was performed to annotate the new torrent of high-throughput protein-protein interactions data from the literature. This resource is shared publicly, in PSI-MI TAB 2.5 format, using a PSICQUIC web service. The new interface of VirHostNet 2.0 is based on Cytoscape web library and provides a user-friendly access to the most complete and accurate resource of virus-virus and virus-host protein-protein interactions as well as their projection onto their corresponding host cell protein interaction networks. We hope that the VirHostNet 2.0 system will facilitate systems biology and gene-centered analysis of infectious diseases and will help to identify new molecular targets for antiviral drugs design. This resource will also continue to help worldwide scientists to improve our knowledge on molecular mechanisms involved in the antiviral response mediated by the cell and in the viral strategies selected by viruses to hijack the host immune system. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Predicting Rift Valley Fever Inter-epidemic Activities and Outbreak Patterns: Insights from a Stochastic Host-Vector Model.

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Sansao A Pedro

2016-12-01

Full Text Available Rift Valley fever (RVF outbreaks are recurrent, occurring at irregular intervals of up to 15 years at least in East Africa. Between outbreaks disease inter-epidemic activities exist and occur at low levels and are maintained by female Aedes mcintoshi mosquitoes which transmit the virus to their eggs leading to disease persistence during unfavourable seasons. Here we formulate and analyse a full stochastic host-vector model with two routes of transmission: vertical and horizontal. By applying branching process theory we establish novel relationships between the basic reproduction number, R0, vertical transmission and the invasion and extinction probabilities. Optimum climatic conditions and presence of mosquitoes have not fully explained the irregular oscillatory behaviour of RVF outbreaks. Using our model without seasonality and applying van Kampen system-size expansion techniques, we provide an analytical expression for the spectrum of stochastic fluctuations, revealing how outbreaks multi-year periodicity varies with the vertical transmission. Our theory predicts complex fluctuations with a dominant period of 1 to 10 years which essentially depends on the efficiency of vertical transmission. Our predictions are then compared to temporal patterns of disease outbreaks in Tanzania, Kenya and South Africa. Our analyses show that interaction between nonlinearity, stochasticity and vertical transmission provides a simple but plausible explanation for the irregular oscillatory nature of RVF outbreaks. Therefore, we argue that while rainfall might be the major determinant for the onset and switch-off of an outbreak, the occurrence of a particular outbreak is also a result of a build up phenomena that is correlated to vertical transmission efficiency.

Host cells and methods for production of isobutanol

Science.gov (United States)

Anthony, Larry Cameron; He, Hongxian; Huang, Lixuan Lisa; Okeefe, Daniel P.; Kruckeberg, Arthur Leo; Li, Yougen; Maggio-Hall, Lori; McElvain, Jessica; Nelson, Mark J.; Patnaik, Ranjan; Rothman, Steven Cary

2017-10-17

Provided herein are recombinant yeast host cells and methods for their use for production of isobutanol. Yeast host cells provided comprise an isobutanol biosynthetic pathway and at least one of reduced or eliminated aldehyde dehydrogenase activity, reduced or eliminated acetolactate reductase activity; or a heterologous polynucleotide encoding a polypeptide having ketol-acid reductoisomerase activity.

Viral pathogen production in a wild grass host driven by host growth and soil nitrogen.

Science.gov (United States)

Whitaker, Briana K; Rúa, Megan A; Mitchell, Charles E

2015-08-01

Nutrient limitation is a basic ecological constraint that has received little attention in studies on virus production and disease dynamics. Nutrient availability could directly limit the production of viral nucleic acids and proteins, or alternatively limit host growth and thus indirectly limit metabolic pathways necessary for viral replication. In order to compare direct and indirect effects of nutrient limitation on virus production within hosts, we manipulated soil nitrogen (N) and phosphorus (P) availability in a glasshouse for the wild grass host Bromus hordeaceus and the viral pathogen Barley yellow dwarf virus-PAV. We found that soil N additions increased viral concentrations within host tissues, and the effect was mediated by host growth. Specifically, in statistical models evaluating the roles of host biomass production, leaf N and leaf P, viral production depended most strongly on host biomass, rather than the concentration of either nutrient. Furthermore, at low soil N, larger plants supported greater viral concentrations than smaller ones, whereas at high N, smaller plants supported greater viral concentrations. Our results suggest that enhanced viral productivity under N enrichment is an indirect consequence of nutrient stimulation to host growth rate. Heightened pathogen production in plants has important implications for a world facing increasing rates of nutrient deposition. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Seasonal and regional dynamics of M. ulcerans transmission in environmental context: deciphering the role of water bugs as hosts and vectors.

Science.gov (United States)

Marion, Estelle; Eyangoh, Sara; Yeramian, Edouard; Doannio, Julien; Landier, Jordi; Aubry, Jacques; Fontanet, Arnaud; Rogier, Christophe; Cassisa, Viviane; Cottin, Jane; Marot, Agnès; Eveillard, Matthieu; Kamdem, Yannick; Legras, Pierre; Deshayes, Caroline; Saint-André, Jean-Paul; Marsollier, Laurent

2010-07-06

Buruli ulcer, the third mycobacterial disease after tuberculosis and leprosy, is caused by the environmental mycobacterium M. ulcerans. Various modes of transmission have been suspected for this disease, with no general consensus acceptance for any of them up to now. Since laboratory models demonstrated the ability of water bugs to transmit M. ulcerans, a particular attention is focused on the transmission of the bacilli by water bugs as hosts and vectors. However, it is only through detailed knowledge of the biodiversity and ecology of water bugs that the importance of this mode of transmission can be fully assessed. It is the objective of the work here to decipher the role of water bugs in M. ulcerans ecology and transmission, based on large-scale field studies. The distribution of M. ulcerans-hosting water bugs was monitored on previously unprecedented time and space scales: a total of 7,407 water bugs, belonging to large number of different families, were collected over one year, in Buruli ulcer endemic and non endemic areas in central Cameroon. This study demonstrated the presence of M. ulcerans in insect saliva. In addition, the field results provided a full picture of the ecology of transmission in terms of biodiversity and detailed specification of seasonal and regional dynamics, with large temporal heterogeneity in the insect tissue colonization rate and detection of M. ulcerans only in water bug tissues collected in Buruli ulcer endemic areas. The large-scale detection of bacilli in saliva of biting water bugs gives enhanced weight to their role in M. ulcerans transmission. On practical grounds, beyond the ecological interest, the results concerning seasonal and regional dynamics can provide an efficient tool in the hands of sanitary authorities to monitor environmental risks associated with Buruli ulcer.

The major antigenic membrane protein of "Candidatus Phytoplasma asteris" selectively interacts with ATP synthase and actin of leafhopper vectors.

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Luciana Galetto

Full Text Available Phytoplasmas, uncultivable phloem-limited phytopathogenic wall-less bacteria, represent a major threat to agriculture worldwide. They are transmitted in a persistent, propagative manner by phloem-sucking Hemipteran insects. Phytoplasma membrane proteins are in direct contact with hosts and are presumably involved in determining vector specificity. Such a role has been proposed for phytoplasma transmembrane proteins encoded by circular extrachromosomal elements, at least one of which is a plasmid. Little is known about the interactions between major phytoplasma antigenic membrane protein (Amp and insect vector proteins. The aims of our work were to identify vector proteins interacting with Amp and to investigate their role in transmission specificity. In controlled transmission experiments, four Hemipteran species were identified as vectors of "Candidatus Phytoplasma asteris", the chrysanthemum yellows phytoplasmas (CYP strain, and three others as non-vectors. Interactions between a labelled (recombinant CYP Amp and insect proteins were analysed by far Western blots and affinity chromatography. Amp interacted specifically with a few proteins from vector species only. Among Amp-binding vector proteins, actin and both the α and β subunits of ATP synthase were identified by mass spectrometry and Western blots. Immunofluorescence confocal microscopy and Western blots of plasma membrane and mitochondrial fractions confirmed the localisation of ATP synthase, generally known as a mitochondrial protein, in plasma membranes of midgut and salivary gland cells in the vector Euscelidius variegatus. The vector-specific interaction between phytoplasma Amp and insect ATP synthase is demonstrated for the first time, and this work also supports the hypothesis that host actin is involved in the internalization and intracellular motility of phytoplasmas within their vectors. Phytoplasma Amp is hypothesized to play a crucial role in insect transmission specificity.

Timing of host feeding drives rhythms in parasite replication

KAUST Repository

Prior, Kimberley F

2017-12-07

arena for studying host-parasite-vector coevolution and has broad implications for applied bioscience.

Folic acid conjugated mPEG-PEI600 as an efficient non-viral vector for targeted nucleic acid delivery.

Science.gov (United States)

Xu, Zhenhua; Jin, Jiefu; Siu, Leo K S; Yao, Hong; Sze, Johnny; Sun, Hongzhe; Kung, Hsiang-Fu; Poon, Wai Sang; Ng, Samuel S M; Lin, Marie C

2012-04-15

In this study we describe a novel polymer, mPPS-FA, synthesized as a potential gene transfer vector. To complete mPPS-FA, folic acid was conjugated to a backbone (named mPPS) consisting of a copolymer of methyl PEG-2000, PEI-600, and sebacoyl chloride. (1)H NMR, FT-IR, and UV spectroscopy were used to characterize the structure of mPPS-FA. It was revealed that mPPS-FA holds the ability to bind plasmid DNA yielding positively charged particles (polyplexes). Dynamic light scattering (DLS) and TEM techniques were used to study the size and morphology of the formed mPPS-FA/DNA nanocomplexes. The mPPS-FA/DNA nanoparticles exhibited low cytotoxicity as transfection of B16-F0, U87MG, CHO-1, and Ho-8910 cells produced >80% viability indicating low cytotoxicity of the polymer. The ability of mPPS-FA to deliver EGFP plasmid to melanoma B16-F0, U87, CHO-1, Ho-8910, and A549 cells was investigated in vitro as compared to the lipid-based transfection agent Lipofectamine2000 and Linear PEI 22 kDa (L-PEI 22 kDa). We found that mPPS-FA/DNA complexes yielded the highest GFP transfection efficiency in B16-F0, U87, CHO-1, and Ho-8910 cells, which all highly express folate receptors (FR), at an mPPS-FA/DNA ratio (w/w) of 15. Furthermore, the transfection of mPPS-FA/DNA complexes in CHO-1 cells could be competitively blocked by free folic acid molecules. In contrast, in low FR expressing A549 cells, mPPS-FA showed similar low transfection efficiency as mPPS. Taken together, mPPS-FA showed the highest efficiency in vitro and the potential to be developed as a nonviral gene carrier. Copyright © 2012 Elsevier B.V. All rights reserved.

Vectorization of agrochemicals: amino acid carriers are more efficient than sugar carriers to translocate phenylpyrrole conjugates in the Ricinus system.

Science.gov (United States)

Wu, Hanxiang; Marhadour, Sophie; Lei, Zhi-Wei; Yang, Wen; Marivingt-Mounir, Cécile; Bonnemain, Jean-Louis; Chollet, Jean-François

2018-05-01

Producing quality food in sufficient quantity while using less agrochemical inputs will be one of the great challenges of the twenty-first century. One way of achieving this goal is to greatly reduce the doses of plant protection compounds by improving the targeting of pests to eradicate. Therefore, we developed a vectorization strategy to confer phloem mobility to fenpiclonil, a contact fungicide from the phenylpyrrole family used as a model molecule. It consists in coupling the antifungal compound to an amino acid or a sugar, so that the resulting conjugates are handled by active nutrient transport systems. The method of click chemistry was used to synthesize three conjugates combining fenpiclonil to glucose or glutamic acid with a spacer containing a triazole ring. Systemicity tests with the Ricinus model have shown that the amino acid promoiety was clearly more favorable to phloem mobility than that of glucose. In addition, the transport of the amino acid conjugate is carrier mediated since the derivative of the L series was about five times more concentrated in the phloem sap than its counterpart of the D series. The systemicity of the L-derivative is pH dependent and almost completely inhibited by the protonophore carbonyl cyanide 3-chlorophenylhydrazone (CCCP). These data suggest that the phloem transport of the L-derivative is governed by a stereospecific amino acid carrier system energized by the proton motive force.

Does reservoir host mortality enhance transmission of West Nile virus?

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Foppa Ivo M

2007-05-01

Full Text Available Abstract Background Since its 1999 emergence in New York City, West Nile virus (WNV has become the most important and widespread cause of mosquito-transmitted disease in North America. Its sweeping spread from the Atlantic to the Pacific coast was accompanied by widespread mortality among wild birds, especially corvids. Only sporadic avian mortality had previously been associated with this infection in the Old World. Here, we examine the possibility that reservoir host mortality may intensify transmission, both by concentrating vector mosquitoes on remaining hosts and by preventing the accumulation of "herd immunity". Results Inspection of the Ross-Macdonald expression of the basic reproductive number (R0 suggests that this quantity may increase with reservoir host mortality. Computer simulation confirms this finding and indicates that the level of virulence is positively associated with the numbers of infectious mosquitoes by the end of the epizootic. The presence of reservoir incompetent hosts in even moderate numbers largely eliminated the transmission-enhancing effect of host mortality. Local host die-off may prevent mosquitoes to "waste" infectious blood meals on immune host and may thus facilitate perpetuation and spread of transmission. Conclusion Under certain conditions, host mortality may enhance transmission of WNV and similarly maintained arboviruses and thus facilitate their emergence and spread. The validity of the assumptions upon which this argument is built need to be empirically examined.

[Cloning and gene expression in lactic acid bacteria].

Science.gov (United States)

Bondarenko, V M; Beliavskaia, V A

2000-01-01

The possibility of using the genera Lactobacillus and Lactococcus as vector representatives is widely discussed at present. The prospects of the construction of recombinant bacteria are closely connected with the solution of a number of problems: the level of the transcription of cloned genes, the effectiveness of the translation of heterologous mRNA, the stability of protein with respect to bacterial intracellular proteases, the method by protein molecules leave the cell (by secretion or as the result of lysis). To prevent segregation instability, the construction of vector molecules on the basis of stable cryptic plasmids found in wild strains of lactic acid bacteria was proposed. High copying plasmids with low molecular weight were detected in L. plantarum and L. pentosus strains. Several plasmids with molecular weights of 1.7, 1.8 and 2.3 kb were isolated from bacterial cells to be used as the basis for the construction of vector molecules. Genes of chloramphenicol- and erythromycin-resistance from Staphylococcus aureus plasmids were used as marker genes ensuring cell transformation. The vector plasmids thus constructed exhibited high transformation activity in the electroporation of different strains, including L. casei, L. plantarum, L. acidophilus, L. fermentum and L. brevis which could be classified with the replicons of a wide circle of hosts. But the use of these plasmids was limited due to the risk of the uncontrolled dissemination of recombinant plasmids. L. acidophilus were also found to have strictly specific plasmids with good prospects of being used as the basis for the creation of vectors, incapable of dissemination. In addition to the search of strain-specific plasmids, incapable of uncontrolled gene transmission, the use of chromosome-integrated heterologous genes is recommended in cloning to ensure the maximum safety.

Effects of actonomycin D and ultraviolet irradiation on multiplication of brome mosaic virus in host and non-host cells

International Nuclear Information System (INIS)

Maekawa, K.; Furusawa, I.; Okuno, T.

1981-01-01

The modes of multiplication of brome mosaic virus (BMV) were compared in protoplasts isolated from host and non-host plants. BMV actively multiplied in the leaves and isolated mesophyll protoplasts of barley, a host of BMV. BMV multiplication in barley protoplasts was inhibited by addition of actinomycin D immediately after inoculation or by u.v. irradiation of the protoplasts before inoculation. In contrast, although BMV could not multiply in leaves of radish and turnip (non-hosts for BMV) it multiplied at a low level in protoplasts isolated from these two plant species. Moreover, u.v. irradiation, or the addition of actinomycin D, enhanced multiplication of BMV in radish and turnip protoplasts. These results suggest that (i) in the host cells replication of BMV is dependent on cellular metabolism of nucleic acid and protein, and (ii) in the non-host cells a substance(s) inhibitory to replication of BMV is synthesized. (author)

The distribution of potential West Nile virus vectors, Culex pipiens pipiens and Culex pipiens quinquefasciatus (Diptera: Culicidae), in Mexico City.

Science.gov (United States)

Diaz-Badillo, Alvaro; Bolling, Bethany G; Perez-Ramirez, Gerardo; Moore, Chester G; Martinez-Munoz, Jorge P; Padilla-Viveros, America A; Camacho-Nuez, Minerva; Diaz-Perez, Alfonso; Beaty, Barry J; Munoz, Maria de Lourdes

2011-05-09

Culex spp. mosquitoes are considered to be the most important vectors of West Nile virus (WNV) detected in at least 34 species of mosquitoes in the United States. In North America, Culex pipiens pipiens, Culex pipiens quinquefasciatus, and Culex tarsalis are all competent vectors of WNV, which is considered to be enzootic in the United States and has also been detected in equines and birds in many states of Mexico and in humans in Nuevo Leon. There is potential for WNV to be introduced into Mexico City by various means including infected mosquitoes on airplanes, migrating birds, ground transportation and infected humans. Little is known of the geographic distribution of Culex pipiens complex mosquitoes and hybrids in Mexico City. Culex pipiens pipiens preferentially feed on avian hosts; Culex pipiens quinquefasciatus have historically been considered to prefer mammalian hosts; and hybrids of these two species could theoretically serve as bridge vectors to transmit WNV from avian hosts to humans and other mammalian hosts. In order to address the potential of WNV being introduced into Mexico City, we have determined the identity and spatial distribution of Culex pipiens complex mosquitoes and their hybrids. Mosquito larvae collected from 103 sites throughout Mexico City during 2004-2005 were identified as Culex, Culiseta or Ochlerotatus by morphological analysis. Within the genus Culex, specimens were further identified as Culex tarsalis or as belonging to the Culex pipiens complex. Members of the Culex pipiens complex were separated by measuring the ratio of the dorsal and ventral arms (DV/D ratio) of the male genitalia and also by using diagnostic primers designed for the Ace.2 gene. Culex pipiens quinquefasciatus was the most abundant form collected. Important WNV vectors species, Cx. p. pipiens, Cx. p. quinquefasciatus and Cx. tarsalis, are all present in Mexico City. Hybrids of Cx. p. pipiens and Cx. p. quinquefasciatus were also collected and identified. The

The distribution of potential West Nile virus vectors, Culex pipiens pipiens and Culex pipiens quinquefasciatus (Diptera: Culicidae, in Mexico City

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Diaz-Perez Alfonso

2011-05-01

Full Text Available Abstract Background Culex spp. mosquitoes are considered to be the most important vectors of West Nile virus (WNV detected in at least 34 species of mosquitoes in the United States. In North America, Culex pipiens pipiens, Culex pipiens quinquefasciatus, and Culex tarsalis are all competent vectors of WNV, which is considered to be enzootic in the United States and has also been detected in equines and birds in many states of Mexico and in humans in Nuevo Leon. There is potential for WNV to be introduced into Mexico City by various means including infected mosquitoes on airplanes, migrating birds, ground transportation and infected humans. Little is known of the geographic distribution of Culex pipiens complex mosquitoes and hybrids in Mexico City. Culex pipiens pipiens preferentially feed on avian hosts; Culex pipiens quinquefasciatus have historically been considered to prefer mammalian hosts; and hybrids of these two species could theoretically serve as bridge vectors to transmit WNV from avian hosts to humans and other mammalian hosts. In order to address the potential of WNV being introduced into Mexico City, we have determined the identity and spatial distribution of Culex pipiens complex mosquitoes and their hybrids. Results Mosquito larvae collected from 103 sites throughout Mexico City during 2004-2005 were identified as Culex, Culiseta or Ochlerotatus by morphological analysis. Within the genus Culex, specimens were further identified as Culex tarsalis or as belonging to the Culex pipiens complex. Members of the Culex pipiens complex were separated by measuring the ratio of the dorsal and ventral arms (DV/D ratio of the male genitalia and also by using diagnostic primers designed for the Ace.2 gene. Culex pipiens quinquefasciatus was the most abundant form collected. Conclusions Important WNV vectors species, Cx. p. pipiens, Cx. p. quinquefasciatus and Cx. tarsalis, are all present in Mexico City. Hybrids of Cx. p. pipiens and Cx. p

Herpes simplex virus type 1 (HSV-1)-derived recombinant vectors for gene transfer and gene therapy.

Science.gov (United States)

Marconi, Peggy; Fraefel, Cornel; Epstein, Alberto L

2015-01-01

Herpes simplex virus type 1 (HSV-1 ) is a human pathogen whose lifestyle is based on a long-term dual interaction with the infected host, being able to establish both lytic and latent infections. The virus genome is a 153-kilobase pair (kbp) double-stranded DNA molecule encoding more than 80 genes. The interest of HSV-1 as gene transfer vector stems from its ability to infect many different cell types, both quiescent and proliferating cells, the very high packaging capacity of the virus capsid, the outstanding neurotropic adaptations that this virus has evolved, and the fact that it never integrates into the cellular chromosomes, thus avoiding the risk of insertional mutagenesis. Two types of vectors can be derived from HSV-1, recombinant vectors and amplicon vectors, and different methodologies have been developed to prepare large stocks of each type of vector. This chapter summarizes the approach most commonly used to prepare recombinant HSV-1 vectors through homologous recombination, either in eukaryotic cells or in bacteria.

Efficient gene transfer into nondividing cells by adeno-associated virus-based vectors.

Science.gov (United States)

Podsakoff, G; Wong, K K; Chatterjee, S

1994-09-01

Gene transfer vectors based on adeno-associated virus (AAV) are emerging as highly promising for use in human gene therapy by virtue of their characteristics of wide host range, high transduction efficiencies, and lack of cytopathogenicity. To better define the biology of AAV-mediated gene transfer, we tested the ability of an AAV vector to efficiently introduce transgenes into nonproliferating cell populations. Cells were induced into a nonproliferative state by treatment with the DNA synthesis inhibitors fluorodeoxyuridine and aphidicolin or by contact inhibition induced by confluence and serum starvation. Cells in logarithmic growth or DNA synthesis arrest were transduced with vCWR:beta gal, an AAV-based vector encoding beta-galactosidase under Rous sarcoma virus long terminal repeat promoter control. Under each condition tested, vCWR:beta Gal expression in nondividing cells was at least equivalent to that in actively proliferating cells, suggesting that mechanisms for virus attachment, nuclear transport, virion uncoating, and perhaps some limited second-strand synthesis of AAV vectors were present in nondividing cells. Southern hybridization analysis of vector sequences from cells transduced while in DNA synthetic arrest and expanded after release of the block confirmed ultimate integration of the vector genome into cellular chromosomal DNA. These findings may provide the basis for the use of AAV-based vectors for gene transfer into quiescent cell populations such as totipotent hematopoietic stem cells.

Within-host competition does not select for virulence in malaria parasites; studies with Plasmodium yoelii.

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Hussein M Abkallo

2015-02-01

Full Text Available In endemic areas with high transmission intensities, malaria infections are very often composed of multiple genetically distinct strains of malaria parasites. It has been hypothesised that this leads to intra-host competition, in which parasite strains compete for resources such as space and nutrients. This competition may have repercussions for the host, the parasite, and the vector in terms of disease severity, vector fitness, and parasite transmission potential and fitness. It has also been argued that within-host competition could lead to selection for more virulent parasites. Here we use the rodent malaria parasite Plasmodium yoelii to assess the consequences of mixed strain infections on disease severity and parasite fitness. Three isogenic strains with dramatically different growth rates (and hence virulence were maintained in mice in single infections or in mixed strain infections with a genetically distinct strain. We compared the virulence (defined as harm to the mammalian host of mixed strain infections with that of single infections, and assessed whether competition impacted on parasite fitness, assessed by transmission potential. We found that mixed infections were associated with a higher degree of disease severity and a prolonged infection time. In the mixed infections, the strain with the slower growth rate was often responsible for the competitive exclusion of the faster growing strain, presumably through host immune-mediated mechanisms. Importantly, and in contrast to previous work conducted with Plasmodium chabaudi, we found no correlation between parasite virulence and transmission potential to mosquitoes, suggesting that within-host competition would not drive the evolution of parasite virulence in P. yoelii.

Plasmid Vectors for Xylella fastidiosa Utilizing a Toxin-Antitoxin System for Stability in the Absence of Antibiotic Selection.

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Burbank, Lindsey P; Stenger, Drake C

2016-08-01

The phytopathogen Xylella fastidiosa causes disease in a variety of important crop and landscape plants. Functional genetic studies have led to a broader understanding of virulence mechanisms used by this pathogen in the grapevine host. Plasmid shuttle vectors are important tools in studies of bacterial genetics but there are only a limited number of plasmid vectors available that replicate in X. fastidiosa, and even fewer that are retained without antibiotic selection. Two plasmids are described here that show stable replication in X. fastidiosa and are effective for gene complementation both in vitro and in planta. Plasmid maintenance is facilitated by incorporation of the PemI/PemK plasmid addiction system, consisting of PemK, an endoribonuclease toxin, and its cognate antitoxin, PemI. Vector pXf20pemIK utilizes a native X. fastidiosa replication origin as well as a high-copy-number pUC origin for propagation in Escherichia coli cloning strains. Broad-host-range vector pBBR5pemIK is a medium- to low-copy-number plasmid based on the pBBR1 backbone. Both plasmids are maintained for extended periods of time in the absence of antibiotic selection, as well as up to 14 weeks in grapevine, without affecting bacterial fitness. These plasmids present an alternative to traditional complementation and expression vectors which rely on antibiotic selection for plasmid retention.

Genetically engineering adenoviral vectors for gene therapy.

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Coughlan, Lynda

2014-01-01

Adenoviral (Ad) vectors are commonly used for various gene therapy applications. Significant advances in the genetic engineering of Ad vectors in recent years has highlighted their potential for the treatment of metastatic disease. There are several methods to genetically modify the Ad genome to incorporate retargeting peptides which will redirect the natural tropism of the viruses, including homologous recombination in bacteria or yeast. However, homologous recombination in yeast is highly efficient and can be achieved without the need for extensive cloning strategies. In addition, the method does not rely on the presence of unique restriction sites within the Ad genome and the reagents required for this method are widely available and inexpensive. Large plasmids containing the entire adenoviral genome (~36 kbp) can be modified within Saccharomyces cerevisiae yeast and genomes easily rescued in Escherichia coli hosts for analysis or amplification. A method for two-step homologous recombination in yeast is described in this chapter.

Poxvirus-vectored vaccines for rabies--a review.

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Weyer, Jacqueline; Rupprecht, Charles E; Nel, Louis H

2009-11-27

Oral rabies vaccination of target reservoir species has proved to be one of the pillars of successful rabies elimination programs. The use of live attenuated rabies virus vaccines has been extensive but several limitations hamper its future use. A recombinant vaccinia-rabies vaccine has also been successfully used for the oral vaccination of several species. Nevertheless, its lack of efficacy in certain important rabies reservoirs and concerns on the use of this potent live virus as vaccine carrier (vector) impair the expansion of its use for new target species and new areas. Several attenuated and host-restricted poxvirus alternatives, which supposedly offer enhanced safety, have been investigated. Once again, efficacy in certain target species and innocuity through the oral route remain major limitations of these vaccines. Alternative recombinant vaccines using adenovirus as an antigen delivery vector have been extensively investigated and may provide an important addition to the currently available oral rabies vaccine repertoire, but are not the primary subject of this review.

Multicompartment vectors as novel drug delivery systems: selective activation of Tγδ lymphocytes after zoledronic acid delivery.

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Agrati, Chiara; Marianecci, Carlotta; Sennato, Simona; Carafa, Maria; Bordoni, Veronica; Cimini, Eleonora; Tempestilli, Massimo; Pucillo, Leopoldo P; Turchi, Federica; Martini, Federico; Borioni, Giorgio; Bordi, Federico

2011-04-01

Multicompartment nanoscopic carriers can be easily assembled by inducing the aggregation of anionic "hybrid" niosomes by means of cationic biocompatible polyelectrolytes. The resulting vesicle clusters, whose size and overall net charge can be easily controlled by varying the polyelectrolyte-to-particle charge ratio, show an interesting potential for multidrug delivery. In this article we provide strong evidence for their effective use in vitro as multicompartment vectors selectively directed toward monocyte/macrophage cells, showing that the monocyte/macrophage-mediated activation of Tγδ lymphocytes induced by zoledronic acid is enhanced by a factor 10(3) when the zoledronic acid is intracellularly delivered through these carriers. Furthermore, the multicompartment ɛ-polylysine niosome clusters, with their intrinsic selectivity toward macrophages, appear particularly suitable for implementing therapeutic strategies against chronically infected macrophages. ɛ-polylysine niosome clusters, with their intrinsic selectivity toward macrophages, offer the potential for multidrug delivery. The effectiveness of aminobisphosphonate zoledronate is demonstrated to enhance the recruitment of Tγδ lymphocytes by macrophages by 2 orders of magnitude, suggesting a new therapeutic strategy for addressing pathologies featuring chronically infected macrophages. Copyright © 2011 Elsevier Inc. All rights reserved.

Population structure of the soft tick Ornithodoros maritimus and its associated infectious agents within a colony of its seabird host Larus michahellis

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Marlene Dupraz

2017-08-01

Full Text Available The epidemiology of vector-borne zoonoses depends on the movement of both hosts and vectors, which can differ greatly in intensity across spatial scales. Because of their life history traits and small size, vector dispersal may be frequent, but limited in distance. However, little information is available on vector movement patterns at local spatial scales, and particularly for ticks, transmitting the greatest diversity of recognized infectious agents. To test the degree to which ticks can disperse and disseminate pathogens at local scales, we investigated the temporal dynamics and population structure of the soft tick Ornithodoros maritimus within a colony of its seabird host, the Yellow-legged gull Larus michahellis. Ticks were repeatedly sampled at a series of nests during the host breeding season. In half of the nests, ticks were collected (removal sampling, in the other half, ticks were counted and returned to the nest. A subsample of ticks was screened for known bacteria, viruses and parasites using a high throughput real-time PCR system to examine their distribution within the colony. The results indicate a temporal dynamic in the presence of tick life stages over the season, with the simultaneous appearance of juvenile ticks and hatched chicks, but no among-nest spatial structure in tick abundance. Removal sampling significantly reduced tick numbers, but only from the fourth visit onward. Seven bacterial isolates, one parasite species and one viral isolate were detected but no spatial structure in their presence within the colony was found. These results suggest weak isolation among nests and that tick dispersal is likely frequent enough to quickly recolonize locally-emptied patches and disseminate pathogens across the colony. Vector-mediated movements at local scales may therefore play a key role in pathogen emergence and needs to be considered in conjunction with host movements for predicting pathogen circulation and for establishing

Virulence of a malaria parasite, Plasmodium mexicanum, for its sand fly vectors, Lutzomyia vexator and Lutzomyia stewarti (Diptera: Psychodidae).

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Schall, Jos J

2011-11-01

Evolutionary theory predicts that virulence of parasites for mobile vector insects will be low for natural parasite-host associations that have coevolved. I determined virulence of the malaria parasite of lizards, Plasmodium mexicanum, for its vectors, two species of sand fly (Diptera: Psychodidae), Lutzomyia vexator (Coquillett 1907) and Lutzomyia stewarti (Mangabeira Fo & Galindo 1944), by measuring several life history traits. Developmental rate from egg to eclosion differed for the two species when noninfected. For both sand fly species, developmental rate for each stage (egg to larval hatching, larval period, pupal period) and life span were not altered by infection. Infected sand flies, however, produced fewer eggs. This reduction in fecundity may be a result of lower quality of the blood meal taken from infected lizards (lower concentration of hemoglobin). This report is the first measure of virulence of Plasmodium for an insect vector other than a mosquito and concords with both expectations of theory and previous studies on natural parasite-host associations that revealed low virulence.

Use of vectors in sequence analysis.

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Ishikawa, T; Yamamoto, K; Yoshikura, H

1987-10-01

Applications of the vector diagram, a new type of representation of protein structure, in homology search of various proteins including oncogene products are presented. The method takes account of various kinds of information concerning the properties of amino acids, such as Chou and Fasman's probability data. The method can detect conformational similarities of proteins which may not be detected by the conventional programs.

Parallel computation for distributed parameter system-from vector processors to Adena computer

Energy Technology Data Exchange (ETDEWEB)

Nogi, T

1983-04-01

Research on advanced parallel hardware and software architectures for very high-speed computation deserves and needs more support and attention to fulfil its promise. Novel architectures for parallel processing are being made ready. Architectures for parallel processing can be roughly divided into two groups. One is a vector processor in which a single central processing unit involves multiple vector-arithmetic registers. The other is a processor array in which slave processors are connected to a host processor to perform parallel computation. In this review, the concept and data structure of the Adena (alternating-direction edition nexus array) architecture, which is conformable to distributed-parameter simulation algorithms, are described. 5 references.

Identification of Blood Meals from Potential Arbovirus Mosquito Vectors in the Peruvian Amazon Basin.

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Palermo, Pedro M; Aguilar, Patricia V; Sanchez, Juan F; Zorrilla, Víctor; Flores-Mendoza, Carmen; Huayanay, Anibal; Guevara, Carolina; Lescano, Andrés G; Halsey, Eric S

2016-11-02

The transmission dynamics of many arboviruses in the Amazon Basin region have not been fully elucidated, including the vectors and natural reservoir hosts. Identification of blood meal sources in field-caught mosquitoes could yield information for identifying potential arbovirus vertebrate hosts. We identified blood meal sources in 131 mosquitoes collected from areas endemic for arboviruses in the Peruvian Department of Loreto by sequencing polymerase chain reaction amplicons of the cytochrome b gene. Psorophora (Janthinosoma) albigenu, Psorophora (Grabhamia) cingulata, Mansonia humeralis, Anopheles oswaldoi s.l., and Anopheles benarrochi s.l. had mainly anthropophilic feeding preferences; Aedes (Ochlerotatus) serratus, and Aedes (Ochlerotatus) fulvus had feeding preferences for peridomestic animals; and Culex (Melanoconion) spp. fed on a variety of vertebrates, mainly rodents (spiny rats), birds, and amphibians. On the basis of these feeding preferences, many mosquitoes could be considered as potential enzootic and bridge arbovirus vectors in the Amazon Basin of Peru. © The American Society of Tropical Medicine and Hygiene.

A Deep Insight into the Sialome of Rhodnius neglectus, a Vector of Chagas Disease.

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Paula Beatriz Santiago

2016-04-01

Full Text Available Triatomines are hematophagous insects that act as vectors of Chagas disease. Rhodnius neglectus is one of these kissing bugs found, contributing to the transmission of this American trypanosomiasis. The saliva of hematophagous arthropods contains bioactive molecules responsible for counteracting host haemostatic, inflammatory, and immune responses.Next generation sequencing and mass spectrometry-based protein identification were performed to investigate the content of triatomine R. neglectus saliva. We deposited 4,230 coding DNA sequences (CDS in GenBank. A set of 636 CDS of proteins of putative secretory nature was extracted from the assembled reads, 73 of them confirmed by proteomic analysis. The sialome of R. neglectus was characterized and serine protease transcripts detected. The presence of ubiquitous protein families was revealed, including lipocalins, serine protease inhibitors, and antigen-5. Metalloproteases, disintegrins, and odorant binding protein families were less abundant.The data presented improve our understanding of hematophagous arthropod sialomes, and aid in understanding hematophagy and the complex interplay among vectors and their vertebrate hosts.

Diverse host feeding on nesting birds may limit early-season West Nile virus amplification.

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Egizi, Andrea M; Farajollahi, Ary; Fonseca, Dina M

2014-06-01

Arboviral activity tracks vector availability, which in temperate regions means that transmission ceases during the winter and must be restarted each spring. In the northeastern United States, Culex restuans Theobald resumes its activity earlier than Culex pipiens L. and is thought to be important in restarting West Nile virus (WNV) transmission. Its role in WNV amplification, however, is unclear, because viral levels commonly remain low until the rise of Cx. pipiens later in the season. Because a vector's feeding habits can reveal key information about disease transmission, we identified early-season (April-June) blood meals from Cx. restuans collected throughout New Jersey, and compared them to published datasets from later in the season and also from other parts of the country. We found significantly higher avian diversity, including poor WNV hosts, and fewer blood meals derived from American Robins (17% versus over 40% found in later season). Critically, we identified blood meals from significantly more female than male birds in species where females are the incubating sex, suggesting that Cx. restuans is able to feed on such a wide variety of hosts in early spring because incubating birds are easy targets. Because WNV amplification depends on virus consistently reaching competent hosts, our results indicate that Cx. restuans is unlikely to be an amplifying vector of WNV in the early season. As the season progresses, however, changes in the availability of nesting birds may make it just as capable as Cx. pipiens, although at somewhat lower abundance as the summer progresses.

The specific transmission of Grapevine fanleaf virus by its nematode vector Xiphinema index is solely determined by the viral coat protein

International Nuclear Information System (INIS)

Andret-Link, Peggy; Schmitt-Keichinger, Corinne; Demangeat, Gerard; Komar, Veronique; Fuchs, Marc

2004-01-01

The viral determinants involved in the specific transmission of Grapevine fanleaf virus (GFLV) by its nematode vector Xiphinema index are located within the 513 C-terminal residues of the RNA2-encoded polyprotein, that is, the 9 C-terminal amino acids of the movement protein (2B MP ) and contiguous 504 amino acids of the coat protein (2C CP ) [Virology 291 (2001) 161]. To further delineate the viral determinants responsible for the specific spread, the four amino acids that are different within the 9 C-terminal 2B MP residues between GFLV and Arabis mosaic virus (ArMV), another nepovirus which is transmitted by Xiphinema diversicaudatum but not by X. index, were subjected to mutational analysis. Of the recombinant viruses derived from transcripts of GFLV RNA1 and RNA2 mutants that systemically infected herbaceous host plants, all with the 2C CP of GFLV were transmitted by X. index unlike none with the 2C CP of ArMV, regardless of the mutations within the 2B MP C-terminus. These results demonstrate that the coat protein is the sole viral determinant for the specific spread of GFLV by X. index

Induction of Immune Tolerance to Foreign Protein via Adeno-Associated Viral Vector Gene Transfer in Mid-Gestation Fetal Sheep

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Davey, Marcus G.; Riley, John S.; Andrews, Abigail; Tyminski, Alec; Limberis, Maria; Pogoriler, Jennifer E.; Partridge, Emily; Olive, Aliza; Hedrick, Holly L.; Flake, Alan W.; Peranteau, William H.

2017-01-01

A major limitation to adeno-associated virus (AAV) gene therapy is the generation of host immune responses to viral vector antigens and the transgene product. The ability to induce immune tolerance to foreign protein has the potential to overcome this host immunity. Acquisition and maintenance of tolerance to viral vector antigens and transgene products may also permit repeat administration thereby enhancing therapeutic efficacy. In utero gene transfer (IUGT) takes advantage of the immunologic immaturity of the fetus to induce immune tolerance to foreign antigens. In this large animal study, in utero administration of AAV6.2, AAV8 and AAV9 expressing green fluorescent protein (GFP) to ~60 day fetal sheep (term: ~150 days) was performed. Transgene expression and postnatal immune tolerance to GFP and viral antigens were assessed. We demonstrate 1) hepatic expression of GFP 1 month following in utero administration of AAV6.2.GFP and AAV8.GFP, 2) in utero recipients of either AAV6.2.GFP or AAV8.GFP fail to mount an anti-GFP antibody response following postnatal GFP challenge and lack inflammatory cellular infiltrates at the intramuscular site of immunization, 3) a serotype specific anti-AAV neutralizing antibody response is elicited following postnatal challenge of in utero recipients of AAV6.2 or AAV8 with the corresponding AAV serotype, and 4) durable hepatic GFP expression was observed up to 6 months after birth in recipients of AAV8.GFP but expression was lost between 1 and 6 months of age in recipients of AAV6.2.GFP. The current study demonstrates, in a preclinical large animal model, the potential of IUGT to achieve host immune tolerance to the viral vector transgene product but also suggests that a single exposure to the vector capsid proteins at the time of IUGT is inadequate to induce tolerance to viral vector antigens. PMID:28141818

Broader prevalence of Wolbachia in insects including potential human disease vectors.

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de Oliveira, C D; Gonçalves, D S; Baton, L A; Shimabukuro, P H F; Carvalho, F D; Moreira, L A

2015-06-01

Wolbachia are intracellular, maternally transmitted bacteria considered the most abundant endosymbionts found in arthropods. They reproductively manipulate their host in order to increase their chances of being transmitted to the offspring, and currently are being used as a tool to control vector-borne diseases. Studies on distribution of Wolbachia among its arthropod hosts are important both for better understanding why this bacterium is so common, as well as for its potential use as a biological control agent. Here, we studied the incidence of Wolbachia in a broad range of insect species, collected from different regions of Brazil, using three genetic markers (16S rRNA, wsp and ftsZ), which varied in terms of their sensitivity to detect this bacterium. The overall incidence of Wolbachia among species belonging to 58 families and 14 orders was 61.9%. The most common positive insect orders were Coleoptera, Diptera, Hemiptera and Hymenoptera, with Diptera and Hemiptera having the highest numbers of Wolbachia-positive families. They included potential human disease vectors whose infection status has never been reported before. Our study further shows the importance of using quantitative polymerase chain reaction for high-throughput and sensitive Wolbachia screening.

The ecological foundations of transmission potential and vector-borne disease in urban landscapes.

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LaDeau, Shannon L; Allan, Brian F; Leisnham, Paul T; Levy, Michael Z

2015-07-01

Urban transmission of arthropod-vectored disease has increased in recent decades. Understanding and managing transmission potential in urban landscapes requires integration of sociological and ecological processes that regulate vector population dynamics, feeding behavior, and vector-pathogen interactions in these unique ecosystems. Vectorial capacity is a key metric for generating predictive understanding about transmission potential in systems with obligate vector transmission. This review evaluates how urban conditions, specifically habitat suitability and local temperature regimes, and the heterogeneity of urban landscapes can influence the biologically-relevant parameters that define vectorial capacity: vector density, survivorship, biting rate, extrinsic incubation period, and vector competence.Urban landscapes represent unique mosaics of habitat. Incidence of vector-borne disease in urban host populations is rarely, if ever, evenly distributed across an urban area. The persistence and quality of vector habitat can vary significantly across socio-economic boundaries to influence vector species composition and abundance, often generating socio-economically distinct gradients of transmission potential across neighborhoods.Urban regions often experience unique temperature regimes, broadly termed urban heat islands (UHI). Arthropod vectors are ectothermic organisms and their growth, survival, and behavior are highly sensitive to environmental temperatures. Vector response to UHI conditions is dependent on regional temperature profiles relative to the vector's thermal performance range. In temperate climates UHI can facilitate increased vector development rates while having countervailing influence on survival and feeding behavior. Understanding how urban heat island (UHI) conditions alter thermal and moisture constraints across the vector life cycle to influence transmission processes is an important direction for both empirical and modeling research.There remain

A chitinase is required for Xylella fastidiosa colonization of its insect and plant hosts.

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Labroussaa, Fabien; Ionescu, Michael; Zeilinger, Adam R; Lindow, Steven E; Almeida, Rodrigo P P

2017-04-01

Xylella fastidiosa colonizes the xylem network of host plant species as well as the foregut of its required insect vectors to ensure efficient propagation. Disease management strategies remain inefficient due to a limited comprehension of the mechanisms governing both insect and plant colonization. It was previously shown that X. fastidiosa has a functional chitinase (ChiA), and that chitin likely serves as a carbon source for this bacterium. We expand on that research, showing that a chiA mutant strain is unable to grow on chitin as the sole carbon source. Quantitative PCR assays allowed us to detect bacterial cells in the foregut of vectors after pathogen acquisition; populations of the wild-type and complemented mutant strain were both significantly larger than the chiA mutant strain 10 days, but not 3 days, post acquisition. These results indicate that adhesion of the chiA mutant strain to vectors may not be impaired, but that cell multiplication is limited. The mutant was also affected in its transmission by vectors to plants. In addition, the chiA mutant strain was unable to colonize host plants, suggesting that the enzyme has other substrates associated with plant colonization. Lastly, ChiA requires other X. fastidiosa protein(s) for its in vitro chitinolytic activity. The observation that the chiA mutant strain is not able to colonize plants warrants future attention to be paid to the substrates for this enzyme.

Phenolic acid changes during Orobanche parasitism on faba bean ...

African Journals Online (AJOL)

The present work is intended to provide further information on broomrape parasitism based on phenolic acid changes in either the host plant(s) or in each of the host and the parasite in the host-parasite system. Detection of phenolic acids was carried out using high performance liquid chromatography (HPLC) in the host ...

Producing biofuels using polyketide synthases

Science.gov (United States)

Katz, Leonard; Fortman, Jeffrey L; Keasling, Jay D

2013-04-16

The present invention provides for a non-naturally occurring polyketide synthase (PKS) capable of synthesizing a carboxylic acid or a lactone, and a composition such that a carboxylic acid or lactone is included. The carboxylic acid or lactone, or derivative thereof, is useful as a biofuel. The present invention also provides for a recombinant nucleic acid or vector that encodes such a PKS, and host cells which also have such a recombinant nucleic acid or vector. The present invention also provides for a method of producing such carboxylic acids or lactones using such a PKS.

Evidence That Speciation of Oxovanadium Complexes Does Not Solely Account for Inhibition of Leishmania Acid Phosphatases

Science.gov (United States)

Dorsey, Benjamin M.; McLauchlan, Craig C.; Jones, Marjorie A.

2018-01-01

Leishmaniasis is an endemic disease affecting a diverse spectra of populations, with 1.6 million new cases reported each year. Current treatment options are costly and have harsh side effects. New therapeutic options that have been previously identified, but still underappreciated as potential pharmaceutical targets, are Leishmania secreted acid phosphatases (SAP). These acid phosphatases, which are reported to play a role in the survival of the parasite in the sand fly vector, and in homing to the host macrophage, are inhibited by orthovanadate and decavanadate. Here, we use L. tarentolae to further evaluate these inhibitors. Using enzyme assays, and UV-visible spectroscopy, we investigate which oxovanadium starting material (orthovanadate or decavanadate) is a better inhibitor of L. tarentolae secreted acid phosphatase activity in vitro at the same total moles of vanadium. Considering speciation and total vanadium concentration, decavanadate is a consistently better inhibitor of SAP in our conditions, especially at low substrate:inhibitor ratios. PMID:29707535

Evidence that Speciation of Oxovanadium Complexes does not Solely Account for Inhibition of Leishmania Acid Phosphatases

Science.gov (United States)

Dorsey, Benjamin M.; McLauchlan, Craig C.; Jones, Marjorie A.

2018-04-01

Leishmaniasis is an endemic disease affecting a diverse spectra of populations, with 1.6 million new cases reported each year. Current treatment options are costly and have harsh side effects. New therapeutic options that have been previously identified, but still underappreciated as potential pharmaceutical targets, are Leishmania secreted acid phosphatases (SAP). These acid phosphatases, which are reported to play a role in the survival of the parasite in the sand fly vector, and in homing to the host macrophage, are inhibited by orthovanadate and decavanadate. Here, we use L. tarentolae to further evaluate these inhibitors. Using enzyme assays, and UV-visible spectroscopy, we investigate which oxovanadium starting material (orthovanadate or decavanadate) is a better inhibitor of L. tarentolae secreted acid phosphatase activity in vitro at the same total moles of vanadium. Considering speciation and total vanadium concentration, decavanadate is a consistently better inhibitor of SAP in our conditions, especially at low substrate:inhibitor ratios.

The vaginal microbiota, host defence and reproductive physiology.

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Smith, Steven B; Ravel, Jacques

2017-01-15

The interaction between the human host and the vaginal microbiota is highly dynamic. Major changes in the vaginal physiology and microbiota over a woman's lifetime are largely shaped by transitional periods such as puberty, menopause and pregnancy, while daily fluctuations in microbial composition observed through culture-independent studies are more likely to be the results of daily life activities and behaviours. The vaginal microbiota of reproductive-aged women is largely made up of at least five different community state types. Four of these community state types are dominated by lactic-acid producing Lactobacillus spp. while the fifth is commonly composed of anaerobes and strict anaerobes and is sometimes associated with vaginal symptoms. The production of lactic acid has been associated with contributing to the overall health of the vagina due to its direct and indirect effects on pathogens and host defence. Some species associated with non-Lactobacillus vaginal microbiota may trigger immune responses as well as degrade the host mucosa, processes that ultimately increase susceptibility to infections and contribute to negative reproductive outcomes such as infertility and preterm birth. Further studies are needed to better understand the functional underpinnings of how the vaginal microbiota affect host physiology but also how host physiology affects the vaginal microbiota. Understanding this fine-tuned interaction is key to maintaining women's reproductive health. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

The vaginal microbiota, host defence and reproductive physiology

Science.gov (United States)

Smith, Steven B

2016-01-01

Abstract The interaction between the human host and the vaginal microbiota is highly dynamic. Major changes in the vaginal physiology and microbiota over a woman's lifetime are largely shaped by transitional periods such as puberty, menopause and pregnancy, while daily fluctuations in microbial composition observed through culture‐independent studies are more likely to be the results of daily life activities and behaviours. The vaginal microbiota of reproductive‐aged women is largely made up of at least five different community state types. Four of these community state types are dominated by lactic‐acid producing Lactobacillus spp. while the fifth is commonly composed of anaerobes and strict anaerobes and is sometimes associated with vaginal symptoms. The production of lactic acid has been associated with contributing to the overall health of the vagina due to its direct and indirect effects on pathogens and host defence. Some species associated with non‐Lactobacillus vaginal microbiota may trigger immune responses as well as degrade the host mucosa, processes that ultimately increase susceptibility to infections and contribute to negative reproductive outcomes such as infertility and preterm birth. Further studies are needed to better understand the functional underpinnings of how the vaginal microbiota affect host physiology but also how host physiology affects the vaginal microbiota. Understanding this fine‐tuned interaction is key to maintaining women's reproductive health. PMID:27373840

Biology of the Huanglongbing vector Diaphorina citri (Hemiptera: Liviidae) on different host plants.

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Alves, G R; Diniz, A J F; Parra, J R P

2014-04-01

Although many studies have been conducted on the development and reproductive potential of Diaphorina citri Kuwayama, 1908 (Hemiptera: Liviidae) in different host species, few have evaluated these parameters on different varieties of the same host species. This study evaluated the influence of five commercial varieties of citrus (Citrus spp. L.)--Hamlin, Natal, Pêra, Ponkan, and Valencia-and orange jasmine [Murraya exotica (L.) Jack] on the development of D. citri. Survival rates for the egg stage were highest on orange jasmine (85.7%) and on Valencia (83.3%). The lowest viability of the nymphal stage was also observed on Hamlin, averaging 57.4%. Values for total viability ranged from 65.9 to 32.6%, and were highest on Valencia. The longest egg-adult development time was on Natal, with a mean of 18.4 d; the shortest total development time was on orange jasmine, with a mean of 17.3 d. Based on the fertility life table, the net reproductive rate (Ro) of D. citri was 2.5 times higher when reared on Valencia than on Hamlin. The other parameters (duration of each generation [T], finite rate of increase [lambda], and innate capacity to increase in number [r(m)]) also demonstrated that Valencia is best suited to this insect. The results obtained for the biological parameters and the fertility life table indicate that Valencia and orange jasmine were the most suitable hosts, whereas Hamlin was least suitable for the development of D. citri. These results provide information for the installation of new citrus groves, especially in the choice of varieties to be planted and the location of different varieties within the groves, with a view toward the management of Huanglongbing or HLB.

Host range expansion and increased damage potential of Euwallacea nr. fornicatus (Coleoptera: Curculionidae) in Florida

Science.gov (United States)

Ambrosia beetles in the Euwallacea nr. fornicatus complex (Coleoptera: Curculionidae) vector Fusarium spp. fungi pathogenic to susceptible hosts, including avocado. The Florida avocado production area in Miami-Dade County was surveyed for E. nr. fornicatus upon observations of initial damage in 2016...

Host-pathogen interactions and genome evolution in two generalist and specialist microsporidian pathogens of mosquitoes

Science.gov (United States)

The adaptation of two distantly related microsporidia to their mosquito hosts was investigated. Edhazardia aedis is a specialist pathogen that infects Aedes aegypti, the main vector of dengue and yellow fever arboviruses. Vavraia culicis is a generalist pathogen of several insects including Anophele...

Critical behavior in a stochastic model of vector mediated epidemics

Science.gov (United States)

Alfinito, E.; Beccaria, M.; Macorini, G.

2016-06-01

The extreme vulnerability of humans to new and old pathogens is constantly highlighted by unbound outbreaks of epidemics. This vulnerability is both direct, producing illness in humans (dengue, malaria), and also indirect, affecting its supplies (bird and swine flu, Pierce disease, and olive quick decline syndrome). In most cases, the pathogens responsible for an illness spread through vectors. In general, disease evolution may be an uncontrollable propagation or a transient outbreak with limited diffusion. This depends on the physiological parameters of hosts and vectors (susceptibility to the illness, virulence, chronicity of the disease, lifetime of the vectors, etc.). In this perspective and with these motivations, we analyzed a stochastic lattice model able to capture the critical behavior of such epidemics over a limited time horizon and with a finite amount of resources. The model exhibits a critical line of transition that separates spreading and non-spreading phases. The critical line is studied with new analytical methods and direct simulations. Critical exponents are found to be the same as those of dynamical percolation.

Vector analysis

CERN Document Server

Newell, Homer E

2006-01-01

When employed with skill and understanding, vector analysis can be a practical and powerful tool. This text develops the algebra and calculus of vectors in a manner useful to physicists and engineers. Numerous exercises (with answers) not only provide practice in manipulation but also help establish students' physical and geometric intuition in regard to vectors and vector concepts.Part I, the basic portion of the text, consists of a thorough treatment of vector algebra and the vector calculus. Part II presents the illustrative matter, demonstrating applications to kinematics, mechanics, and e

Equine arteritis virus is delivered to an acidic compartment of host cells via clathrin-dependent endocytosis

International Nuclear Information System (INIS)

Nitschke, Matthias; Korte, Thomas; Tielesch, Claudia; Ter-Avetisyan, Gohar; Tuennemann, Gisela; Cardoso, M. Cristina; Veit, Michael; Herrmann, Andreas

2008-01-01

Equine arteritis virus (EAV) is an enveloped, positive-stranded RNA virus belonging to the family Arteriviridae. Infection by EAV requires the release of the viral genome by fusion with the respective target membrane of the host cell. We have investigated the entry pathway of EAV into Baby Hamster Kindey cells (BHK). Infection of cells assessed by the plaque reduction assay was strongly inhibited by substances which interfere with clathrin-dependent endocytosis and by lysosomotropic compounds. Furthermore, infection of BHK cells was suppressed when clathrin-dependent endocytosis was inhibited by expression of antisense RNA of the clathrin-heavy chain before infection. These results strongly suggest that EAV is taken up via clathrin-dependent endocytosis and is delivered to acidic endosomal compartments

Molecular recognition: Comparative study of a tunable host-guest system by using a fluorescent model system and collision-induced dissociation mass spectrometry on dendrimers

DEFF Research Database (Denmark)

Pittelkow, M.; Nielsen, C.B.; Broeren, A.C.

2005-01-01

Host-guest interactions between the periphery of adamantylurea-functionalized dendrimers (host) and ureido acetic acid derivatives (guest) were shown to be specific, strong and spatially well-defined. The binding becomes stronger when using phosphonic or sulfonic acid derivatives. In the present...... work we have quantified the binding constants for the host-guest interactions between two different host motifs and six different guest molecules. The host molecules, which resemble the periphery of a poly(propylene imine) dendrimer, have been fitted with an anthracene-based fluorescent probe. The two...... host motifs differ in terms of the length of the spacer between a tertiary amine and two ureido functionalities. The guest molecules all contain an acidic moiety (either a carboxylic acid, a phosphonic acid, or a sulfonic acid) and three of them also contain an ureido moiety capable of forming multiple...

Fatty acid composition of bacteria associated with the toxic dinoflagellate Ostreopsis lenticularis and with Caribbean Palythoa species.

Science.gov (United States)

Carballeira, N M; Emiliano, A; Sostre, A; Restituyo, J A; González, I M; Colón, G M; Tosteson, C G; Tosteson, T R

1998-06-01

The fatty acid composition of a Pseudomonas sp. (Alteromonas) and its host, the dinoflagellate Ostreopsis lenticularis, vectors in ciguatera fish poisoning, has been studied. The major fatty acids in O. lenticularis were 16:0, 20:5n-3, and 22:6n-3, but 18:2n-6, 18:3n-3, and 18:n-3 were also identified. In contrast to other dinoflagellates, 1 8:5n-3 was not detected in O. lenticularis. Even-chain fatty acids such as 9-16:1, 11-18:1, and 13-20:1 predominated in the Pseudomonas sp. from O. lenticularis, but 1 6-20% of (E)-11-methyl-12-octadecenoic acid was also identified. The chirality of the latter was confirmed by total synthesis (28% overall yield) starting from oxacyclotridecan-2-one. The fatty acid compositions of two other Pseudomonas species, from the palytoxin-producing zoanthids Palythoa mamillosa and P. caribdea, were also studied and were similar to that of the Pseudomonas sp. from O. lenticularis. The possibility of using some of these fatty acids as chemotaxonomic lipids in identifying marine animals that consume toxic dinoflagellates or zoanthids is discussed.

Vector-Tensor and Vector-Vector Decay Amplitude Analysis of B0→φK*0

International Nuclear Information System (INIS)

Aubert, B.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Tisserand, V.; Zghiche, A.; Grauges, E.; Palano, A.; Chen, J. C.; Qi, N. D.; Rong, G.; Wang, P.; Zhu, Y. S.; Eigen, G.; Ofte, I.; Stugu, B.; Abrams, G. S.

2007-01-01

We perform an amplitude analysis of the decays B 0 →φK 2 * (1430) 0 , φK * (892) 0 , and φ(Kπ) S-wave 0 with a sample of about 384x10 6 BB pairs recorded with the BABAR detector. The fractions of longitudinal polarization f L of the vector-tensor and vector-vector decay modes are measured to be 0.853 -0.069 +0.061 ±0.036 and 0.506±0.040±0.015, respectively. Overall, twelve parameters are measured for the vector-vector decay and seven parameters for the vector-tensor decay, including the branching fractions and parameters sensitive to CP violation

Single amino acid changes in the 6K1-CI region can promote the alternative adaptation of Prunus- and Nicotiana-propagated Plum pox virus C isolates to either host.

Science.gov (United States)

Calvo, María; Malinowski, Tadeusz; García, Juan Antonio

2014-02-01

Plum pox virus (PPV) C is one of the less common PPV strains and specifically infects cherry trees in nature. Making use of two PPV-C isolates that display different pathogenicity features, i.e., SwCMp, which had been adapted to Nicotiana species, and BY101, which had been isolated from cherry rootstock L2 (Prunus lannesiana) and propagated only in cherry species, we have generated two infective full-length cDNA clones in order to determine which viral factors are involved in the adaptation to each host. According to our results, the C-P3(PIPO)/6K1/N-CI (cylindrical inclusion) region contains overlapping but not coincident viral determinants involved in symptoms development, local viral amplification, and systemic movement capacity. Amino acid changes in this region promoting the adaptation to N. benthamiana or P. avium have trade-off effects in the alternative host. In both cases, adaptation can be achieved through single amino acid changes in the NIapro protease recognition motif between 6K1 and CI or in nearby sequences. Thus, we hypothesize that the potyvirus polyprotein processing could depend on specific host factors and the adaptation of PPV-C isolates to particular hosts relies on a fine regulation of the proteolytic cleavage of the 6K1-CI junction.

Molecular design for recombinant adeno-associated virus (rAAV) vector production.

Science.gov (United States)

Aponte-Ubillus, Juan Jose; Barajas, Daniel; Peltier, Joseph; Bardliving, Cameron; Shamlou, Parviz; Gold, Daniel

2018-02-01

Recombinant adeno-associated virus (rAAV) vectors are increasingly popular tools for gene therapy applications. Their non-pathogenic status, low inflammatory potential, availability of viral serotypes with different tissue tropisms, and prospective long-lasting gene expression are important attributes that make rAAVs safe and efficient therapeutic options. Over the last three decades, several groups have engineered recombinant AAV-producing platforms, yielding high titers of transducing vector particles. Current specific productivity yields from different platforms range from 10 3 to 10 5 vector genomes (vg) per cell, and there is an ongoing effort to improve vector yields in order to satisfy high product demands required for clinical trials and future commercialization.Crucial aspects of vector production include the molecular design of the rAAV-producing host cell line along with the design of AAV genes, promoters, and regulatory elements. Appropriately, configuring and balancing the expression of these elements not only contributes toward high productivity, it also improves process robustness and product quality. In this mini-review, the rational design of rAAV-producing expression systems is discussed, with special attention to molecular strategies that contribute to high-yielding, biomanufacturing-amenable rAAV production processes. Details on molecular optimization from four rAAV expression systems are covered: adenovirus, herpesvirus, and baculovirus complementation systems, as well as a recently explored yeast expression system.

About vectors

CERN Document Server

Hoffmann, Banesh

1975-01-01

From his unusual beginning in ""Defining a vector"" to his final comments on ""What then is a vector?"" author Banesh Hoffmann has written a book that is provocative and unconventional. In his emphasis on the unresolved issue of defining a vector, Hoffmann mixes pure and applied mathematics without using calculus. The result is a treatment that can serve as a supplement and corrective to textbooks, as well as collateral reading in all courses that deal with vectors. Major topics include vectors and the parallelogram law; algebraic notation and basic ideas; vector algebra; scalars and scalar p

Graphene materials as 2D non-viral gene transfer vector platforms.

Science.gov (United States)

Vincent, M; de Lázaro, I; Kostarelos, K

2017-03-01

Advances in genomics and gene therapy could offer solutions to many diseases that remain incurable today, however, one of the critical reasons halting clinical progress is due to the difficulty in designing efficient and safe delivery vectors for the appropriate genetic cargo. Safety and large-scale production concerns counter-balance the high gene transfer efficiency achieved with viral vectors, while non-viral strategies have yet to become sufficiently efficient. The extraordinary physicochemical, optical and photothermal properties of graphene-based materials (GBMs) could offer two-dimensional components for the design of nucleic acid carrier systems. We discuss here such properties and their implications for the optimization of gene delivery. While the design of such vectors is still in its infancy, we provide here an exhaustive and up-to-date analysis of the studies that have explored GBMs as gene transfer vectors, focusing on the functionalization strategies followed to improve vector performance and on the biological effects attained.

Babesial vector tick defensin against Babesia sp. parasites.

Science.gov (United States)

Tsuji, Naotoshi; Battsetseg, Badgar; Boldbaatar, Damdinsuren; Miyoshi, Takeharu; Xuan, Xuenan; Oliver, James H; Fujisaki, Kozo

2007-07-01

Antimicrobial peptides are major components of host innate immunity, a well-conserved, evolutionarily ancient defensive mechanism. Infectious disease-bearing vector ticks are thought to possess specific defense molecules against the transmitted pathogens that have been acquired during their evolution. We found in the tick Haemaphysalis longicornis a novel parasiticidal peptide named longicin that may have evolved from a common ancestral peptide resembling spider and scorpion toxins. H. longicornis is the primary vector for Babesia sp. parasites in Japan. Longicin also displayed bactericidal and fungicidal properties that resemble those of defensin homologues from invertebrates and vertebrates. Longicin showed a remarkable ability to inhibit the proliferation of merozoites, an erythrocyte blood stage of equine Babesia equi, by killing the parasites. Longicin was localized at the surface of the Babesia sp. parasites, as demonstrated by confocal microscopic analysis. In an in vivo experiment, longicin induced significant reduction of parasitemia in animals infected with the zoonotic and murine B. microti. Moreover, RNA interference data demonstrated that endogenous longicin is able to directly kill the canine B. gibsoni, thus indicating that it may play a role in regulating the vectorial capacity in the vector tick H. longicornis. Theoretically, longicin may serve as a model for the development of chemotherapeutic compounds against tick-borne disease organisms.

Timing of host feeding drives rhythms in parasite replication

KAUST Repository

Prior, Kimberley F.

2018-02-26

arena for studying host-parasite-vector coevolution and has broad implications for applied bioscience.

Extracellular secretion of recombinant proteins

Science.gov (United States)

Linger, Jeffrey G.; Darzins, Aldis

2014-07-22

Nucleic acids encoding secretion signals, expression vectors containing the nucleic acids, and host cells containing the expression vectors are disclosed. Also disclosed are polypeptides that contain the secretion signals and methods of producing polypeptides, including methods of directing the extracellular secretion of the polypeptides. Exemplary embodiments include cellulase proteins fused to secretion signals, methods to produce and isolate these polypeptides, and methods to degrade lignocellulosic biomass.

From Dietary Fiber to Host Physiology

DEFF Research Database (Denmark)

Koh, Ara; De Vadder, Filipe; Kovatcheva-Datchary, Petia

2016-01-01

executors of diet-based microbial influence on the host. Here, we will review data supporting the diverse functional roles carried out by a major class of bacterial metabolites, the short-chain fatty acids (SCFAs). SCFAs can directly activate G-coupled-receptors, inhibit histone deacetylases, and serve...

Immunoregulatory Effects Triggered by Lactic Acid Bacteria Exopolysaccharides: New Insights into Molecular Interactions with Host Cells

Directory of Open Access Journals (Sweden)

Jonathan Laiño

2016-08-01

Full Text Available Researchers have demonstrated that lactic acid bacteria (LAB with immunomodulatory capabilities (immunobiotics exert their beneficial effects through several molecules, including cell wall, peptidoglycan, and exopolysaccharides (EPS, that are able to interact with specific host cell receptors. EPS from LAB show a wide heterogeneity in its composition, meaning that biological properties depend on the strain and. therefore, only a part of the mechanism of action has been elucidated for these molecules. In this review, we summarize the current knowledge of the health-promoting actions of EPS from LAB with special focus on their immunoregulatory actions. In addition, we describe our studies using porcine intestinal epithelial cells (PIE cells as a model to evaluate the molecular interactions of EPS from two immunobiotic LAB strains and the host cells. Our studies showed that EPS from immunobiotic LAB have anti-inflammatory capacities in PIE cells since they are able to reduce the production of inflammatory cytokines in cells challenged with the Toll-like receptor (TLR-4-agonist lipopolysaccharide. The effects of EPS were dependent on TLR2, TLR4, and negative regulators of TLR signaling. We also reported that the radioprotective 105 (RP105/MD1 complex, a member of the TLR family, is partially involved in the immunoregulatory effects of the EPS from LAB. Our work described, for the first time, that LAB and their EPS reduce inflammation in intestinal epithelial cells in a RP105/MD1-dependent manner. A continuing challenge for the future is to reveal more effector-receptor relationships in immunobiotic-host interactions that contribute to the beneficial effects of these bacteria on mucosal immune homeostasis. A detailed molecular understanding should lead to a more rational use of immunobiotics in general, and their EPS in particular, as efficient prevention and therapies for specific immune-related disorders in humans and animals.

Synthetic sex pheromone attracts the leishmaniasis vector Lutzomyia longipalpis (Diptera: Psychodidae) to traps in the field.

Science.gov (United States)

Bray, D P; Bandi, K K; Brazil, R P; Oliveira, A G; Hamilton, J G C

2009-05-01

Improving vector control remains a key goal in reducing the world's burden of infectious diseases. More cost-effective approaches to vector control are urgently needed, particularly because vaccines are unavailable and treatment is prohibitively expensive. The causative agent of American visceral leishmaniasis (AVL), Leishmania chagasi, Cunha and Chagas (Kinetoplastida: Trypanosomatidae), is transmitted between animal and human hosts by blood-feeding female sand flies attracted to mating aggregations formed on or above host animals by male-produced sex pheromones. Our results show the potential of using synthetic pheromones to control populations of Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae), the sand fly vector of one of the world's most important neglected diseases, AVL. We showed that a synthetic pheromone, (+/-)-9-methylgermacrene-B, produced from a low-cost plant intermediate, attracted females in the laboratory. By formulating dispensers that released this pheromone at a rate similar to that released by aggregating males, we were able to attract flies of both sexes to traps in the field. These dispensers worked equally well when deployed with mechanical light traps and inexpensive sticky traps. If deployed effectively, pheromone-based traps could be used to decrease AVL transmission rates through specific targeting and reduction of L. longipalpis populations. This is the first study to show attraction of a human disease-transmitting insect to a synthetic pheromone in the field, showing the general applicability of this novel approach for developing new tools for use in vector control.

Synthetic Sex Pheromone Attracts the Leishmaniasis Vector Lutzomyia longipalpis (Diptera: Psychodidae) to Traps in the Field

Science.gov (United States)

Bray, D. P.; Bandi, K. K.; Brazil, R. P.; Oliveira, A. G.; Hamilton, J.G.C.

2011-01-01

Improving vector control remains a key goal in reducing the world’s burden of infectious diseases. More cost-effective approaches to vector control are urgently needed, particularly as vaccines are unavailable and treatment is prohibitively expensive. The causative agent of AVL, Leishmania chagasi, Cunha and Chagas (Kinetoplastida: Trypanosomatidae) is transmitted between animal and human hosts by blood-feeding female sand flies, attracted to mating aggregations formed on or above host animals by male-produced sex pheromones. Our results demonstrate the potential of using synthetic pheromones to control populations of Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae), the sand fly vector of one of the world’s most important neglected diseases, American visceral leishmaniasis (AVL). We showed that a synthetic pheromone, (±)-9-methylgermacrene-B, produced from a low-cost plant intermediate, attracted females in the laboratory. Then by formulating dispensers that released this pheromone at a rate similar to that released by aggregating males, we were able to attract flies of both sexes to traps in the field. These dispensers worked equally well when deployed with mechanical light traps and inexpensive sticky traps. If deployed effectively, pheromone-based traps could be used to decrease AVL transmission rates through specific targeting and reduction of L. longipalpis populations. This is the first study to show attraction of a human disease-transmitting insect to a synthetic pheromone in the field, demonstrating the general applicability of this novel approach for developing new tools for use in vector control. PMID:19496409

Using the Gravity Model to Estimate the Spatial Spread of Vector-Borne Diseases

Directory of Open Access Journals (Sweden)

Jean-Marie Aerts

2012-11-01

Full Text Available The gravity models are commonly used spatial interaction models. They have been widely applied in a large set of domains dealing with interactions amongst spatial entities. The spread of vector-borne diseases is also related to the intensity of interaction between spatial entities, namely, the physical habitat of pathogens’ vectors and/or hosts, and urban areas, thus humans. This study implements the concept behind gravity models in the spatial spread of two vector-borne diseases, nephropathia epidemica and Lyme borreliosis, based on current knowledge on the transmission mechanism of these diseases. Two sources of information on vegetated systems were tested: the CORINE land cover map and MODIS NDVI. The size of vegetated areas near urban centers and a local indicator of occupation-related exposure were found significant predictors of disease risk. Both the land cover map and the space-borne dataset were suited yet not equivalent input sources to locate and measure vegetated areas of importance for disease spread. The overall results point at the compatibility of the gravity model concept and the spatial spread of vector-borne diseases.

Vectors

DEFF Research Database (Denmark)

Boeriis, Morten; van Leeuwen, Theo

2017-01-01

should be taken into account in discussing ‘reactions’, which Kress and van Leeuwen link only to eyeline vectors. Finally, the question can be raised as to whether actions are always realized by vectors. Drawing on a re-reading of Rudolf Arnheim’s account of vectors, these issues are outlined......This article revisits the concept of vectors, which, in Kress and van Leeuwen’s Reading Images (2006), plays a crucial role in distinguishing between ‘narrative’, action-oriented processes and ‘conceptual’, state-oriented processes. The use of this concept in image analysis has usually focused...

Host cells and methods for producing isoprenyl alkanoates

Energy Technology Data Exchange (ETDEWEB)

Lee, Taek Soon; Fortman, Jeffrey L.; Keasling, Jay D.

2015-12-01

The invention provides for a method of producing an isoprenyl alkanoate in a genetically modified host cell. In one embodiment, the method comprises culturing a genetically modified host cell which expresses an enzyme capable of catalyzing the esterification of an isoprenol and a straight-chain fatty acid, such as an alcohol acetyltransferase (AAT), wax ester synthase/diacylglycerol acyltransferase (WS/DGAT) or lipase, under a suitable condition so that the isoprenyl alkanoate is produced.

Vector regression introduced

Directory of Open Access Journals (Sweden)

Mok Tik

2014-06-01

Full Text Available This study formulates regression of vector data that will enable statistical analysis of various geodetic phenomena such as, polar motion, ocean currents, typhoon/hurricane tracking, crustal deformations, and precursory earthquake signals. The observed vector variable of an event (dependent vector variable is expressed as a function of a number of hypothesized phenomena realized also as vector variables (independent vector variables and/or scalar variables that are likely to impact the dependent vector variable. The proposed representation has the unique property of solving the coefficients of independent vector variables (explanatory variables also as vectors, hence it supersedes multivariate multiple regression models, in which the unknown coefficients are scalar quantities. For the solution, complex numbers are used to rep- resent vector information, and the method of least squares is deployed to estimate the vector model parameters after transforming the complex vector regression model into a real vector regression model through isomorphism. Various operational statistics for testing the predictive significance of the estimated vector parameter coefficients are also derived. A simple numerical example demonstrates the use of the proposed vector regression analysis in modeling typhoon paths.

On the efficient bio-incorporation of 5-hydroxy-tryptophan in recombinant proteins expressed in Escherichia coli with T7 RNA polymerase-based vectors.

Science.gov (United States)

Oliveira-Souza, Wellington P; Bronze, Fellipe; Broos, Jaap; Marcondes, Marcelo F M; Oliveira, Vitor

2017-10-21

Biosynthetic incorporation of non-canonic amino acids is an attractive strategy to introduce new properties in recombinant proteins. Trp analogs can be incorporated in recombinant proteins replacing regular Trp during protein translation into a Trp-auxotrophic cell host. This straightforward method however, is limited to few analogs recognized and accepted by the cellular protein production machinery. 5-hydroxy-tryptophan (5OH-Trp) can be bio-incorporated using E. coli as expression host however; we have experienced very low incorporation yields - amount of protein containing regular Trp/amount of protein containing the Trp analog - during expressions of 5OH-Trp labeled proteins. Furthermore, this low incorporation yield were verified especially when the widely-used vectors based on the T7 RNA polymerase were used. Testing different 5OH-Trp incorporation protocols we verified that in these T7-based systems, the production of the T7 RNA polymerase is driven by the same elements - lac promoter/IPTG - as the target protein. Consequently, the bio-incorporation of the 5OH-Trp residues also occurs in this crucial enzyme, but, the produced T7 RNA polymerase labeled with 5OH-Trp is inactive or much less active. In the present work, we describe an efficient method to overcome this mentioned problem and bio-incorporate 5OH-Trp in proteins expressed in E. coli., using vectors based on the T7 RNA polymerase-T7 promoter. The two-step induction protocol here described showed incorporation efficiencies of 5OH-Trp higher than 90%. Copyright © 2017 Elsevier Inc. All rights reserved.

Genomic insights into the Ixodes scapularis tick vector of Lyme disease

Science.gov (United States)

Gulia-Nuss, Monika; Nuss, Andrew B.; Meyer, Jason M.; Sonenshine, Daniel E.; Roe, R. Michael; Waterhouse, Robert M.; Sattelle, David B.; de la Fuente, José; Ribeiro, Jose M.; Megy, Karine; Thimmapuram, Jyothi; Miller, Jason R.; Walenz, Brian P.; Koren, Sergey; Hostetler, Jessica B.; Thiagarajan, Mathangi; Joardar, Vinita S.; Hannick, Linda I.; Bidwell, Shelby; Hammond, Martin P.; Young, Sarah; Zeng, Qiandong; Abrudan, Jenica L.; Almeida, Francisca C.; Ayllón, Nieves; Bhide, Ketaki; Bissinger, Brooke W.; Bonzon-Kulichenko, Elena; Buckingham, Steven D.; Caffrey, Daniel R.; Caimano, Melissa J.; Croset, Vincent; Driscoll, Timothy; Gilbert, Don; Gillespie, Joseph J.; Giraldo-Calderón, Gloria I.; Grabowski, Jeffrey M.; Jiang, David; Khalil, Sayed M. S.; Kim, Donghun; Kocan, Katherine M.; Koči, Juraj; Kuhn, Richard J.; Kurtti, Timothy J.; Lees, Kristin; Lang, Emma G.; Kennedy, Ryan C.; Kwon, Hyeogsun; Perera, Rushika; Qi, Yumin; Radolf, Justin D.; Sakamoto, Joyce M.; Sánchez-Gracia, Alejandro; Severo, Maiara S.; Silverman, Neal; Šimo, Ladislav; Tojo, Marta; Tornador, Cristian; Van Zee, Janice P.; Vázquez, Jesús; Vieira, Filipe G.; Villar, Margarita; Wespiser, Adam R.; Yang, Yunlong; Zhu, Jiwei; Arensburger, Peter; Pietrantonio, Patricia V.; Barker, Stephen C.; Shao, Renfu; Zdobnov, Evgeny M.; Hauser, Frank; Grimmelikhuijzen, Cornelis J. P.; Park, Yoonseong; Rozas, Julio; Benton, Richard; Pedra, Joao H. F.; Nelson, David R.; Unger, Maria F.; Tubio, Jose M. C.; Tu, Zhijian; Robertson, Hugh M.; Shumway, Martin; Sutton, Granger; Wortman, Jennifer R.; Lawson, Daniel; Wikel, Stephen K.; Nene, Vishvanath M.; Fraser, Claire M.; Collins, Frank H.; Birren, Bruce; Nelson, Karen E.; Caler, Elisabet; Hill, Catherine A.

2016-01-01

Ticks transmit more pathogens to humans and animals than any other arthropod. We describe the 2.1 Gbp nuclear genome of the tick, Ixodes scapularis (Say), which vectors pathogens that cause Lyme disease, human granulocytic anaplasmosis, babesiosis and other diseases. The large genome reflects accumulation of repetitive DNA, new lineages of retro-transposons, and gene architecture patterns resembling ancient metazoans rather than pancrustaceans. Annotation of scaffolds representing ∼57% of the genome, reveals 20,486 protein-coding genes and expansions of gene families associated with tick–host interactions. We report insights from genome analyses into parasitic processes unique to ticks, including host ‘questing', prolonged feeding, cuticle synthesis, blood meal concentration, novel methods of haemoglobin digestion, haem detoxification, vitellogenesis and prolonged off-host survival. We identify proteins associated with the agent of human granulocytic anaplasmosis, an emerging disease, and the encephalitis-causing Langat virus, and a population structure correlated to life-history traits and transmission of the Lyme disease agent. PMID:26856261

Host-seeking behaviors of mosquitoes experimentally infected with sympatric field isolates of the human malaria parasite Plasmodium falciparum: no evidence for host manipulation

Directory of Open Access Journals (Sweden)

Amélie eVantaux

2015-08-01

Full Text Available Previous studies have shown that Plasmodium parasites can manipulate mosquito feeding behaviours such as motivation and avidity to feed on vertebrate hosts, in ways that increase the probability of parasite transmission. These studies, however, have been mainly carried out on non-natural and/or laboratory based model systems and hence may not reflect what occurs in the field. We now need to move closer to the natural setting, if we are to fully capture the ecological and evolutionary consequences of these parasite-induced behavioral changes. As part of this effort, we conducted a series of experiments to investigate the long and short-range behavioural responses to human stimuli in the mosquito Anopheles coluzzii during different stages of infection with sympatric field isolates of the human malaria parasite Plasmodium falciparum in Burkina Faso. First, we used a dual-port olfactometer designed to take advantage of the whole body odor to gauge mosquito long-range host-seeking behaviors. Second, we used a locomotor activity monitor system to assess mosquito short-range behaviors. Compared to control uninfected mosquitoes, P. falciparum infection had no significant effect neither on long-range nor on short-range behaviors both at the immature and mature stages. This study, using a natural mosquito-malaria parasite association, indicates that manipulation of vector behavior may not be a general phenomenon. We speculate that the observed contrasting phenotypes with model systems might result from coevolution of the human parasite and its natural vector. Future experiments, using other sympatric malaria mosquito populations or species are required to test this hypothesis. In conclusion, our results highlight the importance of following up discoveries in laboratory model systems with studies on natural parasite–mosquito interactions to accurately predict the epidemiological, ecological and evolutionary consequences of parasite manipulation of vector

Models of Disease Vector Control: When Can Aggressive Initial Intervention Lower Long-Term Cost?

Science.gov (United States)

Oduro, Bismark; Grijalva, Mario J; Just, Winfried

2018-04-01

Insecticide spraying of housing units is an important control measure for vector-borne infections such as Chagas disease. As vectors may invade both from other infested houses and sylvatic areas and as the effectiveness of insecticide wears off over time, the dynamics of (re)infestations can be approximated by [Formula: see text]-type models with a reservoir, where housing units are treated as hosts, and insecticide spraying corresponds to removal of hosts. Here, we investigate three ODE-based models of this type. We describe a dual-rate effect where an initially very high spraying rate can push the system into a region of the state space with low endemic levels of infestation that can be maintained in the long run at relatively moderate cost, while in the absence of an aggressive initial intervention the same average cost would only allow a much less significant reduction in long-term infestation levels. We determine some sufficient and some necessary conditions under which this effect occurs and show that it is robust in models that incorporate some heterogeneity in the relevant properties of housing units.

Kochen-Specker vectors

International Nuclear Information System (INIS)

Pavicic, Mladen; Merlet, Jean-Pierre; McKay, Brendan; Megill, Norman D

2005-01-01

We give a constructive and exhaustive definition of Kochen-Specker (KS) vectors in a Hilbert space of any dimension as well as of all the remaining vectors of the space. KS vectors are elements of any set of orthonormal states, i.e., vectors in an n-dimensional Hilbert space, H n , n≥3, to which it is impossible to assign 1s and 0s in such a way that no two mutually orthogonal vectors from the set are both assigned 1 and that not all mutually orthogonal vectors are assigned 0. Our constructive definition of such KS vectors is based on algorithms that generate MMP diagrams corresponding to blocks of orthogonal vectors in R n , on algorithms that single out those diagrams on which algebraic (0)-(1) states cannot be defined, and on algorithms that solve nonlinear equations describing the orthogonalities of the vectors by means of statistically polynomially complex interval analysis and self-teaching programs. The algorithms are limited neither by the number of dimensions nor by the number of vectors. To demonstrate the power of the algorithms, all four-dimensional KS vector systems containing up to 24 vectors were generated and described, all three-dimensional vector systems containing up to 30 vectors were scanned, and several general properties of KS vectors were found

Towards a resource-based habitat approach for spatial modelling of vector-borne disease risks.

Science.gov (United States)

Hartemink, Nienke; Vanwambeke, Sophie O; Purse, Bethan V; Gilbert, Marius; Van Dyck, Hans

2015-11-01

Given the veterinary and public health impact of vector-borne diseases, there is a clear need to assess the suitability of landscapes for the emergence and spread of these diseases. Current approaches for predicting disease risks neglect key features of the landscape as components of the functional habitat of vectors or hosts, and hence of the pathogen. Empirical-statistical methods do not explicitly incorporate biological mechanisms, whereas current mechanistic models are rarely spatially explicit; both methods ignore the way animals use the landscape (i.e. movement ecology). We argue that applying a functional concept for habitat, i.e. the resource-based habitat concept (RBHC), can solve these issues. The RBHC offers a framework to identify systematically the different ecological resources that are necessary for the completion of the transmission cycle and to relate these resources to (combinations of) landscape features and other environmental factors. The potential of the RBHC as a framework for identifying suitable habitats for vector-borne pathogens is explored and illustrated with the case of bluetongue virus, a midge-transmitted virus affecting ruminants. The concept facilitates the study of functional habitats of the interacting species (vectors as well as hosts) and provides new insight into spatial and temporal variation in transmission opportunities and exposure that ultimately determine disease risks. It may help to identify knowledge gaps and control options arising from changes in the spatial configuration of key resources across the landscape. The RBHC framework may act as a bridge between existing mechanistic and statistical modelling approaches. © 2014 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.

Test of the sheep ked Melophagus ovinus (L) as a vector of Anaplasma ovis Lestoquard.

Science.gov (United States)

Zaugg, J L; Coan, M E

1986-05-01

The sheep ked Melophagus ovinus was evaluated as a possible vector of Anaplasma ovis. In 4 tests, 45 to 293 keds were transferred from sheep with acute anaplasmosis, low level parasitemia, or carrier state of anaplasmosis to individual splenectomized ewes. Keds were confined in stockinette cages attached to the dorsal midline of the recipient hosts for 10 days. Throughout the 90-day observation periods after the keds were transferred, no clinical, serologic, or hematologic evidence of anaplasmosis was detected in any of the ked-recipient ewes. Results indicate that sheep keds probably are not mechanical or biological vectors of the ovine anaplasmosis organism.

Host-derived viral transporter protein for nitrogen uptake in infected marine phytoplankton

Science.gov (United States)

Chambouvet, Aurélie; Milner, David S.; Attah, Victoria; Terrado, Ramón; Lovejoy, Connie; Moreau, Hervé; Derelle, Évelyne; Richards, Thomas A.

2017-01-01

Phytoplankton community structure is shaped by both bottom–up factors, such as nutrient availability, and top–down processes, such as predation. Here we show that marine viruses can blur these distinctions, being able to amend how host cells acquire nutrients from their environment while also predating and lysing their algal hosts. Viral genomes often encode genes derived from their host. These genes may allow the virus to manipulate host metabolism to improve viral fitness. We identify in the genome of a phytoplankton virus, which infects the small green alga Ostreococcus tauri, a host-derived ammonium transporter. This gene is transcribed during infection and when expressed in yeast mutants the viral protein is located to the plasma membrane and rescues growth when cultured with ammonium as the sole nitrogen source. We also show that viral infection alters the nature of nitrogen compound uptake of host cells, by both increasing substrate affinity and allowing the host to access diverse nitrogen sources. This is important because the availability of nitrogen often limits phytoplankton growth. Collectively, these data show that a virus can acquire genes encoding nutrient transporters from a host genome and that expression of the viral gene can alter the nutrient uptake behavior of host cells. These results have implications for understanding how viruses manipulate the physiology and ecology of phytoplankton, influence marine nutrient cycles, and act as vectors for horizontal gene transfer. PMID:28827361

Colorimetric tests for diagnosis of filarial infection and vector surveillance using non-instrumented nucleic acid loop-mediated isothermal amplification (NINA-LAMP.

Directory of Open Access Journals (Sweden)

Catherine B Poole

Full Text Available Accurate detection of filarial parasites in humans is essential for the implementation and evaluation of mass drug administration programs to control onchocerciasis and lymphatic filariasis. Determining the infection levels in vector populations is also important for assessing transmission, deciding when drug treatments may be terminated and for monitoring recrudescence. Immunological methods to detect infection in humans are available, however, cross-reactivity issues have been reported. Nucleic acid-based molecular assays offer high levels of specificity and sensitivity, and can be used to detect infection in both humans and vectors. In this study we developed loop-mediated isothermal amplification (LAMP tests to detect three different filarial DNAs in human and insect samples using pH sensitive dyes for enhanced visual detection of amplification. Furthermore, reactions were performed in a portable, non-instrumented nucleic acid amplification (NINA device that provides a stable heat source for LAMP. The efficacy of several strand displacing DNA polymerases were evaluated in combination with neutral red or phenol red dyes. Colorimetric NINA-LAMP assays targeting Brugia Hha I repeat, Onchocerca volvulus GST1a and Wuchereria bancrofti LDR each exhibit species-specificity and are also highly sensitive, detecting DNA equivalent to 1/10-1/5000th of one microfilaria. Reaction times varied depending on whether a single copy gene (70 minutes, O. volvulus or repetitive DNA (40 min, B. malayi and W. bancrofti was employed as a biomarker. The NINA heater can be used to detect multiple infections simultaneously. The accuracy, simplicity and versatility of the technology suggests that colorimetric NINA-LAMP assays are ideally suited for monitoring the success of filariasis control programs.

Transfer of phloem-mobile substances from the host plants to the holoparasite Cuscuta sp.

Science.gov (United States)

Birschwilks, Mandy; Haupt, Sophie; Hofius, Daniel; Neumann, Stefanie

2006-01-01

During the development of the haustorium, searching hyphae of the parasite and the host parenchyma cells are connected by plasmodesmata. Using transgenic tobacco plants expressing a GFP-labelled movement protein of the tobacco mosaic virus, it was demonstrated that the interspecific plasmodesmata are open. The transfer of substances in the phloem from host to the parasite is not selective. After simultaneous application of (3)H-sucrose and (14)C-labelled phloem-mobile amino acids, phytohormones, and xenobiotica to the host, corresponding percentages of the translocated compounds are found in the parasite. An open continuity between the host phloem and the Cuscuta phloem via the haustorium was demonstrated in CLSM pictures after application of the phloem-mobile fluorescent probes, carboxyfluorescein (CF) and hydroxypyrene trisulphonic acid (HPTS), to the host. Using a Cuscuta bridge (14)C-sucrose and the virus PVY(N) were transferred from one host plant to the another. The results of translocation experiments with labelled compounds, phloem-mobile dyes and the virus should be considered as unequivocal evidence for a symplastic transfer of phloem solutes between Cuscuta species and their compatible hosts.

Elementary vectors

CERN Document Server

Wolstenholme, E Œ

1978-01-01

Elementary Vectors, Third Edition serves as an introductory course in vector analysis and is intended to present the theoretical and application aspects of vectors. The book covers topics that rigorously explain and provide definitions, principles, equations, and methods in vector analysis. Applications of vector methods to simple kinematical and dynamical problems; central forces and orbits; and solutions to geometrical problems are discussed as well. This edition of the text also provides an appendix, intended for students, which the author hopes to bridge the gap between theory and appl

Vector-virus mutualism accelerates population increase of an invasive whitefly.

Directory of Open Access Journals (Sweden)

Min Jiu

2007-01-01

Full Text Available The relationships between plant viruses, their herbivore vectors and host plants can be beneficial, neutral, or antagonistic, depending on the species involved. This variation in relationships may affect the process of biological invasion and the displacement of indigenous species by invaders when the invasive and indigenous organisms occur with niche overlap but differ in the interactions. The notorious invasive B biotype of the whitefly complex Bemisia tabaci entered China in the late 1990s and is now the predominant or only biotype in many regions of the country. Tobacco curly shoot virus (TbCSV and Tomato yellow leaf curl China virus (TYLCCNV are two whitefly-transmitted begomoviruses that have become widespread recently in south China. We compared the performance of the invasive B and indigenous ZHJ1 whitefly biotypes on healthy, TbCSV-infected and TYLCCNV-infected tobacco plants. Compared to its performance on healthy plants, the invasive B biotype increased its fecundity and longevity by 12 and 6 fold when feeding on TbCSV-infected plants, and by 18 and 7 fold when feeding on TYLCCNV-infected plants. Population density of the B biotype on TbCSV- and TYLCCNV-infected plants reached 2 and 13 times that on healthy plants respectively in 56 days. In contrast, the indigenous ZHJ1 performed similarly on healthy and virus-infected plants. Virus-infection status of the whiteflies per se of both biotypes showed limited effects on performance of vectors on cotton, a nonhost plant of the viruses. The indirect mutualism between the B biotype whitefly and these viruses via their host plants, and the apparent lack of such mutualism for the indigenous whitefly, may contribute to the ability of the B whitefly biotype to invade, the displacement of indigenous whiteflies, and the disease pandemics of the viruses associated with this vector.

Canine vector-borne co-infections: Ehrlichia canis and Hepatozoon canis in the same host monocytes.

Science.gov (United States)

Baneth, Gad; Harrus, Shimon; Gal, Arnon; Aroch, Itamar

2015-02-28

The protozoon Hepatozoon canis and the rickettsia Ehrlichia canis are tick-borne pathogens, transmitted by Rhipicephalus sanguineus, which cause canine hepatozoonosis and canine monocytic ehrlichiosis, respectively. Co-infection of the same host monocytes with H. canis and E. canis confirmed by molecular characterization of the infecting agents and quantitative assessment of co-infected cells is described for the first time in three naturally-infected dogs. Blood smear evaluation indicated that at least 50% of the leukocytes infected with H. canis gamonts contained E. canis morulae. Co-infection of the same host cell demonstrated in this report suggests that infection with one pathogen may permit or enhance invasion or prolonged cellular survival of the other. Copyright © 2014 Elsevier B.V. All rights reserved.

A three-genome phylogeny of malaria parasites (Plasmodium and closely related genera): evolution of life-history traits and host switches.

Science.gov (United States)

Martinsen, Ellen S; Perkins, Susan L; Schall, Jos J

2008-04-01

Phylogenetic analysis of genomic data allows insights into the evolutionary history of pathogens, especially the events leading to host switching and diversification, as well as alterations of the life cycle (life-history traits). Hundreds, perhaps thousands, of malaria parasite species exploit squamate reptiles, birds, and mammals as vertebrate hosts as well as many genera of dipteran vectors, but the evolutionary and ecological events that led to this diversification and success remain unresolved. For a century, systematic parasitologists classified malaria parasites into genera based on morphology, life cycle, and vertebrate and insect host taxa. Molecular systematic studies based on single genes challenged the phylogenetic significance of these characters, but several significant nodes were not well supported. We recovered the first well resolved large phylogeny of Plasmodium and related haemosporidian parasites using sequence data for four genes from the parasites' three genomes by combining all data, correcting for variable rates of substitution by gene and site, and using both Bayesian and maximum parsimony analyses. Major clades are associated with vector shifts into different dipteran families, with other characters used in traditional parasitological studies, such as morphology and life-history traits, having variable phylogenetic significance. The common parasites of birds now placed into the genus Haemoproteus are found in two divergent clades, and the genus Plasmodium is paraphyletic with respect to Hepatocystis, a group of species with very different life history and morphology. The Plasmodium of mammal hosts form a well supported clade (including Plasmodium falciparum, the most important human malaria parasite), and this clade is associated with specialization to Anopheles mosquito vectors. The Plasmodium of birds and squamate reptiles all fall within a single clade, with evidence for repeated switching between birds and squamate hosts.

Ixodes ricinus ticks are reservoir hosts for Rickettsia helvetica and potentially carry flea-borne Rickettsia species.

NARCIS (Netherlands)

Sprong, H.; Wielinga, P.R.; Fonville, M.; Reusken, C.; Brandenburg, A.H.; Borgsteede, F.H.M.

2009-01-01

Background - Hard ticks have been identified as important vectors of rickettsiae causing the spotted fever syndrome. Tick-borne rickettsiae are considered to be emerging, but only limited data are available about their presence in Western Europe, their natural life cycle and their reservoir hosts.

Alteration of intersubunit acid–base pair interactions at the quasi-threefold axis of symmetry of Cucumber mosaic virus disrupts aphid vector transmission

International Nuclear Information System (INIS)

Bricault, Christine A.; Perry, Keith L.

2013-01-01

In the atomic model of Cucumber mosaic virus (CMV), six amino acid residues form stabilizing salt bridges between subunits of the asymmetric unit at the quasi-threefold axis of symmetry. To evaluate the effects of these positions on virion stability and aphid vector transmissibility, six charged amino acid residues were individually mutated to alanine. All of the six engineered viruses were viable and exhibited near wild type levels of virion stability in the presence of urea. Aphid vector transmissibility was nearly or completely eliminated in the case of four of the mutants; two mutants demonstrated intermediate aphid transmissibility. For the majority of the engineered mutants, second-site mutations were observed following aphid transmission and/or mechanical passaging, and one restored transmission rates to that of the wild type. CMV capsids tolerate disruption of acid–base pairing interactions at the quasi-threefold axis of symmetry, but these interactions are essential for maintaining aphid vector transmissibility. - Highlights: ► Amino acids between structural subunits of Cucumber mosaic virus affect vector transmission. ► Mutant structural stability was retained, while aphid vector transmissibility was disrupted. ► Spontaneous, second-site mutations restored aphid vector transmissibility

Alteration of intersubunit acid–base pair interactions at the quasi-threefold axis of symmetry of Cucumber mosaic virus disrupts aphid vector transmission

Energy Technology Data Exchange (ETDEWEB)

Bricault, Christine A. [Department of Plant Pathology and Plant-Microbe Biology, 334 Plant Science Building, Cornell University, Ithaca, NY 14850 (United States); Perry, Keith L., E-mail: KLP3@cornell.edu [Department of Plant Pathology and Plant-Microbe Biology, 334 Plant Science Building, Cornell University, Ithaca, NY 14850 (United States)

2013-06-05

In the atomic model of Cucumber mosaic virus (CMV), six amino acid residues form stabilizing salt bridges between subunits of the asymmetric unit at the quasi-threefold axis of symmetry. To evaluate the effects of these positions on virion stability and aphid vector transmissibility, six charged amino acid residues were individually mutated to alanine. All of the six engineered viruses were viable and exhibited near wild type levels of virion stability in the presence of urea. Aphid vector transmissibility was nearly or completely eliminated in the case of four of the mutants; two mutants demonstrated intermediate aphid transmissibility. For the majority of the engineered mutants, second-site mutations were observed following aphid transmission and/or mechanical passaging, and one restored transmission rates to that of the wild type. CMV capsids tolerate disruption of acid–base pairing interactions at the quasi-threefold axis of symmetry, but these interactions are essential for maintaining aphid vector transmissibility. - Highlights: ► Amino acids between structural subunits of Cucumber mosaic virus affect vector transmission. ► Mutant structural stability was retained, while aphid vector transmissibility was disrupted. ► Spontaneous, second-site mutations restored aphid vector transmissibility.

Vertebrate hosts and phylogenetic relationships of amphibian trypanosomes from a potential invertebrate vector, Culex territans Walker (Diptera: Culicidae).

Science.gov (United States)

Bartlett-Healy, Kristen; Crans, Wayne; Gaugler, Randy

2009-04-01

The blood meals of field-collected female Culex territans (Diptera: Culicidae) were concurrently assayed for the presence of trypanosomes and for vertebrate host identification. We amplified vertebrate DNA in 42 of 119 females and made positive identification to the host species level in 29 of those samples. Of the 119 field-collected Cx. territans females, 24 were infected with trypanosomes. Phylogenetic analysis placed the trypanosomes in the amphibian portion of the aquatic clade of the Trypanosomatidae. These trypanosomes were isolated from Cx. territans females that had fed on the frog species Rana clamitans, R. catesbeiana, R. virgatipes, and Rana spp. Results support a potential new lineage of dipteran-transmitted amphibian trypanosomes may occur within the aquatic clade. The frequency in which female Cx. territans acquire trypanosomes, through diverse feeding habits, indicates a new relationship between amphibian trypanosomes and mosquitoes that has not been examined previously. Combining Trypanosoma species, invertebrate, and vertebrate hosts to existing phylogenies can elucidate trypanosome and host relationships.

Emergence of epizootic ulcerative syndrome in native fish of the Murray-Darling River System, Australia: hosts, distribution and possible vectors.

Directory of Open Access Journals (Sweden)

Craig A Boys

Full Text Available Epizootic ulcerative syndrome (EUS is a fish disease of international significance and reportable to the Office International des Epizootics. In June 2010, bony herring Nematalosa erebi, golden perch Macquaria ambigua, Murray cod Maccullochella peelii and spangled perch Leiopotherapon unicolor with severe ulcers were sampled from the Murray-Darling River System (MDRS between Bourke and Brewarrina, New South Wales Australia. Histopathology and polymerase chain reaction identified the fungus-like oomycete Aphanomyces invadans, the causative agent of EUS. Apart from one previous record in N. erebi, EUS has been recorded in the wild only from coastal drainages in Australia. This study is the first published account of A. invadans in the wild fish populations of the MDRS, and is the first confirmed record of EUS in M. ambigua, M. peelii and L. unicolor. Ulcerated carp Cyprinus carpio collected at the time of the same epizootic were not found to be infected by EUS, supporting previous accounts of resistance against the disease by this species. The lack of previous clinical evidence, the large number of new hosts (n = 3, the geographic extent (200 km of this epizootic, the severity of ulceration and apparent high pathogenicity suggest a relatively recent invasion by A. invadans. The epizootic and associated environmental factors are documented and discussed within the context of possible vectors for its entry into the MDRS and recommendations regarding continued surveillance, research and biosecurity are made.

Genome sequence of the tsetse fly (Glossina morsitans ): Vector of African trypanosomiasis

KAUST Repository

Watanabe, Junichi

2014-04-24

Tsetse flies are the sole vectors of human African trypanosomiasis throughout sub-Saharan Africa. Both sexes of adult tsetse feed exclusively on blood and contribute to disease transmission. Notable differences between tsetse and other disease vectors include obligate microbial symbioses, viviparous reproduction, and lactation. Here, we describe the sequence and annotation of the 366-megabase Glossina morsitans morsitans genome. Analysis of the genome and the 12,308 predicted protein-encoding genes led to multiple discoveries, including chromosomal integrations of bacterial (Wolbachia) genome sequences, a family of lactation-specific proteins, reduced complement of host pathogen recognition proteins, and reduced olfaction/chemosensory associated genes. These genome data provide a foundation for research into trypanosomiasis prevention and yield important insights with broad implications for multiple aspects of tsetse biology.

Genome sequence of the tsetse fly (Glossina morsitans ): Vector of African trypanosomiasis

KAUST Repository

Watanabe, Junichi; Hattori, Masahira; Berriman, Matthew; Lehane, Michael J.; Hall, Neil; Solano, Philippe; Aksoy, Serap; Hide, Winston; Touré , Yé ya Tié moko; Attardo, Geoffrey M.; Darby, Alistair Charles; Toyoda, Atsushi; Hertz-Fowler, Christiane; Larkin, Denis M.; Cotton, James A.; Sanders, Mandy J.; Swain, Martin T.; Quail, Michael A.; Inoue, Noboru; Ravel, Sophie; Taylor, Todd Duane; Srivastava, Tulika P.; Sharma, Vineet Kumar; Warren, Wesley C.; Wilson, Richard K.; Suzuki, Yutaka; Lawson, Daniel; Hughes, Daniel Seth Toney; Megy, Karyn; Masiga, Daniel K.; Mireji, Paul Odhiambo; Hansen, Immo Alex; Van Den Abbeele, Jan; Benoit, Joshua B.; Bourtzis, Kostas; Obiero, George F O; Robertson, Hugh M.; Jones, Jeffery W.; Zhou, Jingjiang; Field, Linda M.; Friedrich, Markus; Nyanjom, Steven R G; Telleria, Erich Loza; Caljon, Guy; Ribeiro, José M. C.; Acosta-Serrano, Alvaro; Ooi, Cherpheng; Rose, Clair; Price, David P.; Haines, Lee Rafuse; Christoffels, Alan G.; Sim, Cheolho; Pham, Daphne Q D; Denlinger, David L.; Geiser, Dawn L.; Omedo, Irene A.; Winzerling, Joy J.; Peyton, Justin T.; Marucha, Kevin K.; Jonas, Mario; Meuti, Megan E.; Rawlings, Neil David; Zhang, Qirui; Macharia, Rosaline Wanjiru; Michalkova, Veronika; Dashti, Zahra Jalali Sefid; Baumann, Aaron A.; Gä de, Gerd; Marco, Heather G.; Caers, Jelle; Schoofs, Liliane; Riehle, Michael A.; Hu, Wanqi; Tu, Zhijian; Tarone, Aaron M.; Malacrida, Anna Rodolfa; Kibet, Caleb K.; Scolari, Francesca; Koekemoer, J. J. O.; Willis, Judith H.; Gomulski, Ludvik M.; Falchetto, Marco; Scott, Maxwell J.; Fu, Shuhua; Sze, Singhoi; Luiz, Thiago; Weiss, Brian L.; Walshe, Deirdre P.; Wang, Jingwen; Wamalwa, Mark; Mwangi, Sarah; Ramphul, Urvashi N.; Snyder, Anna K.; Brelsfoard, Corey L.; Thomas, Gavin H.; Tsiamis, George; Arensburger, Peter; Rio, Rita V M; Macdonald, Sandy J.; Panji, Sumir; Kruger, Adele F.; Benkahla, Alia; Balyeidhusa, Apollo Simon Peter; Msangi, Atway R.; Okoro, Chinyere K.; Stephens, Dawn; Stanley, Eleanor J.; Mpondo, Feziwe; Wamwiri, Florence N.; Mramba, Furaha; Siwo, Geoffrey H.; Githinji, George; Harkins, Gordon William; Murilla, Grace Adira; Lehvä slaiho, Heikki; Malele, Imna I.; Auma, Joanna Eseri; Kinyua, Johnson K.; Ouma, Johnson O.; Okedi, Loyce M A; Manga, Lucien; Aslett, Martin A.; Koffi, Mathurin; Gaunt, Michael W.; Makgamathe, Mmule; Mulder, Nicola Jane; Manangwa, Oliver; Abila, Patrick P.; Wincker, Patrick; Gregory, Richard I.; Bateta, Rosemary; Sakate, Ryuichi; Ommeh, Sheila; Lehane, Stella M.; Imanishi, Tadashi; Osamor, Victor Chukwudi; Kawahara, Yoshihiro

2014-01-01

Tsetse flies are the sole vectors of human African trypanosomiasis throughout sub-Saharan Africa. Both sexes of adult tsetse feed exclusively on blood and contribute to disease transmission. Notable differences between tsetse and other disease vectors include obligate microbial symbioses, viviparous reproduction, and lactation. Here, we describe the sequence and annotation of the 366-megabase Glossina morsitans morsitans genome. Analysis of the genome and the 12,308 predicted protein-encoding genes led to multiple discoveries, including chromosomal integrations of bacterial (Wolbachia) genome sequences, a family of lactation-specific proteins, reduced complement of host pathogen recognition proteins, and reduced olfaction/chemosensory associated genes. These genome data provide a foundation for research into trypanosomiasis prevention and yield important insights with broad implications for multiple aspects of tsetse biology.

Weak Organic Acids Decrease Borrelia burgdorferi Cytoplasmic pH, Eliciting an Acid Stress Response and Impacting RpoN- and RpoS-Dependent Gene Expression

Directory of Open Access Journals (Sweden)

Daniel P. Dulebohn

2017-09-01

Full Text Available The spirochete Borrelia burgdorferi survives in its tick vector, Ixodes scapularis, or within various hosts. To transition between and survive in these distinct niches, B. burgdorferi changes its gene expression in response to environmental cues, both biochemical and physiological. Exposure of B. burgdorferi to weak monocarboxylic organic acids, including those detected in the blood meal of fed ticks, decreased the cytoplasmic pH of B. burgdorferi in vitro. A decrease in the cytoplasmic pH induced the expression of genes encoding enzymes that have been shown to restore pH homeostasis in other bacteria. These include putative coupled proton/cation exchangers, a putative Na+/H+ antiporter, a neutralizing buffer transporter, an amino acid deaminase and a proton exporting vacuolar-type VoV1 ATPase. Data presented in this report suggested that the acid stress response triggered the expression of RpoN- and RpoS-dependent genes including important virulence factors such as outer surface protein C (OspC, BBA66, and some BosR (Borreliaoxidative stress regulator-dependent genes. Because the expression of virulence factors, like OspC, are so tightly connected by RpoS to general cellular stress responses and cell physiology, it is difficult to separate transmission-promoting conditions in what is clearly a multifactorial and complex regulatory web.

Microsphere-liposome complexes protect adenoviral vectors from neutralising antibody without losses in transfection efficiency, in-vitro.

Science.gov (United States)

Steel, Jason C; Cavanagh, Heather M A; Burton, Mark A; Kalle, Wouter H J

2004-11-01

Adenoviral vectors have been commonly used in gene therapy protocols but the success of their use is often limited by the induction of host immunity to the vector. Following exposure to the adenoviral vector, adenoviral-specific neutralising antibodies are produced, which limits further administration. This study examines the effectiveness of a novel combination of microspheres and liposomes for the shielding of adenovirus from neutralising antibodies in an in-vitro setting. We show that liposomes are effective in the protection of adenovirus from neutralising antibody and that the conjugation of these complexes to microspheres augments the level of protection. This study further reveals that previously neutralised adenovirus may still be transported into the cell via liposome-cell interactions and is still capable of expressing its genes, making this vector an effective tool for circumvention of the humoral immune response. We also looked at possible side effects of using the complexes, namely increases in cytotoxicity and reductions in transfection efficiency. Our results showed that varying the liposome:adenovirus ratio can reduce the cytotoxicity of the vector as well as increase the transfection efficiency. In addition, in cell lines that are adenoviral competent, transfection efficiencies on par with uncomplexed adenoviral vectors were achievable with the combination vector.

Cloning and Expression Vector Construction of Glutamate Decarboxylase Gene from Lactobacillus Plantarum

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B Arabpour

2016-06-01

Full Text Available BACKGROUND AND OBJECTIVE: Gamma-aminobutyric acid (GABA is a four-carbon non-protein amino acid used in the treatment of hypertension, diabetes, inflammation, and depression. GABA is synthesized by glutamic acid decarboxylase (GAD enzyme in many organisms, including bacteria. Therefore, cloning of this enzyme is essential to the optimization of GABA production. This study aimed to clone and construct the expression vector of GAD gene from Lactobacillus plantarum PTCC 1058 bacterium. METHODS: In this experimental study, we investigated the morphological, biochemical, genetic and 16s rDNA sequencing of L. plantarum PTCC 1058 strain. Genomic DNA of the bacterium was isolated and amplified using the GAD gene via polymerase chain reaction (PCR. Afterwards, the gene was inserted into the pJET1.2/blunt cloning vector and subcloned in vector pET32a. Plasmid pET32a-gad expression vector was transformed in Escherichia coli BL21 strain, and protein expression was assessed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE. FINDINGS: Morphological, biochemical and genetic analyses of 16s rDNA sequencing indicated that the studied substrain was of the L. plantarum strain. In addition, results of nucleotide sequencing of the fragmented segment via PCR showed the presence of GAD gene. Results of colony PCR and SDS-PAGE analysis confirmed the accuracy of the cloning and gene expression of the recombinant Escherichia coli BL21 strain. CONCLUSION: According to the results of this study, cloning of GAD gene from L. plantarum PTCC 1058 was successful. These cloned genes could grow rapidly in prokaryotic and eukaryotic systems and be used in cost-effective culture media and even non-recyclable waste.

Tracer techniques for the study of host-parasite relations

International Nuclear Information System (INIS)

Mendgen, K.

1975-01-01

Autoradiographic techniques have been used to study the interaction of many facultative and obligate parasites, including viruses. After feeding the host plant with labelled substrates, labelled material accumulates in the infected cells and seems to penetrate into structures of the parasite. After labelling the parasite, its influence on the host may be studied. We use this technique to study the interaction of host (bean) and parasite (bean rust) during the infection process. After infection with uredospores labelled with tritiated orotic acid, the radioactivity is retained almost completely within the young haustorium at 22 h after inoculation. This may indicate a very small influence of the parasite on its compatible host. In incompatible host-parasite combinations, the infection process proceeds in a different way. The use of autoradiographic techniques to compare combinations of varying compatibilities will be discussed. (author)

[Overexpression of four fatty acid synthase genes elevated the efficiency of long-chain polyunsaturated fatty acids biosynthesis in mammalian cells].

Science.gov (United States)

Zhu, Guiming; Saleh, Abdulmomen Ali Mohammed; Bahwal, Said Ahmed; Wang, Kunfu; Wang, Mingfu; Wang, Didi; Ge, Tangdong; Sun, Jie

2014-09-01

Three long-chain polyunsaturated fatty acids, docosahexaenoic acid (DHA, 22:6n-3), eicosapentaenoic acid (EPA, 20:5n-3) and arachidonic acid (ARA, 20:4n-6), are the most biologically active polyunsaturated fatty acids in the body. They are important in developing and maintaining the brain function, and in preventing and treating many diseases such as cardiovascular disease, inflammation and cancer. Although mammals can biosynthesize these long-chain polyunsaturated fatty acids, the efficiency is very low and dietary intake is needed to meet the requirement. In this study, a multiple-genes expression vector carrying mammalian A6/A5 fatty acid desaturases and multiple-genes expression vector carrying mammalian Δ6/Δ5 fatty acid desaturases and Δ6/Δ5 fatty acid elongases coding genes was used to transfect HEK293T cells, then the overexpression of the target genes was detected. GC-MS analysis shows that the biosynthesis efficiency and level of DHA, EPA and ARA were significantly increased in cells transfected with the multiple-genes expression vector. Particularly, DHA level in these cells was 2.5 times higher than in the control cells. This study indicates mammal possess a certain mechanism for suppression of high level of biosynthesis of long chain polyunsaturated fatty acids, and the overexpression of Δ6/Δ5 fatty acid desaturases and Δ6/Δ5 fatty acid elongases broke this suppression mechanism so that the level of DHA, EPA and ARA was significantly increased. This study also provides a basis for potential applications of this gene construct in transgenic animal to produce high level of these long-chain polyunsaturated fatty acid.

Ixodes ricinus ticks are reservoir hosts for Rickettsia helvetica and potentially carry flea-borne Rickettsia species

Directory of Open Access Journals (Sweden)

Gaasenbeek Cor

2009-09-01

Full Text Available Abstract Background Hard ticks have been identified as important vectors of rickettsiae causing the spotted fever syndrome. Tick-borne rickettsiae are considered to be emerging, but only limited data are available about their presence in Western Europe, their natural life cycle and their reservoir hosts. Ixodes ricinus, the most prevalent tick species, were collected and tested from different vegetation types and from potential reservoir hosts. In one biotope area, the annual and seasonal variability of rickettsiae infections of the different tick stages were determined for 9 years. Results The DNA of the human pathogen R. conorii as well as R. helvetica, R. sp. IRS and R. bellii-like were found. Unexpectedly, the DNA of the highly pathogenic R. typhi and R. prowazekii and 4 other uncharacterized Rickettsia spp. related to the typhus group were also detected in I. ricinus. The presence of R. helvetica in fleas isolated from small rodents supported our hypothesis that cross-infection can occur under natural conditions, since R. typhi/prowazekii and R. helvetica as well as their vectors share rodents as reservoir hosts. In one biotope, the infection rate with R. helvetica was ~66% for 9 years, and was comparable between larvae, nymphs, and adults. Larvae caught by flagging generally have not yet taken a blood meal from a vertebrate host. The simplest explanation for the comparable prevalence of R. helvetica between the defined tick stages is, that R. helvetica is vertically transmitted through the next generation with high efficiency. The DNA of R. helvetica was also present in whole blood from mice, deer and wild boar. Conclusion Besides R. helvetica, unexpected rickettsiae are found in I. ricinus ticks. We propose that I. ricinus is a major reservoir host for R. helvetica, and that vertebrate hosts play important roles in the further geographical dispersion of rickettsiae.

Systems and methods for the secretion of recombinant proteins in gram negative bacteria

Science.gov (United States)

Withers, III, Sydnor T.; Dominguez, Miguel A; DeLisa, Matthew P.; Haitjema, Charles H.

2016-08-09

Disclosed herein are systems and methods for producing recombinant proteins utilizing mutant E. coli strains containing expression vectors carrying nucleic acids encoding the proteins, and secretory signal sequences to direct the secretion of the proteins to the culture medium. Host cells transformed with the expression vectors are also provided.

Systems and methods for the secretion of recombinant proteins in gram negative bacteria

Energy Technology Data Exchange (ETDEWEB)

Withers, III, Sydnor T.; Dominguez, Miguel A.; DeLisa, Matthew P.; Haitjema, Charles H.

2017-02-21

Disclosed herein are systems and methods for producing recombinant proteins utilizing mutant E. coli strains containing expression vectors carrying nucleic acids encoding the proteins, and secretory signal sequences to direct the secretion of the proteins to the culture medium. Host cells transformed with the expression vectors are also provided.

Trichoderma .beta.-glucosidase

Science.gov (United States)

Dunn-Coleman, Nigel; Goedegebuur, Frits; Ward, Michael; Yao, Jian

2006-01-03

The present invention provides a novel .beta.-glucosidase nucleic acid sequence, designated bgl3, and the corresponding BGL3 amino acid sequence. The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding BGL3, recombinant BGL3 proteins and methods for producing the same.

Noroviruses Co-opt the Function of Host Proteins VAPA and VAPB for Replication via a Phenylalanine-Phenylalanine-Acidic-Tract-Motif Mimic in Nonstructural Viral Protein NS1/2.

Science.gov (United States)

McCune, Broc T; Tang, Wei; Lu, Jia; Eaglesham, James B; Thorne, Lucy; Mayer, Anne E; Condiff, Emily; Nice, Timothy J; Goodfellow, Ian; Krezel, Andrzej M; Virgin, Herbert W

2017-07-11

The Norovirus genus contains important human pathogens, but the role of host pathways in norovirus replication is largely unknown. Murine noroviruses provide the opportunity to study norovirus replication in cell culture and in small animals. The human norovirus nonstructural protein NS1/2 interacts with the host protein VAMP-associated protein A (VAPA), but the significance of the NS1/2-VAPA interaction is unexplored. Here we report decreased murine norovirus replication in VAPA- and VAPB-deficient cells. We characterized the role of VAPA in detail. VAPA was required for the efficiency of a step(s) in the viral replication cycle after entry of viral RNA into the cytoplasm but before the synthesis of viral minus-sense RNA. The interaction of VAPA with viral NS1/2 proteins is conserved between murine and human noroviruses. Murine norovirus NS1/2 directly bound the major sperm protein (MSP) domain of VAPA through its NS1 domain. Mutations within NS1 that disrupted interaction with VAPA inhibited viral replication. Structural analysis revealed that the viral NS1 domain contains a mimic of the phenylalanine-phenylalanine-acidic-tract (FFAT) motif that enables host proteins to bind to the VAPA MSP domain. The NS1/2-FFAT mimic region interacted with the VAPA-MSP domain in a manner similar to that seen with bona fide host FFAT motifs. Amino acids in the FFAT mimic region of the NS1 domain that are important for viral replication are highly conserved across murine norovirus strains. Thus, VAPA interaction with a norovirus protein that functionally mimics host FFAT motifs is important for murine norovirus replication. IMPORTANCE Human noroviruses are a leading cause of gastroenteritis worldwide, but host factors involved in norovirus replication are incompletely understood. Murine noroviruses have been studied to define mechanisms of norovirus replication. Here we defined the importance of the interaction between the hitherto poorly studied NS1/2 norovirus protein and the

Genetic manipulation of endosymbionts to control vector and vector borne diseases

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Jay Prakash Gupta

Full Text Available Vector borne diseases (VBD are on the rise because of failure of the existing methods of control of vector and vector borne diseases and the climate change. A steep rise of VBDs are due to several factors like selection of insecticide resistant vector population, drug resistant parasite population and lack of effective vaccines against the VBDs. Environmental pollution, public health hazard and insecticide resistant vector population indicate that the insecticides are no longer a sustainable control method of vector and vector-borne diseases. Amongst the various alternative control strategies, symbiont based approach utilizing endosymbionts of arthropod vectors could be explored to control the vector and vector borne diseases. The endosymbiont population of arthropod vectors could be exploited in different ways viz., as a chemotherapeutic target, vaccine target for the control of vectors. Expression of molecules with antiparasitic activity by genetically transformed symbiotic bacteria of disease-transmitting arthropods may serve as a powerful approach to control certain arthropod-borne diseases. Genetic transformation of symbiotic bacteria of the arthropod vector to alter the vector’s ability to transmit pathogen is an alternative means of blocking the transmission of VBDs. In Indian scenario, where dengue, chikungunya, malaria and filariosis are prevalent, paratransgenic based approach can be used effectively. [Vet World 2012; 5(9.000: 571-576

Prediction of endoplasmic reticulum resident proteins using fragmented amino acid composition and support vector machine

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Ravindra Kumar

2017-09-01

Full Text Available Background The endoplasmic reticulum plays an important role in many cellular processes, which includes protein synthesis, folding and post-translational processing of newly synthesized proteins. It is also the site for quality control of misfolded proteins and entry point of extracellular proteins to the secretory pathway. Hence at any given point of time, endoplasmic reticulum contains two different cohorts of proteins, (i proteins involved in endoplasmic reticulum-specific function, which reside in the lumen of the endoplasmic reticulum, called as endoplasmic reticulum resident proteins and (ii proteins which are in process of moving to the extracellular space. Thus, endoplasmic reticulum resident proteins must somehow be distinguished from newly synthesized secretory proteins, which pass through the endoplasmic reticulum on their way out of the cell. Approximately only 50% of the proteins used in this study as training data had endoplasmic reticulum retention signal, which shows that these signals are not essentially present in all endoplasmic reticulum resident proteins. This also strongly indicates the role of additional factors in retention of endoplasmic reticulum-specific proteins inside the endoplasmic reticulum. Methods This is a support vector machine based method, where we had used different forms of protein features as inputs for support vector machine to develop the prediction models. During training leave-one-out approach of cross-validation was used. Maximum performance was obtained with a combination of amino acid compositions of different part of proteins. Results In this study, we have reported a novel support vector machine based method for predicting endoplasmic reticulum resident proteins, named as ERPred. During training we achieved a maximum accuracy of 81.42% with leave-one-out approach of cross-validation. When evaluated on independent dataset, ERPred did prediction with sensitivity of 72.31% and specificity of 83

The Xanthomonas campestris type III effector XopJ targets the host cell proteasome to suppress salicylic-acid mediated plant defence.

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Suayib Üstün

Full Text Available The phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv requires type III effector proteins (T3Es for virulence. After translocation into the host cell, T3Es are thought to interact with components of host immunity to suppress defence responses. XopJ is a T3E protein from Xcv that interferes with plant immune responses; however, its host cellular target is unknown. Here we show that XopJ interacts with the proteasomal subunit RPT6 in yeast and in planta to inhibit proteasome activity. A C235A mutation within the catalytic triad of XopJ as well as a G2A exchange within the N-terminal myristoylation motif abolishes the ability of XopJ to inhibit the proteasome. Xcv ΔxopJ mutants are impaired in growth and display accelerated symptom development including tissue necrosis on susceptible pepper leaves. Application of the proteasome inhibitor MG132 restored the ability of the Xcv ΔxopJ to attenuate the development of leaf necrosis. The XopJ dependent delay of tissue degeneration correlates with reduced levels of salicylic acid (SA and changes in defence- and senescence-associated gene expression. Necrosis upon infection with Xcv ΔxopJ was greatly reduced in pepper plants with reduced expression of NPR1, a central regulator of SA responses, demonstrating the involvement of SA-signalling in the development of XopJ dependent phenotypes. Our results suggest that XopJ-mediated inhibition of the proteasome interferes with SA-dependent defence response to attenuate onset of necrosis and to alter host transcription. A central role of the proteasome in plant defence is discussed.

Drivers for the emergence and re-emergence of vector-borne protozoal and bacterial diseases.

Science.gov (United States)

Harrus, S; Baneth, G

2005-10-01

In recent years, vector-borne parasitic and bacterial diseases have emerged or re-emerged in many geographical regions causing global health and economic problems that involve humans, livestock, companion animals and wild life. The ecology and epidemiology of vector-borne diseases are affected by the interrelations between three major factors comprising the pathogen, the host (human, animal or vector) and the environment. Important drivers for the emergence and spread of vector-borne parasites include habitat changes, alterations in water storage and irrigation habits, atmospheric and climate changes, immunosuppression by HIV, pollution, development of insecticide and drug resistance, globalization and the significant increase in international trade, tourism and travel. War and civil unrest, and governmental or global management failure are also major contributors to the spread of infectious diseases. The improvement of epidemic understanding and planning together with the development of new diagnostic molecular techniques in the last few decades have allowed researchers to better diagnose and trace pathogens, their origin and routes of infection, and to develop preventive public health and intervention programs. Health care workers, physicians, veterinarians and biosecurity officers should play a key role in future prevention of vector-borne diseases. A coordinated global approach for the prevention of vector-borne diseases should be implemented by international organizations and governmental agencies in collaboration with research institutions.

Vector-vector production in photon-photon interactions

International Nuclear Information System (INIS)

Ronan, M.T.

1988-01-01

Measurements of exclusive untagged /rho/ 0 /rho/ 0 , /rho//phi/, K/sup *//bar K//sup */, and /rho/ω production and tagged /rho/ 0 /rho/ 0 production in photon-photon interactions by the TPC/Two-Gamma experiment are reviewed. Comparisons to the results of other experiments and to models of vector-vector production are made. Fits to the data following a four quark model prescription for vector meson pair production are also presented. 10 refs., 9 figs

An invasive mammal (the gray squirrel, Sciurus carolinensis) commonly hosts diverse and atypical genotypes of the zoonotic pathogen Borrelia burgdorferi sensu lato

DEFF Research Database (Denmark)

Millins, Caroline; Magierecka, Agnieszka; Gilbert, Lucy

2015-01-01

and may support host specific strains. This study examined the role of grey squirrels (Sciurus carolinensis), (n=679), an invasive species in the United Kingdom (UK), as B. burgdorferi s.l. hosts. We found that grey squirrels were frequently infested with Ixodes ricinus, the main vector of B. burgdorferi...

The abundance and host-seeking behavior of culicine species (Diptera: Culicidae and Anopheles sinensis in Yongcheng city, people's Republic of China

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Liu Xiao-Bo

2011-11-01

Full Text Available Abstract Background The knowledge of mosquito species diversity and the level of anthropophily exhibited by each species in a region are of great importance to the integrated vector control. Culicine species are the primary vectors of Japanese encephalitis (JE virus and filariasis in China. Anopheles sinensis plays a major role in the maintenance of Plasmodium vivax malaria transmission in China. The goal of this study was to compare the abundance and host-seeking behavior of culicine species and An. sinensis in Yongcheng city, a representative region of P. vivax malaria. Specifically, we wished to determine the relative attractiveness of different animal baits versus human bait to culicine species and An. sinensis. Results Culex tritaeniorhynchus was the most prevalent mosquito species and An. sinensis was the sole potential vector of P. vivax malaria in Yongcheng city. There were significant differences (P An. sinensis and Cx. tritaeniorhynchus collected in distinct baited traps. The relative attractiveness of animal versus human bait was similar towards both An. sinensis and Cx. tritaeniorhynchus. The ranking derived from the mean number of mosquitoes per bait indicated that pigs, goats and calves frequently attracted more mosquitoes than the other hosts tested (dogs, humans, and chickens. These trends were similar across all capture nights at three distinct villages. The human blood index (HBI of female An. sinensis was 2.94% when computed with mixed meals while 3.70% computed with only the single meal. 19:00~21:00 was the primary peak of host-seeking female An. sinensis while 4:00~5:00 was the smaller peak at night. There was significant correlation between the density of female An. sinensis and the average relative humidity (P Conclusions Pigs, goats and calves were more attractive to An. sinensis and Cx. tritaeniorhynchus than dogs, humans, and chickens. Female An. sinensis host-seeking activity mainly occurred from 19:00 to 21:00. Thus

Host age modulates within-host parasite competition.

Science.gov (United States)

Izhar, Rony; Routtu, Jarkko; Ben-Ami, Frida

2015-05-01

In many host populations, one of the most striking differences among hosts is their age. While parasite prevalence differences in relation to host age are well known, little is known on how host age impacts ecological and evolutionary dynamics of diseases. Using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa, we examined how host age at exposure influences within-host parasite competition and virulence. We found that multiply-exposed hosts were more susceptible to infection and suffered higher mortality than singly-exposed hosts. Hosts oldest at exposure were least often infected and vice versa. Furthermore, we found that in young multiply-exposed hosts competition was weak, allowing coexistence and transmission of both parasite clones, whereas in older multiply-exposed hosts competitive exclusion was observed. Thus, age-dependent parasite exposure and host demography (age structure) could together play an important role in mediating parasite evolution. At the individual level, our results demonstrate a previously unnoticed interaction of the host's immune system with host age, suggesting that the specificity of immune function changes as hosts mature. Therefore, evolutionary models of parasite virulence might benefit from incorporating age-dependent epidemiological parameters. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Host-feeding pattern of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in heterogeneous landscapes of South Andaman, Andaman and Nicobar Islands, India.

Science.gov (United States)

Sivan, Arun; Shriram, A N; Sunish, I P; Vidhya, P T

2015-09-01

Mosquito foraging behavior is a determinant of host-vector contact and has an impact on the risk of arboviral epidemics. Therefore, blood-feeding patterns is a useful tool for assessing the role in pathogen transmission by vector mosquitoes. Competent vectors of dengue and chikungunya viz. Aedes aegypti and Aedes albopictus are widely prevalent in the Andaman and Nicobar archipelago. Considering the vector potential, medical importance of both these mosquito species and lack of information on host-feeding patterns, blood meal analysis of both these vector mosquitoes was undertaken. Biogents Sentinel traps were used for sampling blooded mosquitoes, for identifying the source of blood meal by agar gel-precipitin test. We identified vertebrate source of 147 and 104 blood meals in Ae. aegypti and Ae. albopictus from heterogeneous landscapes in South Andaman district. Results revealed that Ae. aegypti (88 %) and Ae. albopictus (49 %) fed on human and a small proportion on mammals and fowls, indicative of predominance of anthropophilism. Ae. aegypti predominantly fed on human blood (94.2 %-densely built urban, 89.8 %-low vegetation coverage, and 78.3 %-medium vegetation coverage). Anthropophilism in Ae. albopictus was maximal in densely built urban (90.5 %) and progressively decreased from low vegetation-vegetation/forested continuum (66.7, 36.4, and 8.7 %), indicating plasticity in feeding across these landscapes. Epidemiological significance of the findings is discussed.

Host outdoor exposure variability affects the transmission and spread of Zika virus: Insights for epidemic control.

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Marco Ajelli

2017-09-01

Full Text Available Zika virus transmission dynamics in urban environments follow a complex spatiotemporal pattern that appears unpredictable and barely related to high mosquito density areas. In this context, human activity patterns likely have a major role in Zika transmission dynamics. This paper examines the effect of host variability in the amount of time spent outdoors on Zika epidemiology in an urban environment.First, we performed a survey on time spent outdoors by residents of Miami-Dade County, Florida. Second, we analyzed both the survey and previously published national data on outdoors time in the U.S. to provide estimates of the distribution of the time spent outdoors. Third, we performed a computational modeling evaluation of Zika transmission dynamics, based on the time spent outdoors by each person. Our analysis reveals a strong heterogeneity of the host population in terms of time spent outdoors-data are well captured by skewed gamma distributions. Our model-based evaluation shows that in a heterogeneous population, Zika would cause a lower number of infections than in a more homogenous host population (up to 4-fold differences, but, at the same time, the epidemic would spread much faster. We estimated that in highly heterogeneous host populations the timing of the implementation of vector control measures is the major factor for limiting the number of Zika infections.Our findings highlight the need of considering host variability in exposure time for managing mosquito-borne infections and call for the revision of the triggers for vector control strategies, which should integrate mosquito density data and human outdoor activity patterns in specific areas.

The Role of Microbial Amino Acid Metabolism in Host Metabolism

OpenAIRE

Evelien P. J. G. Neis; Cornelis H. C. Dejong; Sander S. Rensen

2015-01-01

Disruptions in gut microbiota composition and function are increasingly implicated in the pathogenesis of obesity, insulin resistance, and type 2 diabetes mellitus. The functional output of the gut microbiota, including short-chain fatty acids and amino acids, are thought to be important modulators underlying the development of these disorders. Gut bacteria can alter the bioavailability of amino acids by utilization of several amino acids originating from both alimentary and endogenous protei...