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Zakhia R, Dupuis AP, Khodr F, Fadel M, Kramer LD, Haddad N. Evidence of West Nile Virus Circulation in Lebanon. Viruses 2021; 13:v13060994. [PMID: 34073485 PMCID: PMC8227205 DOI: 10.3390/v13060994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/27/2021] [Accepted: 05/03/2021] [Indexed: 12/16/2022] Open
Abstract
West Nile virus (WNV) has never been reported from Lebanon. Yet, this country is located on the flyway of migratory birds in the Middle East region. Serological screening was conducted to assess the potential circulation of this virus. Human, horse, and chicken sera were collected from the Bekaa and North districts. Specific IgG and IgY were first screened by ELISA. Then, positive samples were confirmed by plaque reduction neutralization test (PRNT). Besides this, adult mosquitoes were collected and tested for the presence of WNV RNA using conventional RT-PCR. Sera screening revealed a seroprevalence rate reaching 1.86% among humans and 2.47% among horses. Cross-reactions revealed by ELISA suggested the circulation of flaviviruses other than WNV. None of the tested mosquitoes was positive for WNV. The observed results constitute strong evidence of local exposure of the Lebanese population to this virus and the first report of equine WNV in Lebanon.
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Affiliation(s)
- Renée Zakhia
- Laboratory of Immunology and Vector-Borne Diseases, Faculty of Public Health, Lebanese University, Fanar 6573/14, Lebanon; (R.Z.); (F.K.); (M.F.)
| | - Alan P. Dupuis
- Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Albany, NY 12159, USA; (A.P.D.II); (L.D.K.)
| | - Fayçal Khodr
- Laboratory of Immunology and Vector-Borne Diseases, Faculty of Public Health, Lebanese University, Fanar 6573/14, Lebanon; (R.Z.); (F.K.); (M.F.)
| | - Mahdi Fadel
- Laboratory of Immunology and Vector-Borne Diseases, Faculty of Public Health, Lebanese University, Fanar 6573/14, Lebanon; (R.Z.); (F.K.); (M.F.)
| | - Laura D. Kramer
- Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Albany, NY 12159, USA; (A.P.D.II); (L.D.K.)
- Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, NY 12201, USA
| | - Nabil Haddad
- Laboratory of Immunology and Vector-Borne Diseases, Faculty of Public Health, Lebanese University, Fanar 6573/14, Lebanon; (R.Z.); (F.K.); (M.F.)
- Correspondence:
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Dellicour S, Lequime S, Vrancken B, Gill MS, Bastide P, Gangavarapu K, Matteson NL, Tan Y, du Plessis L, Fisher AA, Nelson MI, Gilbert M, Suchard MA, Andersen KG, Grubaugh ND, Pybus OG, Lemey P. Epidemiological hypothesis testing using a phylogeographic and phylodynamic framework. Nat Commun 2020; 11:5620. [PMID: 33159066 PMCID: PMC7648063 DOI: 10.1038/s41467-020-19122-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 09/30/2020] [Indexed: 01/05/2023] Open
Abstract
Computational analyses of pathogen genomes are increasingly used to unravel the dispersal history and transmission dynamics of epidemics. Here, we show how to go beyond historical reconstructions and use spatially-explicit phylogeographic and phylodynamic approaches to formally test epidemiological hypotheses. We illustrate our approach by focusing on the West Nile virus (WNV) spread in North America that has substantially impacted public, veterinary, and wildlife health. We apply an analytical workflow to a comprehensive WNV genome collection to test the impact of environmental factors on the dispersal of viral lineages and on viral population genetic diversity through time. We find that WNV lineages tend to disperse faster in areas with higher temperatures and we identify temporal variation in temperature as a main predictor of viral genetic diversity through time. By contrasting inference with simulation, we find no evidence for viral lineages to preferentially circulate within the same migratory bird flyway, suggesting a substantial role for non-migratory birds or mosquito dispersal along the longitudinal gradient.
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Affiliation(s)
- Simon Dellicour
- Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles, CP160/12, 50 Avenue FD Roosevelt, 1050, Bruxelles, Belgium.
- Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Herestraat 49, 3000, Leuven, Belgium.
| | - Sebastian Lequime
- Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Bram Vrancken
- Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Mandev S Gill
- Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Paul Bastide
- Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Karthik Gangavarapu
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Nathaniel L Matteson
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Yi Tan
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Infectious Diseases Group, J. Craig Venter Institute, Rockville, MD, USA
| | | | - Alexander A Fisher
- Department of Biomathematics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Martha I Nelson
- Fogarty International Center, National Institutes of Health, Bethesda, MD, 20894, USA
| | - Marius Gilbert
- Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles, CP160/12, 50 Avenue FD Roosevelt, 1050, Bruxelles, Belgium
| | - Marc A Suchard
- Department of Biomathematics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Department of Biostatistics, Fielding School of Public Health, University of California, Los Angeles, CA, USA
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Kristian G Andersen
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
- Scripps Research Translational Institute, La Jolla, CA, 92037, USA
| | - Nathan D Grubaugh
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, 06510, USA
| | | | - Philippe Lemey
- Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
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Ukawuba I, Shaman J. Association of spring-summer hydrology and meteorology with human West Nile virus infection in West Texas, USA, 2002-2016. Parasit Vectors 2018; 11:224. [PMID: 29618375 PMCID: PMC5885460 DOI: 10.1186/s13071-018-2781-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 03/06/2018] [Indexed: 11/30/2022] Open
Abstract
Background The emergence of West Nile virus (WNV) in the Western Hemisphere has motivated research into the processes contributing to the incidence and persistence of the disease in the region. Meteorology and hydrology are fundamental determinants of vector-borne disease transmission dynamics of a region. The availability of water influences the population dynamics of vector and host, while temperature impacts vector growth rates, feeding habits, and disease transmission potential. Characterization of the temporal pattern of environmental factors influencing WNV risk is crucial to broaden our understanding of local transmission dynamics and to inform efforts of control and surveillance. Methods We used hydrologic, meteorological and WNV data from west Texas (2002–2016) to analyze the relationship between environmental conditions and annual human WNV infection. A Bayesian model averaging framework was used to evaluate the association of monthly environmental conditions with WNV infection. Results Findings indicate that wet conditions in the spring combined with dry and cool conditions in the summer are associated with increased annual WNV cases. Bayesian multi-model inference reveals monthly means of soil moisture, specific humidity and temperature to be the most important variables among predictors tested. Environmental conditions in March, June, July and August were the leading predictors in the best-fitting models. Conclusions The results significantly link soil moisture and temperature in the spring and summer to WNV transmission risk. Wet spring in association with dry and cool summer was the temporal pattern best-describing WNV, regardless of year. Our findings also highlight that soil moisture may be a stronger predictor of annual WNV transmission than rainfall.
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Affiliation(s)
- Israel Ukawuba
- Mailman School of Public Health, Columbia University, 722 W 168th, New York, NY, 10032, USA.
| | - Jeffrey Shaman
- Mailman School of Public Health, Columbia University, 722 W 168th, New York, NY, 10032, USA
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Nelms BM, Thiemann TC, Bridges DN, Williams AE, Koschik ML, Ryan BM, Scott JJ. Bionomics and Vector Potential of Culex thriambus (Diptera: Culicidae) Mosquitoes in Lake County, California. JOURNAL OF MEDICAL ENTOMOLOGY 2016; 53:1473-1481. [PMID: 27493251 PMCID: PMC5106824 DOI: 10.1093/jme/tjw123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/14/2016] [Indexed: 06/06/2023]
Abstract
California statewide West Nile virus (WNV) minimum infection rates in Culex thriambus Dyar mosquitoes are high; however, few specimens are submitted and tested each year, as their distribution seems limited to larval habitats along riparian systems. To evaluate the role of Cx. thriambus in the amplification, maintenance, and overwintering of WNV in Lake County, CA, the bionomics and vector potential of the species was investigated during 2014 and 2015. Culex thriambus was the most abundant mosquito species, with 1,153 adults and 7,624 immatures collected by vacuum aspiration and dip sampling, respectively, at the primary study site. Detection of WNV in four mosquito pools during September through November coincided with peak seasonality. Females entered and maintained a reproductive diapause during winter under field and seminatural conditions. Diapause was initiated in the majority of Cx. thriambus females by October and was terminated by 30 March. Some parous females (7.1%) and those in host-seeking arrest (7.1%) were collected throughout the winter period. An accrual of 679.51 degree-days (°D) was necessary for diapause termination under seminatural conditions. Culex thriambus females fed on 16 different avian species during spring and summer, and no mammalian feeds were detected. West Nile viral RNA was detected in four of 42 Cx. thriambus pools tested during June through November and infection rates ranged from 3.53-28.15/1,000 tested. In summary, WNV transmission may be increased along riparian corridors throughout California where Cx. thriambus mosquitoes remain relatively abundant.
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Affiliation(s)
- Brittany M Nelms
- Lake County Vector Control District, 410 Esplanade St., Lakeport, CA 95453 (; ; ; ; )
| | - Tara C Thiemann
- University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211 (; )
| | - Danielle N Bridges
- Lake County Vector Control District, 410 Esplanade St., Lakeport, CA 95453 (; ; ; ; )
| | - Alan E Williams
- University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211 (; )
| | - Michelle L Koschik
- Lake County Vector Control District, 410 Esplanade St., Lakeport, CA 95453 (; ; ; ; )
| | - Bonnie M Ryan
- Lake County Vector Control District, 410 Esplanade St., Lakeport, CA 95453 (; ; ; ; )
| | - Jamesina J Scott
- Lake County Vector Control District, 410 Esplanade St., Lakeport, CA 95453 (; ; ; ; )
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5
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Staley M, Bonneaud C. Immune responses of wild birds to emerging infectious diseases. Parasite Immunol 2015; 37:242-54. [PMID: 25847450 DOI: 10.1111/pim.12191] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 03/31/2015] [Indexed: 12/17/2022]
Abstract
Over the past several decades, outbreaks of emerging infectious diseases (EIDs) in wild birds have attracted worldwide media attention, either because of their extreme virulence or because of alarming spillovers into agricultural animals or humans. The pathogens involved have been found to infect a variety of bird hosts ranging from relatively few species (e.g. Trichomonas gallinae) to hundreds of species (e.g. West Nile Virus). Here we review and contrast the immune responses that wild birds are able to mount against these novel pathogens. We discuss the extent to which these responses are associated with reduced clinical symptoms, pathogen load and mortality, or conversely, how they can be linked to worsened pathology and reduced survival. We then investigate how immune responses to EIDs can evolve over time in response to pathogen-driven selection using the illustrative case study of the epizootic outbreak of Mycoplasma gallisepticum in wild North American house finches (Haemorhous mexicanus). We highlight the need for future work to take advantage of the substantial inter- and intraspecific variation in disease progression and outcome following infections with EID to elucidate the extent to which immune responses confer increased resistance through pathogen clearance or may instead heighten pathogenesis.
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Affiliation(s)
- M Staley
- Department of Biological Sciences, Auburn University, Auburn, AL, USA
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6
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Vector-virus interactions and transmission dynamics of West Nile virus. Viruses 2013; 5:3021-47. [PMID: 24351794 PMCID: PMC3967159 DOI: 10.3390/v5123021] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 11/04/2013] [Accepted: 11/06/2013] [Indexed: 12/17/2022] Open
Abstract
West Nile virus (WNV; Flavivirus; Flaviviridae) is the cause of the most widespread arthropod-borne viral disease in the world and the largest outbreak of neuroinvasive disease ever observed. Mosquito-borne outbreaks are influenced by intrinsic (e.g., vector and viral genetics, vector and host competence, vector life-history traits) and extrinsic (e.g., temperature, rainfall, human land use) factors that affect virus activity and mosquito biology in complex ways. The concept of vectorial capacity integrates these factors to address interactions of the virus with the arthropod host, leading to a clearer understanding of their complex interrelationships, how they affect transmission of vector-borne disease, and how they impact human health. Vertebrate factors including host competence, population dynamics, and immune status also affect transmission dynamics. The complexity of these interactions are further exacerbated by the fact that not only can divergent hosts differentially alter the virus, but the virus also can affect both vertebrate and invertebrate hosts in ways that significantly alter patterns of virus transmission. This chapter concentrates on selected components of the virus-vector-vertebrate interrelationship, focusing specifically on how interactions between vector, virus, and environment shape the patterns and intensity of WNV transmission.
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Baldacchino F, Muenworn V, Desquesnes M, Desoli F, Charoenviriyaphap T, Duvallet G. Transmission of pathogens by Stomoxys flies (Diptera, Muscidae): a review. ACTA ACUST UNITED AC 2013; 20:26. [PMID: 23985165 PMCID: PMC3756335 DOI: 10.1051/parasite/2013026] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 08/13/2013] [Indexed: 12/02/2022]
Abstract
Stomoxys flies are mechanical vectors of pathogens present in the blood and skin of their animal hosts, especially livestock, but occasionally humans. In livestock, their direct effects are disturbance, skin lesions, reduction of food intake, stress, blood loss, and a global immunosuppressive effect. They also induce the gathering of animals for mutual protection; meanwhile they favor development of pathogens in the hosts and their transmission. Their indirect effect is the mechanical transmission of pathogens. In case of interrupted feeding, Stomoxys can re-start their blood meal on another host. When injecting saliva prior to blood-sucking, they can inoculate some infected blood remaining on their mouthparts. Beside this immediate transmission, it was observed that Stomoxys may keep some blood in their crop, which offers a friendly environment for pathogens that could be regurgitated during the next blood meal; thus a delayed transmission by Stomoxys seems possible. Such a mechanism has a considerable epidemiological impact since it allows inter-herd transmission of pathogens. Equine infectious anemia, African swine fever, West Nile, and Rift Valley viruses are known to be transmitted by Stomoxys, while others are suspected. Rickettsia (Anaplasma, Coxiella), other bacteria and parasites (Trypanosoma spp., Besnoitia spp.) are also transmitted by Stomoxys. Finally, Stomoxys was also found to act as an intermediate host of the helminth Habronema microstoma and may be involved in the transmission of some Onchocerca and Dirofilaria species. Being cosmopolite, Stomoxys calcitrans might have a worldwide and greater impact than previously thought on animal and human pathogen transmission.
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Affiliation(s)
- Frédéric Baldacchino
- Centre d'Écologie Fonctionnelle et Évolutive (UMR 5175), Université Montpellier 3, Route de Mende, 34199 Montpellier Cedex 5, France
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Tomerini DM, Dale PE, Sipe N. Does mosquito control have an effect on mosquito-borne disease? The case of Ross River virus disease and mosquito management in Queensland, Australia. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2011; 27:39-44. [PMID: 21476446 DOI: 10.2987/10-6038.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We examined the relationship between types of mosquito control programs and the mosquito-borne Ross River virus (RRV) disease in Queensland, Australia. Mosquito control information was collected through a survey of the responsible agencies (local governments), and RRV disease notification data were provided by the Queensland state health authority. The study developed a typology of mosquito control programs, based on the approaches used. Based on the analysis of data on RRV disease rates between mosquito control types within 4 climatic regions, each region had different combinations of mosquito control strategies in their programs; there were also general similarities in the relationship between program types and RRV rates between the regions. The long-term RRV disease rates were lower in areas where the mosquito control program included pre-emptive (rather than reactive) surveillance based on an extensive (rather than incomplete) knowledge of mosquito habitats, and where treatment of both saltwater and freshwater habitats (compared to only saltwater habitats, in coastal areas) occurred. The data indicate that mosquito control is an effective public health intervention to reduce mosquito-borne disease; hence, climate change adaptation strategies should ensure that adequate resources are available for effective vector control so as to manage the risk of mosquito-borne diseases.
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Affiliation(s)
- Deanna M Tomerini
- Urban Research Program, Griffith School of Environment, Griffith University, Nathan, Queensland, Australia, 4111
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Harrigan RJ, Thomassen HA, Buermann W, Cummings RF, Kahn ME, Smith TB. Economic conditions predict prevalence of West Nile virus. PLoS One 2010; 5:e15437. [PMID: 21103053 PMCID: PMC2980475 DOI: 10.1371/journal.pone.0015437] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 09/21/2010] [Indexed: 12/26/2022] Open
Abstract
Understanding the conditions underlying the proliferation of infectious diseases is crucial for mitigating future outbreaks. Since its arrival in North America in 1999, West Nile virus (WNV) has led to population-wide declines of bird species, morbidity and mortality of humans, and expenditures of millions of dollars on treatment and control. To understand the environmental conditions that best explain and predict WNV prevalence, we employed recently developed spatial modeling techniques in a recognized WNV hotspot, Orange County, California. Our models explained 85–95% of the variation of WNV prevalence in mosquito vectors, and WNV presence in secondary human hosts. Prevalence in both vectors and humans was best explained by economic variables, specifically per capita income, and by anthropogenic characteristics of the environment, particularly human population and neglected swimming pool density. While previous studies have shown associations between anthropogenic change and pathogen presence, results show that poorer economic conditions may act as a direct surrogate for environmental characteristics related to WNV prevalence. Low-income areas may be associated with higher prevalence for a number of reasons, including variations in property upkeep, microhabitat conditions conducive to viral amplification in both vectors and hosts, host community composition, and human behavioral responses related to differences in education or political participation. Results emphasize the importance and utility of including economic variables in mapping spatial risk assessments of disease.
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Affiliation(s)
- Ryan J Harrigan
- Center for Tropical Research, Institute of the Environment, University of California Los Angeles, Los Angeles, California, United States of America.
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Ricklefs RE. Host-pathogen coevolution, secondary sympatry and species diversification. Philos Trans R Soc Lond B Biol Sci 2010; 365:1139-47. [PMID: 20194175 DOI: 10.1098/rstb.2009.0279] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The build-up of species locally within a region by allopatric speciation depends on geographically separated (allopatric) sister populations becoming reproductively incompatible followed by secondary sympatry. Among birds, this has happened frequently in remote archipelagos, spectacular cases including the Darwin's finches (Geospizinae) and Hawaiian honeycreepers (Drepanidinae), but similar examples are lacking in archipelagos nearer to continental landmasses. Of the required steps in the speciation cycle, achievement of secondary sympatry appears to be limiting in near archipelagos and, by extension, in continental regions. Here, I suggest that secondary sympatry might be prevented by apparent competition mediated through pathogens that are locally coevolved with one population of host and are pathogenic in sister populations. The absence of numerous pathogens in remote archipelagos might, therefore, allow sister populations to achieve secondary sympatry more readily and thereby accelerate diversification. By similar reasoning, species should accumulate relatively slowly within continental regions. In this essay, I explore the assumptions and some implications of this model for species diversification.
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Affiliation(s)
- Robert E Ricklefs
- Department of Biology, University of Missouri-St Louis, One University Boulevard, St Louis, MO 63121-4499, USA.
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Rochlin I, Dempsey ME, Campbell SR, Ninivaggi DV. Salt marsh as Culex salinarius larval habitat in coastal New York. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2008; 24:359-367. [PMID: 18939687 DOI: 10.2987/5748.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Culex salinarius is considered one of the most likely bridge vectors involved in the human transmission cycle of West Nile virus (WNV) and eastern equine encephalomyelitis virus (EEEV) in the northeastern USA. The larval habitats of this species in the coastal region of New York State are currently poorly known. Between 2005 and 2007, a larval survey was carried out to identify and characterize possible larval habitats in Suffolk County, encompassing natural and man-made freshwater wetlands, artificial containers, and salt marshes. Only relatively undisturbed salt marsh yielded Cx. salinarius larvae in considerable numbers from several sites over a period of 2 years. The immature stages of this species were found associated with Spartina patens and S. alterniflora of the upper marsh at salinities ranging from 4.3 to 18.8 parts per thousand. Both heavily impacted and relatively undisturbed salt marshes produced several hundreds of adult Cx. salinarius per Centers for Disease Control and Prevention (CDC) light trap per night, an order of magnitude higher than CDC light traps deployed at upland sites. The ability of Cx. salinarius to use both heavily impacted and relatively undisturbed salt marshes for reproduction has significant repercussions for marsh restoration and vector control practices.
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Affiliation(s)
- Ilia Rochlin
- Division of Vector Control, Suffolk County Department of Public Works, 335 Yaphank Ave., Yaphank, NY 11980-9744, USA
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13
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Epp T, Waldner C, Townsend HGG. A case-control study of factors associated with development of clinical disease due to West Nile virus, Saskatchewan 2003. Equine Vet J 2008; 39:498-503. [PMID: 18065306 DOI: 10.2746/042516407x248476] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASON FOR PERFORMING STUDY West Nile virus (WNV) was first diagnosed in Saskatchewan equids in 2002. AWNV epidemic was considered highly likely for 2003, which would provide a unique opportunity to study all aspects of WNV subclinical infection and clinical disease development in a relatively naive population. HYPOTHESIS There are individual equid attributes and management risk factors associated with development of clinical disease. Specifically, this study could address the question of vaccine efficacy for the prevention of development of clinical disease. METHODS A case-control study was conducted in the summer of 2003 during a province-wide outbreak of WNV. Between 5 and 10 equids were sampled from each of 23 case premises with clinical disease and 23 control premises with no apparent or confirmed clinical disease. Data were analysed to identify risk factors for the development of clinical disease. RESULTS The proportion of equids serologically positive for natural exposure to West Nile virus was 64% (193/300). Nonvaccinated equids were 23 times (95%CI limits 3.0, 168.5, P = 0.002) more likely to develop clinical disease than those vaccinated. The estimate of vaccine efficacy in this field study was 96% (95%CI limits 67%, 99%). CONCLUSIONS The study demonstrated that vaccination was strongly associated with the prevention of clinical disease. POTENTIAL RELEVANCE Vaccination is an effective, practical method of prevention of clinical disease.
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Affiliation(s)
- T Epp
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada
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Brault AC, Huang CYH, Langevin SA, Kinney RM, Bowen RA, Ramey WN, Panella NA, Holmes EC, Powers AM, Miller BR. A single positively selected West Nile viral mutation confers increased virogenesis in American crows. Nat Genet 2007; 39:1162-6. [PMID: 17694056 PMCID: PMC2291521 DOI: 10.1038/ng2097] [Citation(s) in RCA: 264] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Accepted: 06/08/2007] [Indexed: 12/11/2022]
Abstract
West Nile virus (WNV), first recognized in North America in 1999, has been responsible for the largest arboviral epiornitic and epidemic of human encephalitis in recorded history. Despite the well-described epidemiological patterns of WNV in North America, the basis for the emergence of WNV-associated avian pathology, particularly in the American crow (AMCR) sentinel species, and the large scale of the North American epidemic and epiornitic is uncertain. We report here that the introduction of a T249P amino acid substitution in the NS3 helicase (found in North American WNV) in a low-virulence strain was sufficient to generate a phenotype highly virulent to AMCRs. Furthermore, comparative sequence analyses of full-length WNV genomes demonstrated that the same site (NS3-249) was subject to adaptive evolution. These phenotypic and evolutionary results provide compelling evidence for the positive selection of a mutation encoding increased viremia potential and virulence in the AMCR sentinel bird species.
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Affiliation(s)
- Aaron C Brault
- Center for Vector-Borne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California 95616, USA.
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15
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Ciota AT, Ngo KA, Lovelace AO, Payne AF, Zhou Y, Shi PY, Kramer LD. Role of the mutant spectrum in adaptation and replication of West Nile virus. J Gen Virol 2007; 88:865-874. [PMID: 17325359 PMCID: PMC3249657 DOI: 10.1099/vir.0.82606-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
West Nile virus (WNV) has successfully spread throughout the USA, Canada, Mexico, the Caribbean and parts of Central and South America since its 1999 introduction into North America. Despite infecting a broad range of both mosquito and avian species, the virus remains highly genetically conserved. This lack of evolutionary change over space and time is common with many arboviruses and is frequently attributed to the adaptive constraints resulting from the virus cycling between vertebrate hosts and invertebrate vectors. WNV, like most RNA viruses studied thus far, has been shown in nature to exist as a highly genetically diverse population of genotypes. Few studies have directly evaluated the role of these mutant spectra in viral fitness and adaptation. Using clonal analysis and reverse genetics experiments, this study evaluated genotype diversity and the importance of consensus change in producing the adaptive phenotype of WNV following sequential mosquito cell passage. The results indicated that increases in the replicative ability of WNV in mosquito cells correlate with increases in the size of the mutant spectrum, and that consensus change is not solely responsible for alterations in viral fitness and adaptation of WNV. These data provide evidence of the importance of quasispecies dynamics in the adaptation of a flavivirus to new and changing environments and hosts, with little evidence of significant genetic change.
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Affiliation(s)
- Alexander T. Ciota
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Kiet A. Ngo
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Amy O. Lovelace
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Anne F. Payne
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Yangsheng Zhou
- Department of Biomedical Sciences, University at Albany, State University of New York, Albany, NY 12201, USA
| | - Pei-Yong Shi
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
- Department of Biomedical Sciences, University at Albany, State University of New York, Albany, NY 12201, USA
| | - Laura D. Kramer
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
- Department of Biomedical Sciences, University at Albany, State University of New York, Albany, NY 12201, USA
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16
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Abstract
Emerging viral infections are becoming a serious problem in Europe in the recent years. This is particularly true for severe acute respiratory syndrome (SARS), West Nile virus (WNV) disease, Toscana virus (TOSV) disease, and potentially for avian influenza virus (H5N1). In contrast, emergence or re-emergence of severe viral infections, including tick borne encephalitis virus, and viral haemorrhagic fever caused by Hantavirus and dengue virus have been frequently reported in several European countries. Laboratory diagnosis of these viral infections based on viral isolation or detection by immune electron microscopy, immunoassay and polymerase chain reaction (PCR) has dramatically improved in the recent years, and SARS represents a good example of a diagnostic approach to emerging viral infections. Finally, old and new promising agents are in the pipeline of pharmaceutical companies to treat emerging viral infections. However only prevention based on large epidemiological studies, and research and development of new vaccines may be able to control and eventually eradicate these deadly viral infections.
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Affiliation(s)
- Agostino Pugliese
- Department of Medical and Surgical Sciences, Section of Clinical Microbiology of Turin University, Amedeo di Savoia Hospital, Turin, Italy.
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Kilpatrick AM, Daszak P, Jones MJ, Marra PP, Kramer LD. Host heterogeneity dominates West Nile virus transmission. Proc Biol Sci 2006; 273:2327-33. [PMID: 16928635 PMCID: PMC1636093 DOI: 10.1098/rspb.2006.3575] [Citation(s) in RCA: 349] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Heterogeneity in host populations and communities can have large effects on the transmission and control of a pathogen. In extreme cases, a few individuals give rise to the majority of secondary infections, which have been termed super spreading events. Here, we show that transmission of West Nile virus (WNV) is dominated by extreme heterogeneity in the host community, resulting in highly inflated reproductive ratios. A single relatively uncommon avian species, American robin (Turdus migratorius), appeared to be responsible for the majority of WNV-infectious mosquitoes and acted as the species equivalent of a super spreader for this multi-host pathogen. Crows were also highly preferred by mosquitoes at some sites, while house sparrows were significantly avoided. Nonetheless, due to their relative rarity, corvids (crows and jays) were relatively unimportant in WNV amplification. These results challenge current beliefs about the role of certain avian species in WNV amplification and demonstrate the importance of determining contact rates between vectors and host species to understand pathogen transmission dynamics.
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18
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Ciota AT, Lovelace AO, Ngo KA, Le AN, Maffei JG, Franke MA, Payne AF, Jones SA, Kauffman EB, Kramer LD. Cell-specific adaptation of two flaviviruses following serial passage in mosquito cell culture. Virology 2006; 357:165-74. [PMID: 16963095 PMCID: PMC3249649 DOI: 10.1016/j.virol.2006.08.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Revised: 06/30/2006] [Accepted: 08/03/2006] [Indexed: 10/24/2022]
Abstract
West Nile Virus (WNV) is a mosquito-borne flavivirus that was introduced into the U.S. in the New York City area in 1999. Despite its successful establishment and rapid spread in a naive environment, WNV has undergone limited evolution since its introduction. This evolutionary stability has been attributed to compromises made to permit alternating cycles of viral replication in vertebrate hosts and arthropod vectors. Outbreaks of a close relative of WNV, St. Louis encephalitis virus (SLEV), occur in the U.S. periodically and are also characterized by limited genetic change overtime. We measured both phenotypic and genotypic changes in WNV and SLEV serially passaged in mosquito cell culture in order to clarify the role of an individual host cell type in flavivirus adaptation and evolution. Genetic changes in passaged WNV and SLEV were minimal but led to increased relative fitness and replicative ability of the virus in the homologous cell line C6/36 mosquito cells. Similar increases were not measured in the heterologous cell line DF-1 avian cells. These phenotypic changes are consistent with the concept of cell-specific adaptation in flaviviruses.
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19
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Kilpatrick AM, Kramer LD, Jones MJ, Marra PP, Daszak P. West Nile virus epidemics in North America are driven by shifts in mosquito feeding behavior. PLoS Biol 2006; 4:e82. [PMID: 16494532 PMCID: PMC1382011 DOI: 10.1371/journal.pbio.0040082] [Citation(s) in RCA: 345] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2005] [Accepted: 01/18/2006] [Indexed: 11/24/2022] Open
Abstract
West Nile virus (WNV) has caused repeated large-scale human epidemics in North America since it was first detected in 1999 and is now the dominant vector-borne disease in this continent. Understanding the factors that determine the intensity of the spillover of this zoonotic pathogen from birds to humans (via mosquitoes) is a prerequisite for predicting and preventing human epidemics. We integrated mosquito feeding behavior with data on the population dynamics and WNV epidemiology of mosquitoes, birds, and humans. We show that
Culex pipiens, the dominant enzootic (bird-to-bird) and bridge (bird-to-human) vector of WNV in urbanized areas in the northeast and north-central United States, shifted its feeding preferences from birds to humans by 7-fold during late summer and early fall, coinciding with the dispersal of its preferred host (American robins,
Turdus migratorius) and the rise in human WNV infections. We also show that feeding shifts in
Cx. tarsalis amplify human WNV epidemics in Colorado and California and occur during periods of robin dispersal and migration. Our results provide a direct explanation for the timing and intensity of human WNV epidemics. Shifts in feeding from competent avian hosts early in an epidemic to incompetent humans after mosquito infection prevalences are high result in synergistic effects that greatly amplify the number of human infections of this and other pathogens. Our results underscore the dramatic effects of vector behavior in driving the transmission of zoonotic pathogens to humans.
A shift in the feeding behavior of mosquitoes from birds to mammals in late summer amplifies the number of human infections of West Nile virus in the northeast and north-central US.
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Affiliation(s)
- A Marm Kilpatrick
- The Consortium for Conservation Medicine, New York, New York, United States of America.
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20
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Ozkul A, Yildirim Y, Pinar D, Akcali A, Yilmaz V, Colak D. Serological evidence of West Nile Virus (WNV) in mammalian species in Turkey. Epidemiol Infect 2005; 134:826-9. [PMID: 16316496 PMCID: PMC2870448 DOI: 10.1017/s0950268805005492] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2005] [Indexed: 11/05/2022] Open
Abstract
In this study, the sera collected from a variety of mammalian species (ass-mules, cat, cattle, dog, horse, human and sheep) in 10 representative provinces of Turkey, were surveyed for the presence of neutralizing antibodies to West Nile virus (WNV). Overall, 1 of 40 (2.5%) ass-mules, 4 of 100 (4%) cattle, 43 of 114 (37.7%) dogs, 35 of 259 (13.5%) horses, 18 of 88 (20.4%) humans and 1 of 100 (1%) sheep, tested positive for WNV-neutralizing antibodies. The results indicate that a wide range of mammals are exposed to a West Nile-related virus and this could contribute to the long-term survival of this virus in the absence of overt disease.
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Affiliation(s)
- A Ozkul
- Ankara University, Faculty of Veterinary Medicine, Department of Virology, Diskapi, Ankara, Turkey.
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21
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Ebel GD, Rochlin I, Longacker J, Kramer LD. Culex restuans (Diptera: Culicidae) relative abundance and vector competence for West Nile Virus. JOURNAL OF MEDICAL ENTOMOLOGY 2005; 42:838-43. [PMID: 16363169 DOI: 10.1603/0022-2585(2005)042[0838:crdcra]2.0.co;2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The abundance and vector competence of Culex restuans Theobald and Culex pipiens L. were compared to determine the relative importance of these species as West Nile virus (WNV) vectors in the northeastern United States. Abundance was estimated from egg raft collections at 12 sites in Albany, Suffolk, and Richmond counties, New York, during July, August, and September 2002 and 2003. Cx. restuans was more abundant than Cx. pipiens in both urban and rural areas, comprising 86% of 1,623 egg rafts collected. Vector competence for WNV was estimated after feeding on an artificial bloodmeal and in vitro transmission assays. The vector competence of the two species for WNV was similar, but the dynamics of infection seems to be mosquito species dependent. These findings suggest an important role for Cx. restuans in WNV transmission cycles in New York.
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Affiliation(s)
- Gregory D Ebel
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, 5668 State Farm Road, Slingerlands, NY 12159, USA
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22
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Juliano SA, Lounibos LP. Ecology of invasive mosquitoes: effects on resident species and on human health. Ecol Lett 2005; 8:558-74. [PMID: 17637849 PMCID: PMC1920178 DOI: 10.1111/j.1461-0248.2005.00755] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Investigations of biological invasions focus on patterns and processes that are related to introduction, establishment, spread and impacts of introduced species. This review focuses on the ecological interactions operating during invasions by the most prominent group of insect vectors of disease, mosquitoes. First, we review characteristics of non-native mosquito species that have established viable populations, and those invasive species that have spread widely and had major impacts, testing whether biotic characteristics are associated with the transition from established non-native to invasive. Second, we review the roles of interspecific competition, apparent competition, predation, intraguild predation and climatic limitation as causes of impacts on residents or as barriers to invasion. We concentrate on the best-studied invasive mosquito, Aedes albopictus, evaluating the application of basic ecological theory to invasions by Aedes albopictus. We develop a model based on observations of Aedes albopictus for effects of resource competition and predation as barriers to invasion, evaluating which community and ecosystem characteristics favour invasion. Third, we evaluate the ways in which invasive mosquitoes have contributed to outbreaks of human and animal disease, considering specifically whether invasive mosquitoes create novel health threats, or modify disease transmission for existing pathogen-host systems.
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Affiliation(s)
- Steven A. Juliano
- Department of Biological Sciences, Behavior, Ecology, Evolution and Systematics Section, Illinois State University, Normal, IL 61790-4120, USA
| | - L. Philip Lounibos
- Florida Medical Entomology Laboratory, University of Florida, 200 9th St, SE, Vero Beach, FL 32962, USA
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23
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Juliano SA, Philip Lounibos L. Ecology of invasive mosquitoes: effects on resident species and on human health. Ecol Lett 2005. [DOI: 10.1111/j.1461-0248.2005.00755.x] [Citation(s) in RCA: 374] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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24
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Girard YA, Klingler KA, Higgs S. West Nile Virus Dissemination and Tissue Tropisms in Orally InfectedCulex pipiens quinquefasciatus. Vector Borne Zoonotic Dis 2004; 4:109-22. [PMID: 15228811 DOI: 10.1089/1530366041210729] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We investigated the spatial and temporal distribution of West Nile virus (WNV) in organs and tissues of Culex pipiens quinquefasciatus mosquitoes for up to 27 days following oral infection. WNV antigen was detected in paraffin-embedded mosquitoes by immunohistochemistry. Immunofluorescence assays were performed on dissected salivary glands and midguts and analyzed by confocal microscopy. We evaluated the route of virus dissemination following midgut escape and the relative importance of amplifying tissues in mosquito susceptibility to infection. WNV infection was persistent in all tissues analyzed including the midgut, salivary glands, nervous system, and fat body and only declined in the cytoplasm of posterior midgut epithelial cells over time. The phenomenon of cell-to-cell spread was observed in the midgut epithelium and WNV intensely infected both circular and longitudinal muscles of the same organ. It is possible that muscle tissue serves as a conduit for virus dissemination and contributes to WNV amplification, particularly late in infection. These findings provide insight into WNV infection dynamics in a highly susceptible, epidemiologically important, North American vector. Our results pave the way for future studies to analyze physical and biological barriers to WNV dissemination in less competent mosquitoes.
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Affiliation(s)
- Yvette A Girard
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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25
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Affiliation(s)
- Laura D Kramer
- Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159, USA
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26
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Abstract
Flaviviruses cause pleomorphic disease with significant morbidity and mortality worldwide. Interestingly, in contrast to most viruses, which subvert or avoid host immune systems, members of the neurotropic Japanese encephalitis serocomplex cause functional changes associated with increased efficacy of the immune response. These viruses induce increased cell surface expression of immune recognition molecules, including class I and II major histocompatibility complex (MHC) and various adhesion molecules. Increases are functional: infected cells are significantly more susceptible to both virus- and MHC-specific cytotoxic T cell lysis. Induced changes are modulated positively or negatively by Th1 and Th2 cytokines, as well as by cell cycle position and adherence status at infection. Infection also increases costimulatory molecule expression on Langerhans cells in the skin. Local interleukin-1 beta production causes accelerated migration of phenotypically altered Langerhans cells to local draining lymph nodes, where initiation of antiviral immune responses occur. The exact mechanism(s) of upregulation is unclear, but changes are associated with NF-kappa B activation and increased MHC and ICAM-1 gene transcription, independently of interferon (IFN) or other proinflammatory cytokines. Increased MHC and adhesion molecule expression may contribute to the pathogenesis of flavivirus encephalitis. Results from a murine model of flavivirus encephalitis developed in this laboratory suggest that fatal disease is immunopathological in nature, with IFN-gamma playing a crucial role. We hypothesize that these viruses may decoy the adaptive immune system into generating low-affinity T cells, which clear virus poorly, as part of their survival strategy. This may enable viral growth and immune escape in cycling cells, which do not significantly upregulate cell surface molecules.
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Affiliation(s)
- Nicholas J King
- Department of Pathology, Institute of Biomedical Research, School of Medical Sciences, University of Sydney 2006, New South Wales, Australia
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27
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Wong SJ, Demarest VL, Boyle RH, Wang T, Ledizet M, Kar K, Kramer LD, Fikrig E, Koski RA. Detection of human anti-flavivirus antibodies with a west nile virus recombinant antigen microsphere immunoassay. J Clin Microbiol 2004; 42:65-72. [PMID: 14715733 PMCID: PMC321652 DOI: 10.1128/jcm.42.1.65-72.2004] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2003] [Revised: 06/21/2003] [Accepted: 10/04/2003] [Indexed: 11/20/2022] Open
Abstract
We report a new, suspended-microsphere diagnostic test to detect antibodies to West Nile (WN) virus in human serum and cerebrospinal fluid (CSF). The microsphere immunofluorescence assay can be performed in less than 3 h on specimens of
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Affiliation(s)
- Susan J Wong
- Wadsworth Center, New York State Department of Health, Albany, New York 12201-2002, USA.
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28
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Nahimana A, Rabodonirina M, Helweg-Larsen J, Meneau I, Francioli P, Bille J, Hauser PM. Sulfa resistance and dihydropteroate synthase mutants in recurrent Pneumocystis carinii pneumonia. Emerg Infect Dis 2003; 9:864-7. [PMID: 12890330 PMCID: PMC3023424 DOI: 10.3201/eid0907.030249] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Failure of sulfa or sulfone prophylaxis is associated with mutations in Pneumocystis carinii gene coding for dihydropteroate synthase (DHPS). The DHPS genotype was analyzed in AIDS patients who had two separate episodes of P. carinii pneumonia. The results suggest that DHPS mutations can be selected de novo within patients by the pressure of a sulfa or sulfone drug.
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Affiliation(s)
| | | | | | - Isabelle Meneau
- Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | | | - Jacques Bille
- Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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29
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Ngo KA, Kramer LD. Identification of mosquito bloodmeals using polymerase chain reaction (PCR) with order-specific primers. JOURNAL OF MEDICAL ENTOMOLOGY 2003; 40:215-222. [PMID: 12693851 DOI: 10.1603/0022-2585-40.2.215] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A polymerase chain reaction (PCR) protocol was developed to identify host bloodmeals from mosquitoes. Primers for the cytochrome b gene were designed to distinguish between mammalian and avian bloodmeals and further differentiate among four avian orders: passeriformes, falconiformes, columbiformes, and galliformes. The assay was validated by testing tissues from 18 species of passeriformes, three species of falconiformes, three species of columbiformes, and two species of galliformes. American crows were distinguished from other passeriformes by restriction enzyme digestion. Host bloodmeals from engorged mosquitoes collected in New York State were identified to avian order level. PCR was able to detect the mosquito bloodmeal for up to 3 d after feeding on a quail. Significantly, these studies use order-specific primers in a single PCR test to identify mosquito bloodmeals.
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Affiliation(s)
- Kiet A Ngo
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, 5668 State Farm Road, Slingerlands, NY 12139, USA
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30
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Affiliation(s)
- C V Prowse
- Scottish National Blood Transfusion Service, Edinburgh, UK.
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31
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Abstract
West Nile virus (WNV) first appeared in the naive environment of the Western Hemisphere in 1999 in New York. Genetic analysis determined that the virus was introduced into the United States from the Mediterranean Basin. This review discusses the spread of the virus in 2001 from the initial focus in Queens, New York, to widespread activity in the eastern and midwestern United States. It concentrates on viral ecology, epizootiology, pathology, prediction, and prevention. Research questions to further our understanding of the transmission cycle of WNV are discussed, including host-preference studies, molecular confirmation of implicated mosquito vectors, and survival of WNV in the temperate environment of the United States. Comparisons are drawn with two other arboviruses enzootic in the United States, eastern equine encephalitis, and St. Louis encephalitis viruses. Although not recently introduced, these two viruses also demonstrated increased activity in the United States in 2001.
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Affiliation(s)
- K A Bernard
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Albany 12159, USA
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