Prevalence of West Nile Virus in Migratory Birds during Spring and Fall Migration

Dusek, Robert J.; McLean, Robert G.; Kramer, Laura D.; Ubico, Sonya R.; Dupuis, Alan P.; Ebel, Gregory D.; Guptill, Stephen C.

doi:10.4269/ajtmh.2009.09-0106

Cited by 61 publications

(38 citation statements)

References 33 publications

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“…A primary role of migratory birds in WNV introduction, reintroduction, and spread across Europe [135][136][137][138][139] and the Americas [140,141] is well documented. However, comparison of the levels of neutralizing antibodies in migratory and resident birds in the south of Spain [135,136] , the seroconversion observed in some recaptured resident birds of the same area [137] , and the significant number of positive resident birds found in Great Britain [142] and Italy [143] support that there is also local circulation of the virus.…”

Section: Ecologymentioning

confidence: 99%

West Nile virus: A re-emerging pathogen revisited

Martín-Acebes

Saiz²

2012

WJV

117

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Section: Ecologymentioning

confidence: 99%

West Nile virus: A re-emerging pathogen revisited

Martín-Acebes

Saiz²

2012

WJV

117

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“…[1][2][3][4] Proof of principal for long distance movement was shown recently in the Old World by the recovery of WNV from migrating storks 5 and WNV antibody from other migrant species. 6,7 Historically in the United States, large studies along the Mississippi and Atlantic flyways failed to document the introduction of encephalitis viruses by northbound migrants.…”

Section: Introductionmentioning

confidence: 99%

Migratory Birds and the Dispersal of Arboviruses in California

Reisen

Wheeler

Garcia

et al. 2010

The American Society of Tropical Medicine and Hygiene

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MATERIALS AND METHODS Bird collections.Migratory and resident birds were captured while transiting sites on the northeastern (35.51, −115.92) and northwestern (33.46, −116.06) shores of the Salton Sea, Coachella Valley, Riverside County, CA, from 1996 through 2005. In addition, migratory transients were targeted during collections made during the springs of 2006 and 2007. Migrants and other birds also were collected during 1996 through 2008 in Kern County, primarily from wetlands at the Kern National Wildlife Refuge (35.73,) and the Kern River (35.32,. The ecology of these areas, descriptions of arbovirus activity, and bird sampling methods have been described previously. 20,23 Briefly, birds were collected using multiple mist nets and grain-baited traps. Mist nets were 10 m long × 2.5 m tall and had 28-, 32-, or 60-mm mesh depending on the target species. Captured birds were banded with U.S. Geological Survey (USGS) bands, aged, sexed, and a 0.1 mL sample of blood collected from the jugular vein with 28-g needles. For antibody detection, blood samples were expelled into 0.9 mL of 0.9% saline solution, clarified through centrifugation, and stored at −70°C. During 2004During , 2006During , and 2007 blood samples from migratory species collected in Coachella Valley were expelled into 0.4 mL of virus diluent (phosphate buffered saline, 15% fetal bovine sera, antibiotics) and tested for infectious virus and antibody. Data from the California WNV Dead Bird Surveillance Program 24 on neotropical migrants that were found dead by the public, sent for necropsy, and tested positive for WNV RNA were included for comparison.Experimental infection. Abstract. Each spring large numbers of neotropical migrants traversing the Pacific flyway pass through the Coachella Valley enroute to northern destinations, providing an opportunity to test the hypothesis that mosquito-borne encephalitis viruses are introduced annually into California by migratory birds. A total of 5,632 sera were collected from 43 species of migrants during spring (April-June), of which 34 (0.61%) comprised of 14 species tested positive by enzyme immunoassay; only 10 were confirmed by plaque reduction neutralization tests (PRNT). In addition, of 1,109 migrants comprised of 76 species that were reported dead by the public and necropsied, 126 (11%) were positive for West Nile virus (WNV) RNA; however, only three (0.7%) of 428 birds tested during the spring were positive. Limited experimental infection studies with WNV showed that Orange-crowned Warblers were highly susceptible and frequently died, whereas most Yellow Warblers survived. Our results indicated that birds entering California rarely exhibited a history of infection and that most birds probably became infected after entering California.

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“…WNV perpetuates in nature in enzootic transmission cycles through alternating replication in (mainly avian) vertebrates and mosquitoes. The specific mosquito and avian hosts that are most important in a particular locality differ but tend to include Culex species mosquitoes and passerine birds (2,10). WNV infection of mammals, including humans and horses, occurs via spillover from this enzootic cycle.…”

mentioning

confidence: 99%

Nonconsensus West Nile Virus Genomes Arising during Mosquito Infection Suppress Pathogenesis and Modulate Virus Fitness In Vivo

Ebel

Fitzpatrick

Lim

et al. 2011

J Virol

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West Nile virus (WNV) is similar to other RNA viruses in that it forms genetically complex populations within hosts. The virus is maintained in nature in mosquitoes and birds, with each host type exerting distinct influences on virus populations. We previously observed that prolonged replication in mosquitoes led to increases in WNV genetic diversity and diminished pathogenesis in mice without remarkable changes to the consensus genome sequence. We therefore sought to evaluate the relationships between individual and group phenotypes in WNV and to discover novel viral determinants of pathogenesis in mice and fitness in mosquitoes and birds. Individual plaque size variants were isolated from a genetically complex population, and mutations conferring a small-plaque and mouse-attenuated phenotype were localized to the RNA helicase domain of the NS3 protein by reverse genetics. The mutation, an Asp deletion, did not alter type I interferon production in the host but rendered mutant viruses more susceptible to interferon compared to wild type (WT) WNV. Finally, we used an in vivo fitness assay in Culex quinquefasciatus mosquitoes and chickens to determine whether the mutation in NS3 influenced fitness. The fitness of the NS3 mutant was dramatically lower in chickens and moderately lower in mosquitoes, indicating that RNA helicase is a major fitness determinant of WNV and that the effect on fitness is host specific. Overall, this work highlights the complex relationships that exist between individual and group phenotypes in RNA viruses and identifies RNA helicase as an attenuation and fitness determinant in WNV.West Nile virus (WNV; Flaviviridae: Flavivirus) is a positivesense, single-stranded RNA (ssRNA) virus belonging to the Japanese encephalitis virus (JEV) serological complex of the flaviviruses. WNV perpetuates in nature in enzootic transmission cycles through alternating replication in (mainly avian) vertebrates and mosquitoes. The specific mosquito and avian hosts that are most important in a particular locality differ but tend to include Culex species mosquitoes and passerine birds (2, 10). WNV infection of mammals, including humans and horses, occurs via spillover from this enzootic cycle. Since its introduction into North America in 1999 (20), molecular epidemiologic studies have clearly demonstrated that the virus has evolved to maximize its transmission potential within local transmission cycles (8,11,23). This finding stimulated subsequent efforts to understand the details of the underlying evolutionary mechanisms that lead to population-level genetic and phenotypic changes in the virus. In brief, these studies demonstrated that WNV populations are genetically diverse within hosts (15), that genetic diversity may be shared between hosts (15), and that mosquito infection drives genetic diversification of the virus population both through relaxation of purifying selection and through selection of rare genotypes resulting from RNA interference (RNAi) (4,16,17). Thus, in the WNV transmission cycle, different...

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Prevalence of West Nile Virus in Migratory Birds during Spring and Fall Migration

Cited by 61 publications

References 33 publications

West Nile virus: A re-emerging pathogen revisited

West Nile virus: A re-emerging pathogen revisited

Migratory Birds and the Dispersal of Arboviruses in California

Nonconsensus West Nile Virus Genomes Arising during Mosquito Infection Suppress Pathogenesis and Modulate Virus Fitness In Vivo

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