RESUMO
In the last 5 years, there has been only one reported human case of West Nile virus (WNV) disease in northern Mexico. To determine if the virus was still circulating in this region, equine and entomological surveillance for WNV was conducted in the state of Nuevo Leon in northern Mexico in 2006 and 2007. A total of 203 horses were serologically assayed for antibodies to WNV using an epitope-blocking enzyme-linked immunosorbent assay (bELISA). Seroprevalences for WNV in horses sampled in 2006 and 2007 were 26% and 45%, respectively. Mosquito collections in 2007 produced 7365 specimens representing 15 species. Culex mosquitoes were screened for WNV RNA and other genera (Mansonia, Anopheles, Aedes, Psorophora and Uranotaenia) were screened for flaviviruses using reverse-transcription (RT)-PCR. Two pools consisting of Culex spp. mosquitoes contained WNV RNA. Molecular species identification revealed that neither pool included Culex quinquefasciatus (Say) (Diptera:Culicidae) complex mosquitoes. No evidence of flaviviruses was found in the other mosquito genera examined. These data provide evidence that WNV is currently circulating in northern Mexico and that non-Cx. quinquefasciatus spp. mosquitoes may be participating in the WNV transmission cycle in this region.
Assuntos
Culicidae/virologia , Doenças dos Cavalos/virologia , Cavalos/virologia , Insetos Vetores/virologia , Febre do Nilo Ocidental/veterinária , Vírus do Nilo Ocidental/isolamento & purificação , Animais , Anticorpos Antivirais/sangue , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Doenças dos Cavalos/sangue , Doenças dos Cavalos/epidemiologia , Masculino , México/epidemiologia , Dados de Sequência Molecular , Prevalência , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Análise de Sequência de RNA/veterinária , Homologia de Sequência , Estudos Soroepidemiológicos , Especificidade da Espécie , Febre do Nilo Ocidental/sangue , Febre do Nilo Ocidental/epidemiologia , Febre do Nilo Ocidental/virologiaRESUMO
Vesicular stomatitis (VS) outbreaks occurred in the southwestern United States of America in 1995, 1997 and 1998. The epidemiology of VS is not understood completely and some of the epidemiologic aspects of this disease are currently under investigation. In this study, daily maximum temperature, daily minimum temperature, daily mean temperature, daily mean relative humidity and daily total precipitation were collected at the Sevilleta Long Term Ecological Research site in central New Mexico. Discriminant analysis was used to identify the climatic variables best able to classify in which months VS would occur. The study found that the amounts of precipitation occurring two, ten, eleven and twelve months prior to the month in which cases were diagnosed, were the climatic variables that best described the occurrence of VS cases. The association of VS cases and precipitation suggests that, like numerous other arthropod-borne diseases, transmission of the disease-causing pathogen is linked to variations in climate.
Assuntos
Clima , Infecções por Rhabdoviridae/veterinária , Estomatite/veterinária , Vírus da Estomatite Vesicular Indiana , Animais , Animais Domésticos , Análise Discriminante , Umidade , Análise Multivariada , New Mexico/epidemiologia , Chuva , Infecções por Rhabdoviridae/epidemiologia , Estações do Ano , Estomatite/epidemiologia , TemperaturaRESUMO
A population genetic analysis of gene flow was conducted among 10 Aedes aegypti collections from seven cities along the northeastern coast of Mexico. Four collections were made from Monterrey to examine local patterns of gene flow. Markers included 60 random amplified polymorphic DNA (RAPD) loci amplified by the polymerase chain reaction and single strand conformation polymorphism analysis of variation in a 387-basepair region of the NADH dehydrogenase subunit 4 from the mitochondrial DNA (mtDNA). Seven mitochondrial haplotypes were detected and phylogenetic analysis identified two well-supported clades. Regression analysis of geographic distances and pairwise FST estimated from RAPD markers indicated that populations are isolated by distance and that free gene flow occurs among collections within 90-250 km. Isolation by distance was not detected using mtDNA haplotypes. The Nuevo Laredo collection had unique RAPD and mtDNA haplotype frequencies and reduced heterozygosity suggesting that few mosquitoes established this population.
Assuntos
Aedes/genética , Dengue/transmissão , Frequência do Gene/genética , Variação Genética/genética , Insetos Vetores/genética , Febre Amarela/transmissão , Aedes/química , Animais , Primers do DNA/química , DNA Mitocondrial/química , DNA Mitocondrial/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Feminino , Haplótipos , Humanos , Insetos Vetores/química , México , Filogenia , Reação em Cadeia da Polimerase , Polimorfismo Conformacional de Fita Simples , Técnica de Amplificação ao Acaso de DNA Polimórfico , Análise de Regressão , Análise de Sequência de DNARESUMO
The co-circulation of all 4 dengue virus serotypes in the same community, common since the 1950s in Southeast Asia, has now become a frequent occurrence in many Caribbean Islands, Mexico, and Central and South America in the past 20 years. As a consequence, the frequency of concurrent infections would be expected to increase in these areas. To assess this, using state of the art technology, we screened viremic serum samples and mosquitoes inoculated with serum samples collected during epidemics involving multiple dengue virus serotypes in Indonesia, Mexico, and Puerto Rico for virus isolation. Of 292 samples tested, 16 (5.5%) were found to contain 2 or more dengue viruses by an indirect immunofluorescence test and/or the reverse transcriptase-polymerase chain reaction.
Assuntos
Vírus da Dengue/classificação , Surtos de Doenças , Dengue Grave/virologia , Animais , Anticorpos Monoclonais , Anticorpos Antivirais/sangue , Bioensaio , Células Cultivadas , Culicidae/virologia , Primers do DNA/química , Vírus da Dengue/genética , Vírus da Dengue/imunologia , Vírus da Dengue/patogenicidade , Eletroforese em Gel de Ágar , Técnica Direta de Fluorescência para Anticorpo , Humanos , Indonésia/epidemiologia , México/epidemiologia , Porto Rico/epidemiologia , RNA Viral/química , RNA Viral/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sorotipagem , Dengue Grave/sangue , Dengue Grave/epidemiologiaRESUMO
To identify T-helper (Th)-cell epitopes, we analyzed 25 synthetic peptides, which included most of the 495-amino-acid sequence of the envelope (E)-glycoprotein of dengue 2 virus. The peptides were analyzed in three mouse strains, BALB/c (H-2d), C57BL/6 (H-2b), and outbred NIH-Swiss, for their ability to elicit antibody or prime the Th-cell compartment following two inoculations in Freund's incomplete adjuvant. Sixteen peptides were able to elicit an antipeptide antibody response in one or more mouse strain. Eleven antipeptide serum pools were able to bind to virus in ELISA. Fifteen peptides primed one or more haplotype for an in vitro antipeptide Th-cell response as measured by blastogenesis. Th-cell activation was generally confirmed by measurable in vitro production of interleukin (IL)-2/IL-4. Nine peptides that were positive for in vitro blastogenesis, 1-2, 35, 4-6, 79, 142, 208, 06, 16, and 17, elicited virus-reactive Th-cells in vitro in H-2d mice. Two of these peptides (4-6 and 17) were able to prime virus-reactive Th-cells in H-2b mice. Nine peptides primed outbred mice in vitro for an antiviral antibody response significantly greater than that seen in animals primed with an irrelevant peptide. These results correlate with, and expand on, our previous observations based on a smaller set of synthetic peptides derived from the E-glycoprotein of Murray Valley encephalitis virus and suggest that synthetic peptides can function as E-glycoprotein Th-cell epitopes. The similarity of results between two distantly related flaviviruses suggests that E-glycoprotein Th-cell epitopes are consistent in location and activity.
Assuntos
Antígenos Virais/imunologia , Vírus da Dengue/imunologia , Epitopos/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Proteínas do Envelope Viral/imunologia , Animais , Anticorpos Antivirais/biossíntese , Anticorpos Antivirais/sangue , Antígenos Virais/sangue , Glicoproteínas/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Fragmentos de Peptídeos/imunologia , Proteínas do Envelope Viral/sangueRESUMO
Four monoclonal antibody-resistant variants (MARVs) of Venezuelan equine encephalitis (VEE) virus were used to study mosquito-virus interactions. In vitro experiments using an Aedes albopictus cell line, C6/36, demonstrated that an amino acid change in the glycoprotein E2h epitope (MARV 1A3B-7) decreased virus growth when compared with the wild-type, Trinidad donkey virus, and its vaccine derivative, TC-83. The MARVs replicated as efficiently as the parent virus when inoculated into Aedes aegypti mosquitoes, but MARV 1A3B-7 was restricted in its ability to infect and disseminate from the midgut following oral infection. These results demonstrate that a single amino acid change in the E2 glycoprotein can affect the ability of VEE virus to replicate and disseminate in Ae. aegypti mosquitoes.
Assuntos
Vírus da Encefalite Equina Venezuelana/genética , Proteínas do Envelope Viral/genética , Replicação Viral , Aedes/microbiologia , Animais , Anticorpos Monoclonais/imunologia , Linhagem Celular , Cricetinae , Vírus da Encefalite Equina Venezuelana/química , Vírus da Encefalite Equina Venezuelana/fisiologia , Insetos Vetores/microbiologia , Cinética , Células Vero , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/imunologiaRESUMO
Twenty-eight populations representing a worldwide distribution of Aedes aegypti were tested for their ability to become orally infected with yellow fever virus (YFV). Populations had been analyzed for genetic variations at 11 isozyme loci and assigned to one of 8 genetic geographic groups of Ae. aegypti. Infection rates suggest that populations showing isozyme genetic relatedness also demonstrate similarity to oral infection rates with YFV. The findings support the hypothesis that genetic variation exists for oral susceptibility to YFV in Ae. aegypti.