RESUMO
Despite evidence of arbovirus activity in northwestern Uganda (West Nile Sub-region), there is very limited information on the mosquito fauna of this region. The only published study reported 52 mosquito species in northwestern Uganda but this study took place in 1950 and the information has not been updated for more than 60 yr. In January and June 2011, CO2 baited-light traps were used to collect 49,231 mosquitoes from four different locations, Paraa (9,487), Chobe (20,025), Sunguru (759), and Rhino Camp (18,960). Overall, 72 mosquito species representing 11 genera were collected. The largest number of distinct species was collected at Chobe (43 species), followed by Paraa (40), Sunguru (34), and Rhino Camp (25). Only eight of the 72 species (11.1%) were collected from all four sites: Aedes (Stegomyia) aegypti formosus (Walker), Anopheles (Cellia) funestus group, Culex (Culex) decens group, Cx. (Culex) neavei Theobald, Cx. (Culex) univittatus Theobald, Cx. (Culiciomyia) cinereus Theobald, Cx. (Oculeomyia) poicilipes (Theobald), and Mansonia (Mansonoides) uniformis (Theobald). Fifty-four species were detected in northwestern Uganda for the first time; however, these species have been detected elsewhere in Uganda and do not represent new introductions to the country. Thirty-three species collected during this study have previously been implicated in the transmission of arboviruses of public health importance.
Assuntos
Distribuição Animal , Culicidae/fisiologia , Animais , Culicidae/classificação , UgandaRESUMO
RAPD-PCR polymorphisms at 57 presumptive loci were used to examine the breeding structure of the mosquito Aedes aegypti in Puerto Rico. Mosquitoes were sampled from 16 locations in six cities and samples were located in a nested spatial design to examine local patterns of gene flow. Allele frequencies were estimated assuming (1) that genomic regions amplified by RAPD-PCR segregate as dominant alleles, (2) that genotypes at RAPD loci are in Hardy-Weinberg proportions, (3) identity in state (iis) among dominant amplified alleles and (4) iis among null alleles. The average genic heterozygosity was 0.354, more than twice the level detected in earlier allozyme surveys. Nested analysis of variance indicated extensive genetic differentiation among locations within cities. Effective migration rates (Nm) among cities were estimated from FST assuming an island model of migration. Estimates of Nm ranged from 9.7 to 12.2 indicating a high dispersal rate. The large number of polymorphisms revealed by RAPD-PCR allowed the distribution of FST and linkage disequilibrium to be examined among loci and demonstrated that small samples inflate FST and linkage disequilibrium. No linkage disequilibrium maintained through epistasis was detected among alleles at the 57 loci.
Assuntos
Aedes/genética , Técnica de Amplificação ao Acaso de DNA Polimórfico , Animais , Cruzamento , Mapeamento Cromossômico , Genes Dominantes , Genes de Insetos , Marcadores Genéticos , Desequilíbrio de Ligação , Modelos Estatísticos , Polimorfismo Genético , Porto RicoRESUMO
We report the application of a molecular genetic technique to estimate the number of full-sibling families of Aedes aegypti contained in oviposition traps. Randomly amplified polymorphic DNA amplified by the polymerase chain reaction markers were used to estimate the numbers and sizes of families in traps at field locations in San Juan, Puerto Rico. Forty-nine presumptive loci were amplified with five primers in a total of 813 individuals from 26 sites. The average family size was 10.95, but the size distribution was skewed with an excess of small families containing 1-2 individuals. The number of families increased with the number of eggs in traps; however, the average family size decreased as the number of eggs increased. This suggests that females oviposited only a few eggs in traps that were recently placed in the field and lacked mosquito eggs or fewer eggs were oviposited as traps became crowded.
Assuntos
Aedes/fisiologia , DNA/análise , Insetos Vetores/fisiologia , Oviposição , Aedes/genética , Alelos , Animais , Análise por Conglomerados , DNA/genética , Feminino , Frequência do Gene , Insetos Vetores/genética , Reação em Cadeia da Polimerase , Polimorfismo Genético , Porto Rico , Análise de RegressãoRESUMO
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
We have partially cloned and sequenced the genome of a Peruvian yellow fever virus isolate (1899/81) and compared the nucleotide and deduced amino acid sequences of this strain with the previously published sequence of the West African yellow fever virus strain Asibi. In the 3594 base region sequenced, which contains the structural genes (C, M, E), all but the 72 3'-terminal nucleotides of the NS1 gene and 108 nucleotides of the 5' non-coding region, 515 nucleotide substitutions were detected. Nucleotide divergence was lowest in the 5' non-coding region, 2.8%, compared with an average rate of 14.7% in the coding regions. Over 91% of the 512 nucleotide changes in the coding region were silent; 44 amino acid substitutions resulted. The capsid protein was the least conserved, whereas the M protein was the most highly conserved (6.7% and 1.3% divergence, respectively). The envelope protein had 18 amino acid changes (3.7% divergence), one of which created an additional site for potential glycosylation of the 1899/81 virus. NS1 protein divergence (3.9%) was similar to that seen in the E protein. Of the 44 amino acid substitutions found, 34 (77%) were conservative. The highest number of nonconservative differences occurred in the envelope glycoprotein. These changes may significantly affect the antigenic and biological functions of the viruses.
Assuntos
Capsídeo/genética , Proteínas do Core Viral/genética , Proteínas Estruturais Virais/genética , Vírus da Febre Amarela/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Clonagem Molecular/métodos , Humanos , Dados de Sequência Molecular , Sondas de Oligonucleotídeos , Peru , RNA Viral/genética , Radioimunoensaio , Homologia de Sequência do Ácido Nucleico , Proteínas não Estruturais Virais , Vírus da Febre Amarela/isolamento & purificaçãoRESUMO
The effect of a 3-hour versus a 10-hour preoperative fasting interval on the gastric residual volume and gastric pH of pediatric patients was evaluated. Forty-four healthy infants, 1 month to 5 years of age, were randomly assigned to one of two groups. The 3-hour nil per os (NPO) group consisted of 19 infants kept NPO for 3 hours following ingestion of up to 4 ounces of 5% dextrose in water (D5W). The control group consisted of 25 infants who remained NPO an average of 10 hours prior to surgery. Gastric residual volume was calculated using the dye-dilution technique. After the dye marker was injected into the stomach, complete aspiration of the stomach (including the volume of dye marker plus residual gastric contents) was attempted as another method to measure gastric residual volume. There were no significant differences in gastric residual volume between the 3-hour and the 10-hour NPO groups using either the dye-dilution or aspiration methods. However, there were significant differences between the two measuring techniques. Gastric residual volume was significantly greater in volume when measured by the dye-dilution technique than it was when measured by the aspiration technique in both the 10-hour (p less than 0.009) and the 3-hour (p less than 0.0009) NPO groups. Complete aspiration of a known volume of fluid injected through the orogastric tube was not possible in 23 of the 44 (52.4%) infants. Mean gastric pH was less than 2.0 in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Jejum , Ácido Gástrico/fisiologia , Conteúdo Gastrointestinal , Peso Corporal , Pré-Escolar , Técnica de Diluição de Corante , Glucose/administração & dosagem , Humanos , Concentração de Íons de Hidrogênio , Lactente , Estudos Prospectivos , Distribuição Aleatória , Método Simples-Cego , Sucção , Fatores de TempoRESUMO
Three strains of Aedes albopictus from Brazil were examined for their ability to vertically transmit dengue 1 (DEN-1) and dengue 4 (DEN-4) viruses. Parental females were uniformly infected by parenteral inoculation of virus, and 8,121 F1 progeny from DEN-1 and DEN-4 infected mothers were pooled in lots of approximately 50 and tested for virus. Seven of 60 pools were positive for DEN-1 virus, and 1 of 121 pools was positive for DEN-4 virus. In DEN-1 assays, the minimum infection rate (MIR) for larvae (2 pools tested) was 1:84. Among positive cohorts of adults, pooled by sex and by geographic strain of mosquito, the MIR ranged from 1:193 to 1:626 for males and from 1:187 to 1:311 for females. Only a single pool of adult females was positive for DEN-4 virus (MIR 1:1022 for an adult female cohort from Santa Teresa). These results indicate that Brazilian Ae. albopictus have the potential to play a role in the maintenance of dengue viruses in nature.
Assuntos
Aedes/microbiologia , Vírus da Dengue/isolamento & purificação , Insetos Vetores , Animais , Antígenos Virais/análise , Brasil , Vírus da Dengue/imunologia , Feminino , Larva/microbiologia , Masculino , Especificidade da EspécieRESUMO
Arbovirus epidemics in a geographic region are believed to depend on the presence of susceptible or "competent" arthropod vectors. We demonstrate that an urban, Aedes aegypti-borne, epidemic of yellow fever occurred in 1987 although the mosquito vector was relatively resistant to infection and transmitted the virus inefficiently. Twenty-six percent of the experimental mosquitoes from the epidemic area that ingested yellow fever virus became infected and only 7% of these transmitted the virus. In contrast, 80% of an exotic susceptible strain of Ae. aegypti became infected and 43% were able to transmit. We also show that no other potential vectors were active during the epidemic and that the local Ae. aegypti were present in extremely large numbers. These results document, for the first time, that, in the presence of high population density an incompetent mosquito vector can initiate and maintain virus transmission resulting in an epidemic.
Assuntos
Aedes/microbiologia , Febre Amarela/epidemiologia , Adulto , Animais , Pré-Escolar , Surtos de Doenças , Vetores de Doenças , Feminino , Frequência do Gene , Inquéritos Epidemiológicos , Humanos , Lactente , Isoenzimas/genética , Nigéria/epidemiologia , Porto Rico/epidemiologia , População Urbana , Viremia/complicações , Viremia/epidemiologia , Viremia/genética , Febre Amarela/complicações , Febre Amarela/genética , Febre Amarela/transmissão , Vírus da Febre Amarela/genéticaRESUMO
A combination of virus infection and transmission experiments showed that a Houston, Texas strain of Aedes albopictus is a competent vector for dengue (DEN), yellow fever (YF) and Ross River (RR) viruses. However, at 14 days incubation, DEN virus infection rates in a Puerto Rican strain of Aedes aegypti were significantly higher for each of the four DEN serotypes, except DEN-1, than in Houston Ae. albopictus fed simultaneously on the same virus suspensions. The degree of correlation between disseminated DEN infection rates in Houston Ae. albopictus and transmission to an in vitro system ranged from 42 to 88% for the four DEN serotypes. No significant difference was noted in YF virus infection rates or transmission rates in the two mosquito species fed on the same virus suspensions and incubated for the same time period. Also, RR virus infection and transmission rates in Houston and Hawaiian strains of Ae. albopictus were generally comparable.
Assuntos
Aedes/microbiologia , Alphavirus/isolamento & purificação , Vírus da Dengue/isolamento & purificação , Insetos Vetores , Ross River virus/isolamento & purificação , Vírus da Febre Amarela/isolamento & purificação , Aedes/imunologia , Animais , Antígenos Virais/análise , Vírus da Dengue/classificação , Feminino , Camundongos , Sorotipagem , Texas , Infecções por Togaviridae/transmissão , Febre Amarela/transmissãoAssuntos
Culicidae/microbiologia , Insetos Vetores/microbiologia , Meningoencefalite/transmissão , Animais , Arbovírus/isolamento & purificação , Galinhas , Vírus da Encefalite/isolamento & purificação , Feminino , Mordeduras e Picadas de Insetos , Meningoencefalite/microbiologia , Ensaio de Placa ViralRESUMO
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.
Assuntos
Aedes/microbiologia , Insetos Vetores/microbiologia , Vírus da Febre Amarela/crescimento & desenvolvimento , Aedes/enzimologia , Aedes/genética , África , Animais , Ásia , América Central , Feminino , Variação Genética , Isoenzimas/análise , Boca/microbiologia , América do Sul , Estados Unidos , Índias OcidentaisRESUMO
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.(AU)