RESUMO
Two recent cases of human infection with Tonate virus, one of which was a fatal case of encephalitis, have renewed interest in these viruses in French Guiana. The clinical aspects of confirmed and probable cases of infection with this virus indicate that it has pathogenic properties in humans similar to those of other viruses of the Venezuelan equine encephalitis complex. To determine the prevalence of antibodies to Tonate virus in the various ethnic groups and areas of French Guiana, 3,516 human sera were tested with a hemagglutination inhibition test. Of these, 11.9% were positive for the virus, but significant differences in seroprevalence were found by age, with an increase with age. After adjustment for age, significant differences were found between places of residence. The prevalence of antibody to Tonate virus was higher in savannah areas, especially in the Bas Maroni (odds ratio [OR] = 22.2, 95% confidence interval [CI] = 15.2-32.4) and Bas Oyapock areas (OR = 13.4; 95% CI = 9.8-18.4). The ethnic differences observed in this study were due mainly to differences in place of residence, except that whites were significantly less frequently infected than other ethnic groups. This study indicates that Tonate virus infection is highly prevalent in French Guiana, especially in savannah areas.
Assuntos
Vírus da Encefalite Equina Venezuelana/isolamento & purificação , Encefalomielite Equina/epidemiologia , Adulto , Sequência de Bases , Primers do DNA , Encefalomielite Equina/diagnóstico , Encefalomielite Equina/patologia , Encefalomielite Equina/transmissão , Feminino , Guiana Francesa/epidemiologia , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Estudos SoroepidemiológicosRESUMO
Four geographic variants (topotypes) of yellow fever (YF) virus from Africa and South America previously determined by RNA oligonucleotide mapping were analyzed for their structural, antigenic and virulence characteristics. The electrophoretic migration mobility and carbohydrate content of the envelope protein E characterized YF virus strains of South America. The NS 1 protein of South American and Central African YF virus strains was not precipitated by anti-NS 1 monoclonal antibodies (MAB) that precipitated NS 1 of West African strains. No distinction could be made among the YF virus strains on the basis of the neutralizing capacity of available MAB. South American, but not African YF virus strains were virulent for 8-day-old mice upon intraperitoneal inoculation. The results permitted characterization of topotypes of Central Africa and South America but failed to differentiate YF strains from West Africa.
Assuntos
Proteínas Virais/análise , Vírus da Febre Amarela/análise , África , Animais , Antígenos Virais/análise , Antígenos Virais/imunologia , Eletroforese em Gel de Poliacrilamida , Epitopos/imunologia , Camundongos , Peso Molecular , América do Sul , Proteínas do Envelope Viral/análise , Proteínas do Envelope Viral/imunologia , Proteínas não Estruturais Virais , Proteínas Virais/imunologia , Virulência , Vírus da Febre Amarela/imunologia , Vírus da Febre Amarela/patogenicidadeRESUMO
Isolates of yellow fever (YF) virus from Africa (Senegambia, Central African Republic, Ivory Coast, Burkina Faso) and from South America (Panama, Ecuador, Trinidad) were examined by oligonucleotide fingerprinting of the 40S genome RNA. Geographically isolated and epidemiologically unrelated viruses were very distinct. On the basis of the T1 oligonucleotide fingerprints of each isolate, four geographical variants (topotypes) of YF virus isolated within the same period of time have been established. The Ivory Coast and Burkina Faso topotypes were similar. In the Central African Republic, two variants could be found exhibiting 70 to 75% homology to one another. In South America, the three analysed strains exhibited only about 70% homology, but could be classified in the same topotype. The oligonucleotide fingerprints of the genome RNA offered a useful tool for the understanding of YF virus variability.
Assuntos
Genes Virais , Vírus da Febre Amarela/genética , Aedes , África , Animais , Demografia , Humanos , RNA Viral/genética , RNA Viral/isolamento & purificação , Homologia de Sequência do Ácido Nucleico , América do Sul , Especificidade da Espécie , Vírus da Febre Amarela/isolamento & purificaçãoRESUMO
This is the first case in man of Ilheus virus infection in french Guyana. We noted the mild febrile illness in this case. This strain of virus was shown to be closely related to Ilheus virus. The serological reactions are reported.
Assuntos
Arbovírus/isolamento & purificação , Animais , Arbovírus/imunologia , Testes de Fixação de Complemento , Feminino , Guiana Francesa , Testes de Inibição da Hemaglutinação , Humanos , CamundongosRESUMO
Isolation of arboviruses was attempted from October 1972 till the end of 1973 from mosquitoes caught in both a savannah forest near Powaka and a coastal area near "Fernandesweg" in Surinam. Two types of arbovirus were isolated: eleven strains of Tonate and ten strains of Guama-group. In the savannah area ten strains of Tonate and five of Guama-group were isolated, whereas in the coastal area the numbers were one and five, respectively. All strains in the savannah area were isolated from pools of Culex portesi. In the coastal area the strains were obtained as follows: one Tonate strain from a pool of Culex taeniopus, four Guama-group strains from pools of Coquillettidia venezuelensis, and one from a pool of Culex spp.
Assuntos
Arbovírus/isolamento & purificação , Culicidae/microbiologia , Aedes/microbiologia , Animais , Anopheles/microbiologia , Culex/microbiologia , Insetos Vetores , Orthobunyavirus/isolamento & purificação , SurinameRESUMO
Venezuelan encephalitis virus is a constant menace to man and to animals, particularly horses. Two as yet unreported strains have been isolated in French Guyana: Ca An 410d (Tonate) and Ca Ar 508 (Cabassou). They are not neurovirulent after peripheral inoculation into adult mice and guinea pigs. Cabassou is not pathogenic for adult mice after intracerebral inoculation. A third strain, Ca Ar 19007, is antigenically identical by complement-fixation with Cabassou, but appears to cross react with other strains, Tonate, when injected intra-peritoneally or sub-cutaneously, protects adult mice against intra-cerebral or intra-peritoneal challenge with Everglades virus. The Ca Ar 19007 isolate causes total protection against Everglades virus if injected intra-peritoneally, but only partial protection by the sub-cutaneous route. Cabassou, on the other hand, if injected intra-peritoneally will protect against intra-cerebral challenge with Everglades. Tonate and Ca Ar 19007 thus appear to be naturally occurring attenuated variants of the Venezuelan encephalitis virus complex, which can protect mice against intra-cerebral infection with neurovirulent strains.