RESUMO
Pirital-like virus isolates from rodents collected in a variety of habitats within a six-state area of central Venezuela were analyzed genetically by amplifying a portion of the nucleocapsid protein gene using RT-PCR. Comparisons of the sequences from 30 selected Pirital-like virus isolates demonstrated up to 26% divergence in nucleotide sequences and up to 16% divergence in deduced amino acid sequences. Within the Pirital monophyletic group, 14 distinct lineages or genotypes, differing by at least 6% in nucleotide sequences, were identified. Although sample sizes were small for some lineages, many of the different genotypes were sampled in only one region or locality, suggesting allopatric divergence. Complement fixation tests with representatives of the most divergent Pirital virus lineages failed to delineate multiple species or subtypes within the Pirital clade. These results indicate that the previously proposed 12% nucleocapsid protein amino acid sequence divergence cutoff value for delineating arenavirus species is not appropriate for the entire family. When individual clones were examined from PCR amplicons, a mean of 0.17% sequence diversity vs the consensus sequences was detected, suggesting diverse quasispecies populations within infected rodent hosts. Possible explanations for the extreme genetic diversity within and among Pirital virus populations in infected rodents are discussed.
Assuntos
Arenaviridae/genética , Roedores/virologia , Animais , Arenaviridae/classificação , Testes de Fixação de Complemento , Variação Genética , Dados de Sequência Molecular , Filogenia , Sorotipagem , VenezuelaRESUMO
Despite intensive surveillance, Venezuelan hemorrhagic fever (VHF), caused by Guanarito (GTO) virus, has been detected in only a small region of western Venezuela. To determine whether VHF is associated with a particular regional GTO virus strain(s), 29 isolates from rodents and humans throughout the surrounding regions were analyzed by partial sequencing of the nucleocapsid protein gene. Phylogenetic trees delineated nine distinct GTO genotypes that differ by 4-17% in nucleotides and up to 9% in amino acid sequences; most appeared to be restricted to discrete geographic regions, although a few genotypes were isolated in several locations. Each genotype included at least one strain recovered from a rodent, but only two genotypes were isolated from VHF cases. The presence outside of the endemic/epidemic region of two genotypes isolated also from VHF cases suggests that human pathogenic viruses occur outside of the endemic zone, but do not frequently infect people and/or cause apparent disease there. VHF does not appear to be associated with a GTO virus genotype that is restricted to a certain rodent species. When quasispecies diversity was examined, rodent isolates had higher sequence variation than human isolates. One rodent isolate included a mixture of two phylogenetically distinct genotypes, suggesting a dual infection.
Assuntos
Arenavirus do Novo Mundo/classificação , Arenavirus do Novo Mundo/genética , Genes Virais , Febre Hemorrágica Americana/virologia , Roedores/virologia , Animais , Arenavirus do Novo Mundo/imunologia , Arenavirus do Novo Mundo/isolamento & purificação , Doenças Endêmicas , Variação Genética , Genótipo , Febre Hemorrágica Americana/epidemiologia , Febre Hemorrágica Americana/veterinária , Humanos , Dados de Sequência Molecular , Nucleocapsídeo/genética , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Doenças dos Roedores/virologia , Análise de Sequência de DNA , Venezuela/epidemiologiaRESUMO
Chronic infections in specific rodents appear to be crucial to the long-term persistence of arenaviruses in nature. The cane mouse, Zygodontomys brevicauda, is a natural host of Guanarito virus (family Arenaviridae), the etiologic agent of Venezuelan hemorrhagic fever. The purpose of this study was to elucidate the natural history of Guanarito virus infection in Z. brevicauda. Thirty-nine laboratory-reared cane mice each were inoculated subcutaneously with 3.0 log10 plaque-forming units of the Guanarito virus prototype strain INH-95551. No lethality was associated with infection in any animal, regardless of age at inoculation. The 13 newborn, 14 weanling, and 8 of the 12 adult animals developed chronic viremic infections characterized by persistent shedding of infectious virus in oropharyngeal secretions and urine. These findings indicate that Guanarito virus infection in Z. brevicauda can be chronic and thus support the concept that this rodent species is the natural reservoir of Guanarito virus.
Assuntos
Arenaviridae/patogenicidade , Arenavirus do Novo Mundo/patogenicidade , Febre Hemorrágica Americana/fisiopatologia , Animais , Anticorpos Antivirais/sangue , Arenaviridae/isolamento & purificação , Arenavirus do Novo Mundo/isolamento & purificação , Febre Hemorrágica Americana/patologia , Febre Hemorrágica Americana/urina , Muridae , Orofaringe/virologia , Baço/virologia , VenezuelaRESUMO
The objective of this study was to elucidate the natural rodent host relationships of Guanarito and Pirital viruses (family Arenaviridae) in the plains of central Venezuela. Ninety-two arenavirus isolates from 607 animals, representing 10 different rodent species, were characterized to the level of serotype. The 92 isolates comprised 19 Guanarito virus strains and 73 Pirital virus strains. The 19 Guanarito virus isolates were from Zygodontomys brevicauda; 72 (98.6%) of the 73 Pirital virus isolates were from Sigmodon alstoni. These results indicate that the natural rodent associations of these 2 sympatric arenaviruses are highly specific and that Z brevicauda and S. alstoni are the principal rodent hosts of Guanarito and Pirital viruses, respectively.
Assuntos
Arenavirus/isolamento & purificação , Roedores/virologia , Animais , Arenavirus/classificação , Arenavirus/genética , Vetores de Doenças , Ensaio de Imunoadsorção Enzimática , Filogenia , VenezuelaRESUMO
This paper describes the isolation and partial genetic characterization of a hantavirus from a pygmy rice rat, Oligoryzomys microtis, collected within the urban area of Iquitos, Loreto Department, Peru. The virus, designated HTN-007, exhibited the highest degree of genetic similarity to Rio Mamore virus, which was originally described from the same rodent species in eastern Bolivia. Comparison of small and medium segment nucleotide sequence data from HTN-007 and Rio Mamore virus revealed 87% and 85% sequence identity, respectively. Based on these analyses, HTN-007 appears to be a variant of Rio Mamore virus. As such, it represents the first successful isolation of Rio Mamore virus and the first evidence for the existence of a hantavirus in Peru. Serologic studies done by immunofluorescence on blood samples of 56 O. microtis trapped at the collection site indicated that 21.4% had antibodies to hantavirus. In view of the proximity of this rodent species to humans and the close phylogenetic relationship of Rio Mamore virus to hantaviruses that have been associated with human disease, Rio Mamore virus may be a hantavirus of some public health importance in tropical South America.
Assuntos
Infecções por Hantavirus/transmissão , Muridae/imunologia , Orthohantavírus/isolamento & purificação , Animais , Anticorpos Antivirais/sangue , Sequência de Bases , Chlorocebus aethiops , Primers do DNA/química , DNA Viral/química , Técnica Indireta de Fluorescência para Anticorpo/veterinária , Orthohantavírus/genética , Orthohantavírus/imunologia , Infecções por Hantavirus/imunologia , Pulmão/patologia , Microscopia Eletrônica , Peru , Filogenia , Reação em Cadeia da Polimerase/veterinária , RNA Viral/isolamento & purificação , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico , População Urbana , Células VeroRESUMO
Epidemiological and clinical data are presented on 165 cases of Venezuelan hemorrhagic fever (VHF), a newly emerging viral zoonosis caused by Guanarito virus (of the family Arenaviridae). The disease is endemic in a relatively circumscribed area of central Venezuela. Since its first recognition in 1989, the incidence of VHF has peaked each year between November and January, during the period of major agricultural activity in the region of endemicity. The majority of cases have involved male agricultural workers. Principal symptoms among the patients with VHF included fever, malaise, headache, arthralgia, sore throat, vomiting, abdominal pain, diarrhea, convulsions, and a variety of hemorrhagic manifestations. The majority of patients also had leukopenia and thrombocytopenia. The overall fatality rate among the 165 cases was 33.3%, despite hospitalization and vigorous supportive care.
Assuntos
Febres Hemorrágicas Virais/epidemiologia , Febres Hemorrágicas Virais/fisiopatologia , Febres Hemorrágicas Virais/diagnóstico , Febres Hemorrágicas Virais/terapia , Humanos , Incidência , Masculino , Avaliação de Resultados em Cuidados de Saúde , Estações do Ano , Venezuela/epidemiologiaRESUMO
Rodents collected from the Venezuelan llanos (plains) during field studies of viral hemorrhagic fever were tested for evidence of hantavirus infection. Hantavirus antibody was found in one (7.7%) of 13 Oryzomys bicolor, one (3.4%) of 29 Rattus rattus, 10 (6.0%) of 166 Sigmodon alstoni and one (2.2%) of 45 Zygodontomys brevicauda. Hantavirus-specific RNA was detected in lung tissues from four antibody-positive rodents: two S. alstoni from Portuguesa State and one S. alstoni each from Cojedes and Barinas States. A hantavirus isolate (herein identified as VHV-574) was recovered from lung tissue from a hantavirus RNA-positive S. alstoni collected from Portuguesa State. The results of serological tests and analyses of small and medium RNA segment nucleotide sequence data indicated that VHV-574 represents a novel hantavirus (proposed name 'Caño Delgadito') that is distinct from all previously characterized hantaviruses. The results of analyses of nucleotide sequence data from the four hantavirus RNA-positive S. alstoni suggested that Caño Delgadito virus is widely distributed in the Venezuelan llanos.