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
In 1995, an outbreak of hantavirus pulmonary syndrome occurred in the central Paraguayan chaco. The primary reservoir of the virus, Laguna Negra virus, was identified as the vesper mouse, Calomys laucha. Over a 15-month period, we collected 1,090 small mammals at 12 locations representing 4 habitats common in the central Paraguayan chaco. Calomys laucha was common in agricultural habitats and uncommon in the native forest habitat. Populations of C. laucha were greater during the dry season months and declined during the wet season. A total of 643 small mammals were tested for antibodies cross-reactive to Sin Nombre virus. All of the antibody-positive animals were C. laucha (crude antibody prevalence ratio 12.1% [25 of 206]). Antibody prevalence ratio increased with body size and was more common among male (18%; n = 115) than among female (4%; n = 96) vesper mice. Antibody prevalence ratio was highest among animals from cropland habitats (18%; n = 72), followed by thorn scrub (13%; n = 46) and pastureland (7%; n = 81) and may be positively correlated to the proportion of C. laucha in the small mammal community. These data suggest that community-level dynamics, in addition to population-level dynamics, may be involved in the transmission of the virus through natural populations of vesper mice.
Assuntos
Anticorpos Antivirais/sangue , Reservatórios de Doenças/veterinária , Síndrome Pulmonar por Hantavirus/epidemiologia , Roedores/virologia , Vírus Sin Nombre/imunologia , Animais , Surtos de Doenças , Meio Ambiente , Humanos , Paraguai/epidemiologia , Prevalência , Chuva , Estações do Ano , Vírus Sin Nombre/isolamento & purificaçãoRESUMO
Between 1993 and 1998, 10 cases of clinical hantavirus infection were diagnosed in Brazil. Hantavirus-specific IgM, or positive immunohistochemical analysis for hantavirus antigen, or positive reverse transcription-polymerase chain reaction results for hantavirus RNA were used to confirm nine of these cases; eight were hantavirus pulmonary syndrome (HPS), and one was mild hantavirus disease. The remaining clinical case of hantavirus infection was fatal, and no tissue was available to confirm the diagnosis. During the first 7 months of 1998, five fatal HPS cases caused by a Sin Nombre-like virus were reported from three different regions in the State of São Paulo, Brazil: two in March (Presidente Prudente Region), two in May (Ribeirão Preto Region), and one in July (Itapecerica da Serra Region). Epidemiologic, ecologic, and serologic surveys were conducted among case contacts, area residents, and captured rodents in five locations within the State of São Paulo in June of 1998. Six (4.8%) of 125 case contacts and six (5.2%) of 116 area residents had IgG antibody to Sin Nombre virus (SNV) antigen. No case contacts had a history of HPS-compatible illness, and only one area resident reported a previous acute respiratory illness. A total of 403 rodents were captured during 9 nights of trapping (1969 trap nights). All 27 rodents that were found to be positive for IgG antibody to SNV antigen were captured in crop border and extensively deforested agricultural areas where four of the 1998 HPS case-patients had recently worked. The IgG antibody prevalence data for rodents suggest that Bolomys lasiurus and perhaps Akodon sp. are potential hantavirus reservoirs in this state of Brazil.
Assuntos
Anticorpos Antivirais/sangue , Reservatórios de Doenças , Síndrome Pulmonar por Hantavirus/epidemiologia , Orthohantavírus/imunologia , Doenças dos Roedores/virologia , Zoonoses , Adolescente , Adulto , Animais , Antígenos Virais/imunologia , Brasil/epidemiologia , Reservatórios de Doenças/veterinária , Evolução Fatal , Feminino , Orthohantavírus/isolamento & purificação , Infecções por Hantavirus/epidemiologia , Infecções por Hantavirus/virologia , Síndrome Pulmonar por Hantavirus/virologia , Humanos , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Masculino , Pessoa de Meia-Idade , Prevalência , Doenças dos Roedores/imunologia , Roedores , Estudos SoroepidemiológicosRESUMO
Hantavirus pulmonary syndrome (HPS), a severe respiratory disease with high mortality caused by rodent-borne hantaviruses, has previously been identified in the United States and Canada as well as central and southern South America. In late 1999 and early 2000, an outbreak of acute illness compatible with HPS was reported in Los Santos, Panama, with the death of 3 of the 12 (25%) suspected cases. Hantavirus-specific antibodies were detected in patient sera, and virus RNA was detected by reverse transcriptase-polymerase chain reaction. Sequence analysis of virus genome N-, G1-, and G2-encoding fragments showed this to be a novel hantavirus, Choclo virus. Serologic and virus genetic analyses of rodents trapped in the area showed Oligoryzomys fulvescens to be the likely reservoir for the HPS-associated Choclo virus. In addition, Zygodontomys brevicauda rodents were shown to harbor another genetically unique hantavirus, Calabazo virus.
Assuntos
Reservatórios de Doenças , Síndrome Pulmonar por Hantavirus/virologia , Orthohantavírus/classificação , Filogenia , Animais , Canadá , Primers do DNA , Genoma Viral , Orthohantavírus/genética , Orthohantavírus/isolamento & purificação , Síndrome Pulmonar por Hantavirus/classificação , Humanos , Nucleocapsídeo/genética , Panamá , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sorotipagem , América do Sul , Estados UnidosRESUMO
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
An outbreak of 25 cases of Andes virus-associated hantavirus pulmonary syndrome (HPS) was recognized in southern Chile from July 1997 through January 1998. In addition to the HPS patients, three persons with mild hantaviral disease and one person with asymptomatic acute infection were identified. Epidemiologic studies suggested person-to-person transmission in two of three family clusters. Ecologic studies showed very high densities of several species of sigmodontine rodents in the area.
Assuntos
Surtos de Doenças , Síndrome Pulmonar por Hantavirus/epidemiologia , Orthohantavírus , Adulto , Pré-Escolar , Chile/epidemiologia , Feminino , Síndrome Pulmonar por Hantavirus/patologia , Síndrome Pulmonar por Hantavirus/fisiopatologia , Humanos , MasculinoRESUMO
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
Since the initial description in 1993 of hantavirus pulmonary syndrome and its novel aetiological agent, Sin Nombre virus, our knowledge of the epidemiology of New World hantaviruses has continued to evolve. After the identifying outbreak in the southwestern US, four hantaviruses have been identified in North America with specific rodent hosts and associated with a number of sporadic cases. This stability of case recognition in North America is in contrast to the multiple outbreaks and endemic cases in South America. Despite a plethora of New World hantaviruses and new evidence of person-to-person transmission, the ecological and personal determinants of this human infection remain a mystery.
Assuntos
Síndrome Pulmonar por Hantavirus/diagnóstico , Ecologia , Orthohantavírus , Síndrome Pulmonar por Hantavirus/epidemiologia , Síndrome Pulmonar por Hantavirus/transmissão , Humanos , América do Norte/epidemiologia , América do Sul/epidemiologiaRESUMO
A large outbreak of hantavirus pulmonary syndrome (HPS) recently occurred in the Chaco region of Paraguay. Using PCR approaches, partial virus genome sequences were obtained from 5 human sera, and spleens from 5 Calomys laucha rodents from the outbreak area. Genetic analysis revealed a newly discovered hantavirus, Laguna Negra (LN) virus, to be associated with the HPS outbreak and established a direct genetic link between the virus detected in the HPS cases and in the C. laucha rodents, implicating them as the primary rodent reservoir for LN virus in Paraguay. Virus isolates were obtained from two C. laucha, and represent the first successful isolation of a pathogenic South American hantavirus. Analysis of the prototype LN virus entire S and M and partial L segment nucleotide and deduced amino acid sequences showed that this virus is unique among the Sigmodontinae-borne clade of hantaviruses. Analysis of PCR fragments amplified from a serum sample from a Chilean HPS patient, who had recently traveled extensively in Bolivia (where C. laucha are known to occur), revealed an LN virus variant that was approximately 15% different at the nucleotide level and identical at the deduced amino acid level relative to the Paraguayan LN virus. These data suggest that LN virus may cause HPS in several countries in this geographic region.