RESUMO
Venezuelan equine encephalitis virus (VEEV) is an emerging pathogen of equids and humans, but infection of its rodent reservoir hosts has received little study. To determine whether responses to infection vary among geographic populations, we inoculated 3 populations of cotton rats with 2 enzootic VEEV strains (Co97-0054 [enzootic ID subtype] and 68U201 [enzootic IE subtype]). The 3 populations were offspring from wild-caught cotton rats collected in a VEE-enzootic area of south Florida, USA; wild-caught cotton rats from a non-VEE-enzootic area of Texas, USA; and commercially available (Harlan) colony-reared cotton rats from a non-VEE-enzootic region. Although each population had similar early viremia titers, no detectable disease developed in the VEE-sympatric Florida animals, but severe disease and death affected the Texas and Harlan animals. Our findings suggest that the geographic origins of cotton rats are important determinants of the outcome of VEE infection and reservoir potential of these rodents.
Assuntos
Vírus da Encefalite Equina Venezuelana/crescimento & desenvolvimento , Encefalomielite Equina Venezuelana/veterinária , Encefalomielite Equina Venezuelana/virologia , Doenças dos Roedores/virologia , Sigmodontinae/virologia , Animais , Reservatórios de Doenças/virologia , Encefalomielite Equina Venezuelana/epidemiologia , Encefalomielite Equina Venezuelana/imunologia , Feminino , Florida/epidemiologia , Masculino , Ratos , Doenças dos Roedores/epidemiologia , Doenças dos Roedores/imunologia , Sigmodontinae/imunologia , Texas/epidemiologia , Viremia/epidemiologia , Viremia/imunologia , Viremia/virologiaRESUMO
Primary cultures of embryonic murine neurons and newborn mouse astrocytes were inoculated with West Nile virus (WNV) strain NY385-99 to compare the pathogenesis of WNV infection in these types of CNS cells. Two different outcomes were observed. WNV infection in the neurons was rapidly progressive and destructive; within 5 days, all of the neurons were destroyed through apoptosis. WNV infection in the astrocytes evolved more slowly and did not seem to be highly lethal to the cells. The infected astrocytes continued to produce infectious virus (10(4.6)-10(6.5) PFU/mL) for 114 days, in a permissive, persistent infection. During this period, WNV antigen could be shown in the cytoplasm of the infected astrocytes by immunocytochemical assay, transmission electron microscopy of ultrathin sections, and in the cell culture medium by complement fixation test. Our results with this in vitro experimental murine cell model indicate that astrocytes can develop chronic or persistent infection with WNV, suggesting that these cells may play a role in the maintenance of WNV in the CNS.
Assuntos
Astrócitos/virologia , Neurônios/virologia , Vírus do Nilo Ocidental/fisiologia , Animais , Antígenos Virais/análise , Apoptose , Astrócitos/ultraestrutura , Células Cultivadas , Testes de Fixação de Complemento , Efeito Citopatogênico Viral , Testes de Hemaglutinação , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Camundongos , Camundongos Endogâmicos ICR , Neurônios/ultraestrutura , Replicação Viral , Vírus do Nilo Ocidental/imunologia , Vírus do Nilo Ocidental/patogenicidade , Vírus do Nilo Ocidental/ultraestruturaRESUMO
An Oropouche virus strain was isolated from a novel host (Callithrix sp.) in Arinos, Minas Gerais State, southeastern Brazil. The virus was identified by complement fixation test and confirmed by reverse transcription-polymerase chain reaction. Phylogenetic analysis identified this strain as a genotype III isolate previously recognized only in Panama.
Assuntos
Infecções por Bunyaviridae/veterinária , Callithrix/virologia , Doenças dos Macacos/virologia , Orthobunyavirus/classificação , Orthobunyavirus/isolamento & purificação , Animais , Brasil/epidemiologia , Infecções por Bunyaviridae/epidemiologia , Infecções por Bunyaviridae/virologia , Testes de Fixação de Complemento , Humanos , Camundongos , Orthobunyavirus/genética , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
This paper reports the results of serologic, structural, biochemical, and genetic studies indicating that Araguari virus, a previously unassigned viral agent, is a member of the family Orthomyxoviridae and genus Thogotovirus. Araguari virus has six RNA fragments; biologically, it shares several properties with other viruses in the family Orthomyxoviridae. Nucleotide sequencing of the RNA segments 4 (glycoprotein) and 5 (nucleoprotein) of Araguari virus aligned with the orthomyxoviruses, showing the closest relationship with Thogoto virus (sequence similarity = 61.9% and 69.1%, respectively, for glycoprotein and nucleoprotein), but also sharing a more distant similarity with Dhori and Influenza C viruses, especially for the glycoprotein gene. Based on these results, we propose that Araguari virus should be assigned as a new member of the family Orthomyxoviridae and genus Thogotovirus.
Assuntos
Orthomyxoviridae/classificação , Animais , Sequência de Bases , Chlorocebus aethiops , Testes de Fixação de Complemento , DNA Complementar/análise , Testes de Inibição da Hemaglutinação , Marsupiais/virologia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Microscopia Imunoeletrônica , Dados de Sequência Molecular , Orthomyxoviridae/genética , Orthomyxoviridae/ultraestrutura , RNA Viral/análise , Alinhamento de Sequência , Células VeroRESUMO
Epizootics of encephalitis in El Salvador killed 203 equines between November 2001 and April 2003. During an investigation of the outbreaks, 18 (25%) of 73 serum samples collected from stablemates of deceased animals in 2003 had antibodies to West Nile virus. Ten of these infections were confirmed by plaque reduction neutralization tests, suggesting West Nile virus has extended its range and spread to Central America.
Assuntos
Surtos de Doenças/veterinária , Doenças dos Cavalos/virologia , Febre do Nilo Ocidental/veterinária , Animais , El Salvador/epidemiologia , Ensaio de Imunoadsorção Enzimática/veterinária , Doenças dos Cavalos/epidemiologia , Cavalos , Humanos , Estações do Ano , Febre do Nilo Ocidental/epidemiologiaRESUMO
From June to December 1999, 785 serum samples were obtained from patients clinically suspected of having dengue or yellow fever. The patients were referred by public health centers distributed within the six mesoregions of Par State, Brazil. Serum samples were tested for Flavivirus antibodies by hemagglutination inhibition test and for dengue and yellow fever viruses by enzyme-linked immunosorbent assay for IgM detection. Of the sera collected, 563 (71.7%) were positive by HI test and out of these 150 (26.6%) were positive by ELISA-IgM. Dengue virus was responsible for most of the recent infections in all regions; yellow fever cases detected in the current study were restricted to the Maraj and Southeast regions.