RESUMO
The Flavivirus genus includes a number of important viruses that are pathogenic to humans and animals and are responsible for outbreaks across the globe. Integrins, a family of heterodimeric transmembrane molecules expressed in all nucleated cells mediate critical functions of cell physiology and cell cycle. Integrins were previously postulated to be involved in flavivirus entry and to modulate flavivirus replication efficiency. In the present study, mouse embryonic fibroblasts (MEF), lacking the expression of αVß3 integrin (MEF-αVß3-/-), were infected with four different flaviviruses, namely yellow fever virus (YFV), West Nile virus (WNV), Usutu virus (USUV) and Langat virus (LGTV). The effects of the αVß3 integrin absence in double-knockout MEF-αVß3-/- on flavivirus binding, internalization and replication were compared to the respective wild-type cells. Binding to the cell surface for all four flaviviruses was not affected by the ablation of αVß3 integrin, whereas internalization of USUV and WNV was slightly affected by the loss of αVß3 integrin expression. Most interestingly, the deletion of αVß3 integrin strongly impaired replication of all flaviviruses with a reduction of up to 99% on virus yields and a strong reduction on flavivirus anti-genome RNA synthesis. In conclusion, our results demonstrate that αVß3 integrin expression in flavivirus-susceptible cell lines enhances the flavivirus replication.
Assuntos
Flavivirus/fisiologia , Integrina alfaVbeta3/metabolismo , Replicação Viral , Animais , Linhagem Celular , Vírus da Encefalite Transmitidos por Carrapatos/genética , Vírus da Encefalite Transmitidos por Carrapatos/fisiologia , Fibroblastos/virologia , Flavivirus/genética , Genoma Viral , Integrina alfaVbeta3/genética , Camundongos , RNA Viral/genética , RNA Viral/metabolismo , Ligação Viral , Internalização do Vírus , Vírus do Nilo Ocidental/genética , Vírus do Nilo Ocidental/fisiologia , Vírus da Febre Amarela/genética , Vírus da Febre Amarela/fisiologiaRESUMO
Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country.
Assuntos
Anticorpos Antivirais/sangue , Doenças dos Cavalos/epidemiologia , Febre do Nilo Ocidental/veterinária , Vírus do Nilo Ocidental/imunologia , Animais , Brasil/epidemiologia , Ensaio de Imunoadsorção Enzimática/veterinária , Doenças dos Cavalos/diagnóstico , Doenças dos Cavalos/virologia , Cavalos , Testes de Neutralização , Estudos Soroepidemiológicos , Febre do Nilo Ocidental/diagnóstico , Febre do Nilo Ocidental/epidemiologia , Vírus do Nilo Ocidental/isolamento & purificaçãoRESUMO
INTRODUCTION: West Nile virus (WNV) is a flavivirus with a natural cycle involving mosquitoes and birds. Over the last 11 years, WNV has spread throughout the Americas with the imminent risk of its introduction in Brazil. METHODS: Envelope protein domain III of WNV (rDIII) was bacterially expressed and purified. An enzyme-linked immunosorbent assay with WNV rDIII antigen was standardized against mouse immune fluids (MIAFs) of different flavivirus. RESULTS: WNV rDIII reacted strongly with St. Louis encephalitis virus (SLEV) MIAF but not with other flaviviruses. CONCLUSIONS: This antigen may be a potentially useful tool for serologic diagnosis and may contribute in future epidemiological surveillance of WNV infections in Brazil.
Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Proteínas Recombinantes/imunologia , Proteínas do Envelope Viral/imunologia , Vírus do Nilo Ocidental/imunologia , Animais , Brasil , Ensaio de Imunoadsorção Enzimática , CamundongosRESUMO
INTRODUCTION: West Nile virus (WNV) is a flavivirus with a natural cycle involving mosquitoes and birds. Over the last 11 years, WNV has spread throughout the Americas with the imminent risk of its introduction in Brazil. METHODS: Envelope protein domain III of WNV (rDIII) was bacterially expressed and purified. An enzyme-linked immunosorbent assay with WNV rDIII antigen was standardized against mouse immune fluids (MIAFs) of different flavivirus. RESULTS: WNV rDIII reacted strongly with St. Louis encephalitis virus (SLEV) MIAF but not with other flaviviruses. CONCLUSIONS: This antigen may be a potentially useful tool for serologic diagnosis and may contribute in future epidemiological surveillance of WNV infections in Brazil.