Filogenia e filogeografia do vírus da raiva de morcegos insetívoros Nyctinomops spp. no Brasil
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Data
2017-10-18
Autores
Grisolio, Ana Paula Rodomilli
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Universidade Estadual Paulista (Unesp)
Resumo
A raiva é uma doença viral infecciosa aguda, de caráter zoonótico, que atinge todas as espécies de mamíferos. No meio urbano, os cães e os morcegos, em especial os insetívoros e os frugívoros, são vistos como principais agentes transmissores da enfermidade, e ao pensar na sua interação com os seres humanos, os cuidados se intensificam, tendo em vista o risco de propagação da doença. O avanço nos estudos epidemiológicos baseados na análise molecular do vírus da raiva, nas últimas décadas, permitiu a identificação de reservatórios e a distribuição geográfica das variantes. No entanto, dada a constante adaptação genética do vírus aos seus hospedeiros, o presente estudo objetivou realizar uma análise filogenética e filogeográfica do vírus da raiva (RABV) de amostras provenientes de diferentes estados do Brasil, identificados como positivos pelo Instituto Pasteur, São Paulo/SP. Para tanto, foram analisadas sequências parciais do gene codificador da nucleoproteína de 71 amostras de Sistema Nervoso Central (SNC) de morcegos insetívoros Nyctinomops spp. Observou-se na análise filogenética que 65 das 71 amostras agruparam-se em um mesmo clado juntamente com amostras de morcegos insetívoros do banco de dados, representando uma variante específica desse gênero de quiróptero. As outras seis amostras dividiram-se em outros clados mostrando haver proximidade genética entre isolados de morcegos hematófagos e não hematófagos e também entre estes e outros mamíferos silvestres. Ainda foi possível encontrar um morcego proveniente do Município de Tabuleiro do Norte/RN com RABV pertencente à variante relacionada ao cachorrodo- mato (Cerdocyon thous), indicando ser esse um primeiro relato dessa transmissão. Na filogeografia, observou-se a importância que a localização geográfica e as características de relevo exercem na distribuição das variantes do RABV, havendo predomínio de relação genética em localidades próximas e com altitudes semelhantes. As características biológicas do morcego Nyctinomops também influenciam na distribuição do vírus entre seus exemplares, pois, por ser tratar de uma espécie não migratória e que se adaptou facilmente ao ambiente urbano, nota-se uma tendência de uma linhagem do vírus circular em uma mesma região por um longo tempo. Dessa forma, as análises filogenética e filogeográfica são importantes ferramentas para ajudar a compreender a origem, a distribuição e a transmissão das diferentes variantes do RABV no Brasil, especialmente entre morcegos não hematófagos, cada vez mais importantes como reservatórios da raiva na área urbana. Assim, com esses resultados é possível auxiliar nas medidas de controle e prevenção da raiva em centros urbanos, reforçar as medidas educativas que mostrem para a população os riscos envolvidos na interação com quirópteros e outros mamíferos silvestres, fornecer subsídios para os Serviços de Vigilância Epidemiológica dos diferentes municípios e colaborar com as atividades do Laboratório de Biologia Molecular do Instituto Pasteur em São Paulo/SP, referência em diagnóstico e em estudos sobre a raiva no Brasil.
Rabies is an acute infectious viral disease of a zoonotic character that affects all the mammalian species. In the urban area, dogs and bats, especially the insetivorous and frugivorous, are seen as the main transmitters of the disease, and when their interaction with humans is analyzed, care is intensified according to the risk of rabies propagation. Advances in epidemiological studies based on the molecular analysis of the rabies virus in recent decades have allowed the identification of reservoirs and the geographical distribution of variants. However, given the constant genetic adaptation of the virus to the hosts, the present study aimed to perform a phylogenetic and phylogeographic analysis of rabies virus (RABV) from different states of Brazil, identified as positive by Pasteur Institute, São Paulo/SP. For this, partial sequences of the nucleoprotein gene of 71 samples from insectivorous bats Nyctinomops spp were analyzed. It was observed in the phylogenetic analysis that 65 of the 71 samples were grouped in the same cluster with samples of insectivorous bats from the GenBank database, representing a specific variant of this bat genus. The other six samples were divided into other clusters showing genetic proximity between hematophagous and nonhematophagous bats isolates and also between these and other wild mammals. It was possible to find a bat from the municipality of Tabuleiro do Norte/RN with RABV belonging to a variant related to crab-eating foxes (Cerdocyon thous), indicating that this result can be a first report of this transmission. In phylogeography, it was observed the importance that the geographical location and the relief characteristics have in the distribution of RABV variants, with a predominance of genetic relation in nearby localities with similar altitudes. The biological characteristics of the Nyctinomops bat also influence the distribution of the virus among its specimens because it is a non-migratory species and easily adapted to the urban area, which causes a tendency of a virus lineage to circulate in the same region for a long time. Thus, phylogenetic and phylogeographic analyzes showed to be important tools to help understand the origin, distribution and transmission of different variants of RABV in Brazil, especially among non-hematophagous bats, which are increasingly important as hosts of rabies in the urban area. The results allow to assist in measures of control and prevention of rabies in urban areas; to reinforce educational activities that show to the population the risks involved in interacting with bats and other wild mammals; to provide subsidies for the Epidemiological Surveillance Services from different Brazilian municipalities and to collaborate with the activities of the Molecular Biology Laboratory from Pasteur Institute, São Paulo/SP, reference in diagnosis and rabies studies in Brazil.
Rabies is an acute infectious viral disease of a zoonotic character that affects all the mammalian species. In the urban area, dogs and bats, especially the insetivorous and frugivorous, are seen as the main transmitters of the disease, and when their interaction with humans is analyzed, care is intensified according to the risk of rabies propagation. Advances in epidemiological studies based on the molecular analysis of the rabies virus in recent decades have allowed the identification of reservoirs and the geographical distribution of variants. However, given the constant genetic adaptation of the virus to the hosts, the present study aimed to perform a phylogenetic and phylogeographic analysis of rabies virus (RABV) from different states of Brazil, identified as positive by Pasteur Institute, São Paulo/SP. For this, partial sequences of the nucleoprotein gene of 71 samples from insectivorous bats Nyctinomops spp were analyzed. It was observed in the phylogenetic analysis that 65 of the 71 samples were grouped in the same cluster with samples of insectivorous bats from the GenBank database, representing a specific variant of this bat genus. The other six samples were divided into other clusters showing genetic proximity between hematophagous and nonhematophagous bats isolates and also between these and other wild mammals. It was possible to find a bat from the municipality of Tabuleiro do Norte/RN with RABV belonging to a variant related to crab-eating foxes (Cerdocyon thous), indicating that this result can be a first report of this transmission. In phylogeography, it was observed the importance that the geographical location and the relief characteristics have in the distribution of RABV variants, with a predominance of genetic relation in nearby localities with similar altitudes. The biological characteristics of the Nyctinomops bat also influence the distribution of the virus among its specimens because it is a non-migratory species and easily adapted to the urban area, which causes a tendency of a virus lineage to circulate in the same region for a long time. Thus, phylogenetic and phylogeographic analyzes showed to be important tools to help understand the origin, distribution and transmission of different variants of RABV in Brazil, especially among non-hematophagous bats, which are increasingly important as hosts of rabies in the urban area. The results allow to assist in measures of control and prevention of rabies in urban areas; to reinforce educational activities that show to the population the risks involved in interacting with bats and other wild mammals; to provide subsidies for the Epidemiological Surveillance Services from different Brazilian municipalities and to collaborate with the activities of the Molecular Biology Laboratory from Pasteur Institute, São Paulo/SP, reference in diagnosis and rabies studies in Brazil.
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Palavras-chave
Biologia molecular, Quirópteros, Rabies lyssavirus, Vigilância epidemiológica, Molecular biology, Bats, Epidemiological surveillance