Serological survey of bluetongue virus in sheep from Minas Gerais / Inquérito sorológico do vírus da língua azul em ovinos de Minas Gerais

Bluetongue is an infectious, non-contagious disease that affects domestic and wild ruminants, caused by a virus from the Orbivirus genus, Reoviridae family, transmitted by arthropod vectors of the Culicoides genus. This paper aims to be the first serological survey of bluetongue in sheep from the Meso-regions of Campo das Vertentes and South and Southeast of Minas Gerais. Samples were collected from sheep from different properties. The serum samples were submitted to Agar Gel Immunodiffusion (AGID) and competitive Enzyme-Linked Immunosorbent Assay (cELISA). 303 serum samples were submitted to AGID and cELISA. In these samples, 164 (54.13%) were positive in the AGID technique, and 171 (56.44%) positive in the cELISA technique, with an almost perfect agreement between the techniques (kappa index = 0.887). In all visited properties, positive animals have been found in the herd. Animals acquired from properties of the studied mesoregions were more likely to be positive in IDGA and cELISA tests than animals acquired from properties in other regions of Brazil (p<0.001). These results suggest that bluetongue virus (BTV) is widespread in the mesoregions of Campo das Vertentes and South and Southeast of Minas Gerais.(AU)

A língua azul (LA) é uma doença infecciosa, não contagiosa, que acomete ruminantes domésticos e silvestres, causada por um vírus do gênero Orbivirus da família Reoviridae, transmitida por vetores artrópodes do gênero Culicoides. O presente estudo representa o primeiro trabalho a realizar um inquérito sorológico da língua azul em rebanhos ovinos nas Mesorregiões de Campo das Vertentes e Sul e Sudoeste de Minas Gerais. Foram coletadas amostras de soro de ovinos de diferentes propriedades. As amostras de soro foram submetidas aos testes de imunodifusão em gel de ágar (IDGA) e ensaio de imunoadsorção enzimática por competição (cELISA). Ao todo 303 amostras de soro foram submetidas ao IDGA e cELISA. Dessas amostras, 164 (54,13%) foram positivas na técnica de IDGA e 171 (56,44%) positivas na técnica de cELISA, havendo concordância quase perfeita entre as técnicas (índice kappa = 0,887). Em todas as propriedades visitadas, foram encontrados animais positivos no rebanho. Animais adquiridos de propriedades das Mesorregiões estudadas, tiveram mais chances de serem positivos nos testes de IDGA e cELISA do que animais adquiridos de propriedades de outras Regiões do Brasil (p<0,001). Esses resultados sugerem que o vírus da língua azul encontra-se disseminado em ovinos nas Mesorregiões de Campo das Vertentes e Sul e Sudoeste de Minas Gerais.(AU)

Bluetongue disease in sheep: a review / O vírus da língua azul em ovinos: uma revisão

The present review aims to show the main aspects related to bluetongue virus (BTV) infection in sheep. The bluetongue (BT) is a viral, infectious, and non-contagious disease caused by a virus (BTV) of the Orbivirus genus, transmited by a hematophagous vector of the Culicoides genus, to domestic and wild ruminants, mainly to sheep, the most susceptible species. It is caused by the association of endemic with climate conditions, with high temperatures and humidity. Economic loss is directly linked to death, abortion, weight loss, loss of milk, and meat production, and, indirectly, to the restriction on the export of animals and their by-products. The study concludes that the BTV is worldwidely spread, and probably persists due to the warm and humid climate that leads to the proliferation of Culicoides sp., being necessary to adopt measures that reduce the risk factors associated to the BTV infection.(AU)

A presente revisão objetivou apresentar os principais aspectos relacionados à infecção causada pelo vírus da língua azul em ovinos. A língua azul é uma doença viral, infecciosa e não contagiosa, causada por um vírus (BTV) do gênero Orbivírus, transmitida por meio de vetores hematófagos do gênero Culicoides a ruminantes domésticos e selvagens, principalmente aos ovinos, a espécie mais susceptível. A infecção ocorre de forma endêmica, associada a condições climáticas com elevada temperatura e umidade. As perdas econômicas estão ligadas diretamente à morte, ao abortamento, à perda de peso, à perda na produção de leite e carne, e, indiretamente, devido à restrição na exportação de animais e seus subprodutos. O estudo conclui que a língua azul está disseminada mundialmente e persiste, provavelmente, devido ao clima quente e úmido que propicia a proliferação de Culicoides sp., sendo necessário adotar medidas que diminuam os fatores de risco associados à infecção pelo vírus.(AU)

Frequência de anticorpos contra o vírus da língua azul em ovinos do estado do Ceará, Brasil / Antibodies against the bluetongue virus in sheep flocks of Ceará state, Brazil

O objetivo deste trabalho foi avaliar a ocorrência de ovinos soropositivos para o vírus da línguaazul (VLA) no Estado do Ceará, Brasil, e analisar as proteínas imunogênicas das cepas virais circulantes nesses rebanhos. O teste de imunodifusão em gel de agarose (IDGA) foi utilizado para pesquisar 271 amostras de soro oriundas de 16 rebanhos. Os resultados demonstraram que 27,3% (74/271) das amostras analisadas apresentaram anticorpos contra o agente e 68,8% (11/16) das propriedades tiveram animais positivos. O immunoblotting (IB) foi utilizado para analisar as proteínas imunogênicas do VLA a partir dos soros de animais positivos no IDGA. Os soros demonstraram forte reação contra a proteína viral VP2. Para o VLA, das sete proteínas estruturais, a VP2 é a principal a estimular a resposta imune protetora. Concluiu-se que a soropositividade para a língua azul (LA) nos rebanhos ovinos estudados no Ceará é alta, apesar dos animais não apresentarem sinais clínicos, indicativo de que o vírus ocorra de forma endêmica. Além disso, a resistência à doença apresentada pelos animais pode estar relacionada com a forte reação imunológica desses à proteína VP2. Sendo assim, outros estudos são necessários para melhor esclarecer a situação epidemiológica da LA no país, através da identificação dos vetores e sorotipos virais circulantes nas diferentes regiões.

Antibodies against the bluetongue virus in sheep flocks of Ceará state, Brazil. The objective of this work was to verify the occurrence of sheep serologically positive for bluetongue virus (BTV) in the state of Ceará, Brazil, and analyze immunogenic proteins of circulating viral strains in these flocks. The agar gel immunodifusion test (AGID) was used to examine 271 serum samples from 16 herds. The results demonstrated that 27.3% (74/271) ofthe analyzed samples presented antibodies for the agent, and that 68.8% (11/16) of the propertiespresented positive animals. Immunoblotting (IB) was used to analyze the immunogenicproteins of BTV derived from AGID positive sera. Sera showed strong reaction against viral protein VP2. Of the seven BTV structural proteins, VP2 is the major protein to elicit protective immuneresponses. It was concluded that bluetongue (BT) seropositivity in sheep flocks studied in Ceará is high, despite that the animal's do not show clinical signs, indicating that it occurs in an endemic form. The animals’ resistance to the disease may be related to the strong immune response to the protein VP2. Therefore, further studies are needed to better clarify the epidemiological situation of BT in Brazilian sheep flocks, through the identification of viral vectors and serotypes circulating in different regions.

Anticorpos contra o vírus da língua azul em rebanhos ovinos da microrregião de Juazeiro, Bahia / Antibodies against the bluetongue virus in sheep flocks of Bahia state, Brazil

O objetivo desta pesquisa foi verificar a frequência de ovinos soropositivos para o vírus da língua azul na microrregião de Juazeiro, Bahia. O teste de imunodifusão em gel de ágar (IDGA) foi utilizado para pesquisar 469 amostras de soro oriundas de 58 rebanhos. Durante as colheitas, um questionário foi aplicado a cada criador a fim de se obter dados sobre o sistema de criação e correlacioná-los com a sorologia. Os resultados demonstraram que 0,43% (2/469) das amostras analisadas apresentaram anticorpos contra o agente. Esta região é caracterizada pelo clima semiárido e pela predominância do tipo de exploração extensiva, com presença de animais nativos, mestiços e sem raça definida para produção de carne e pele, com baixa produtividade e tecnificação.

The objective of this work was to verify the frequency of sheep with positive serology for Bluetongue virus in the micro-region of Juazeiro, Bahia State, Brazil. The agar gel immunodifusion test (AGID) was used to examine 469 serum samples of 58 herds. During collection, an epidemiological questionnaire was applied to each farmer. The results demonstrated that 0.43% (2/469) of the analyzed samples presented antibodies for the agent. This region is characterized by a semi-arid climate, and the predominant livestock management system is the extensive one, with a presence of native and crossbred animals, aiming at the production of meat and fleece, with low productivity and technification.

Determinación electroforética del genoma de un virus asociado a encefalitis equina en el departamento de San Martín / Electrophoretic determination genome of a virus associated with equine encephalitis in the department of San Martin

La encefalitis equina es una enfermedad viral que afecta al sistema nervioso de caballos y otros mamíferos (incluyendo humanos). Desde 1984 se han detectado varios casos en el departamento de San Martín con sintomatología e histopatología semejantes a los alfavirus (genoma de 1 segmento de RNA), sin embargo los estudios serológicos y caracterización de microscopía sugerían la presencia de un orbivirus (genoma de 10 segmentos de RNA). Hipótesis inesperada por la ausencia de orbivirus asociados con encefalitis equina en el nuevo continente. El objetivo principal del proyecto es dilucidar a nivel molecular e identificar la naturaleza del virus asociado a la encefalitis equina en el departamento de San Martín. Utilizando las técnicas de electroforesis se determinó con mayor precisión el tipo de virus involucrado. Los análisis de ARN de aislamiento virales de animales enfermos y sanos colectados en 1997 de una zona endémica y de animales aparentemente sanos colectados en 2002 de la misma zona confirmaron que el genoma está constituido en 10 segmentos de ARN de cadena doble correspondiente al género orbivirus de la Familia de los Reoviridae. Estos datos determinan que el virus aislado en el departamento de San Martín es un orbivirus y que además es el primero causando encefalitis equina en Sudamérica.

The equine encephalitis is a viral disease that affects nervous system of horses and other mammals (including humans). From 1984 several cases with symptomatology and histopathology similar with Alphavirus (1 segment RNA genome) have been detected in San Martin Deparment, nevertheless serology studies and characterization of electronic microscopy indicated compatibility with an orbivirus (10 segment RNA genome). The molecular characterization using electrophoresis will unequivocally determine the type of virus. The RNA analysis of viral isolations from healthy and ill animals collected in 1997 of an endemic zone and animals apparently healthy collected in 2002 from the same zone confirmed that the viral genome is constituted by 10 segments of RNA corresponding to orbivirus genus of the Family Reoviridae. These data reveal that the virus isolated in the San Martin Department is an orbivirus, the first one associated to equine encephalitis in the South America.

Apoptosis in Vero cells infected with Akabane, Aino and Chuzan virus

Akabane, Aino and Chuzan virus are arthropod-borne (arbo)viruses mainly associated with reproductive failures in cattle. We investigated apoptosis in Vero cells (C-1586) infected with Akabane, Aino and Chuzan virus. The fragmentation of chromosomal DNA was simultaneously detected with the progress of cytopathic effect from 48 hr to 72 hr post infection, depending on viruses. Although the treatment of cycloheximide blocked apoptosis in Vero cells infected with three viruses, actinomycin D did not prevent DNA oligomerization, thus indicating that de novo viral protein synthesis is critical for viral apoptosis. In addition, the activation of caspase-3 was also detected in Vero cells by indirect fluorescent assay. From the present results, it is of future interest whether apoptotic characteristics of these viruses are related to pathogenecity in vivo.

Investigation of Arboviruses in Lancang river down-stream area in Yunnan province / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To investigate the epidemic state of arboviruses in the downstream area of Lancang river in Yunnan province.</p><p><b>METHODS</b>Mosquitoes were collected from Lancang river downstream area (including Lancang county and Simao city) during summer in 1998 and stored in liquid nitrogen after classification. The mosquito pools were homogenized and centrifuged, then the supernatant was inoculated into C6/36 cells for virus isolation. New isolates were identified by neutralization test(NT), ELISA, immunofluorescence assay(IFA) and polyacrylamid gel electrophoresis(PAGE).</p><p><b>RESULTS</b>Totally 22 isolates of arbovirus were obtained from 233 mosquito pools by inoculation of C6/36 cells and positive rate of the isolation was 9.4%. Ten strains were resistant to both ether and 5 prime-IDU. So they were non-enveloped double-stranded (ds) RNA virus. Twelve segmented RNAs were shown by PAGE and PAGE profiles from the ten strains were 6-6 with minor variation. The isolates can be neutralized by immunized mouse ascites fluid of BJ95-75 strains of coltivirus by NT, and reacted with monoclonal antibody against BJ95-75 by ELISA. These viruses were identified as coltivirus. Nine isolates were sensitive to ether and resistant to 5 prime-IDU. So they were non-enveloped RNA viruses. PAGE showed 10 segmented RNA, and they were identified to be orbiviruses. Three isolations were sensitive to ether. One of them can be neutralized with JEV A2 strain antibody by NT and was positive to the homologous antibody by IFA. It was identified being strain of JE virus. One strain(YN92-4) can be reacted with anti-bunyavirus group specific immune ascites fluid by both IFA and ElISA, but reacted neither with anti-alpha virus group, nor with anti-flavivirus group JE virus ascites fluid. The virions are spherical and about 87 nm in diameter with surface projections by negative staining. Conclusion Twenty-two isolates have been obtained from wild caught-mosquitoes of Lancang river down-stream area in Yunnan province. Among them ten, nine, one and one were identified as coltivirus, orbivirus, JE virus and bunyavirus, respectively. One is under identification. This is the first report on bunyavirus isolated from mosquitoes in China.</p>

Anticorpos contra o vírus da língua azul em bovinos do sertäo da Paraíba / Antibodies to bluetongue virus in bovines of Paraíba State, Brazil

In June of 1997 the prevalence of antibodies to bluetongue virus was between 3.94 and 4.82 per cent in 137 bovine serum samples from 12 herds in Paraíba State, Brazil. This is the first report of antibodies to bluetongue virus in Paraiba State herds