Imunofluorescência utilizando isolados brasileiros no diagnóstico sorológico de infecção por lentivírus em caprinos

Abstract

Small ruminant lentiviruses (SRLV) are distributed worldwide and cause persistent infections in sheep and goats. The purpose of this work was to develop an indirect immunofluorescent antibody (IFA) test using Brazilian SRLV isolates for serological diagnosis of infection in goats. The IFA test was compared in its sensitivity and specificity to the AGID test in which Maedi-Visna WLC-1 strain was used as antigen. Ovine synovial secondary cell cultures infected with two goat SRLV isolates (CAEV UFRGS/Br-2 and CAEV UFRGS/Br-5) were used for the IFA. Goat serum samples (n = 239) were tested by the two tests. The AGID test detected antibodies in 129 (53.9%) serum samples. A higher number of animals was considered positive for the IFA. However, different results were obtained depending on the isolate used for the antigen preparation. When CAEV UFRGS/Br-2 was used as antigen, 216 (90.3%) serum samples tested positive, against 213 (89.1%) with CAEV UFRGS/Br-5. There was no significant statistical difference between the antigens prepared with these two isolates. The IFA had sensitivity of 94.6% and 96.9%, and specificity of 14.5 % and 20%, when CAEV UFRGS/Br-2 and CAEV UFRGS/Br-5 were used as antigens, respectively. These results demonstrate that the IFA with antigens prepared with Brazilian SRLV isolates may play an important a role as a complementary serological test for the diagnosis of infections by these agents.INDEX TERMS: Small ruminant lentiviruses, Brazilian isolates, diagnosis, indirect immunofluorescence, immunodiffusion, goats.

Ferramentas diagnósticas de Lentivirose de Pequenos Ruminantes: padronização da técnica de ELISA indireto

“…Além disso, conforme discutido por Pinheiro et al (2010), em um rebanho controlado para LVPR utilizando sempre o mesmo antígeno, pode haver o efeito de seleção entre os animais. Quando se aplica um teste com antígeno diferente daquele utilizado no programa de controle, é possível encontrar um maior número de animais positivos, além do fato de que pequenas alterações antigê-nicas podem influenciar a sensibilidade do teste de IDGA (Reischak, 2000) bem como o processamento do ELISA, no qual as lavagens com PBS contendo Tween 20 podem ocasionar a exposição de certos epítopos.…”

Early Detection of goats infected with Lentivirus Small Ruminant virus by ELISA assay

“…Because SRLV infection induce low immunological response in infected animals, highly sensitive serological techniques involving highly efficient antigen-antibody interactions are required for proper detection of viral infection. Therefore, immunoenzymatic assays (ELISA) that require only one epitope interaction per antibody are a better choice to those that demand the interaction of many epitopes per antibody (AGID;CELER et al, 1998;REISCHAK et al, 2002).…”

“…The risk of the late seroconversion always exists and is a characteristic of lentiviruses in general, and it is therefore recommended to double-check the diagnosis of the SRLV with multiple different assays. This scheme is routinely used in the serological diagnosis of another severe lentivirus, Human immunodeficiency virus, where complementary serological tests such as WB or IFI confirm the diagnosis for those sera that are classified as reactive or indeterminate ( REISCHAK et al, 2002). These serological assays, WB and IFI, were performed in parallel to ELISA test and showed a high correlation with the ELISA results.…”

Produção de antígeno viral para o sorodiagnóstico da artrite-encefalite caprina utilizando um teste imunoenzimático (ELISA)

“…antigênicas nas proteínas e glicoproteínas também podem influenciar a sensibilidade dos testes (CELER JR. et al, 1998;REISCHAK;RAVAZZOLO;MOOJEN, 2002). Portanto, este trabalho relata a produção de um antígeno viral de fácil obtenção, com a utilização de uma metodologia simples e de baixo custo, a qual, empregada em um teste ELISA indireto, permitiu a obtenção de um teste sensível, específico e de detecção precoce de anticorpos para CAEV em caprinos.…”