Ciência Rural (Apr 2010)
Comparação dos testes de virusneutralização contra os genótipos 1 e 2 do vírus da diarreia viral bovina (BVDV-1 e BVDV-2) em bovinos de rebanhos naturalmente infectados Comparison of virusneutralization tests against genotypes 1 and 2 of the bovine viral diarrhoea virus (BVDV-1 and BVDV-2) in cattle of naturally infected herds
Abstract
Os resultados dos testes de virusneutralização (VN) contra os genótipos do vírus da diarreia viral bovina (BVDV-1 e BVDV-2), bem como os respectivos títulos de anticorpos, foram comparados em 1.925 amostras de soro sanguíneo obtidas de rebanhos bovinos naturalmente infectados e não vacinados contra o BVDV, provenientes dos Estados de São Paulo e Minas Gerais. A proporção de amostras reagentes entre os genótipos foi analisada pelo Teste de McNemar, e os títulos de anticorpos das amostras reagentes ao BVDV-1 e ao BVDV-2 foram comparados pelo Teste de Wilcoxon. Não foi verificada discordância na proporção de bovinos reagentes ao BVDV-1 e ao BVDV-2 (P>0,05). No entanto, houve discordância entre os títulos de anticorpos detectados nos testes de VN contra os genótipos 1 e 2 do BVDV (PThe virusneutralization test (VN) results against bovine viral diarrhoea virus genotypes (BVDV-1 and BVDV-2), and the respective titers of antibodies, were compared in 1,925 serum samples collected from unvaccinated and naturally infected cattle herds, located in the states of São Paulo and Minas Gerais, Brazil. The proportion of reagent samples among the genotypes was evaluated by McNemar test and the antibody titers against BVDV-1 and BVDV-2 were compared by Wilcoxon test. There were no disagreement in the proportion of BVDV-1 and BVDV-2 reagent samples (P>0.05). However, there was a disagreement among titers of antibodies detected in the VN tests against BVDV genotypes (P<0.0001). Although the proportion of reagent animals to BVDV genotypes was similar, false negative results would be obtained if 67 samples (3.5%) had been submitted only to VN test against BVDV-1, and 51 samples (2.65%) only against BVDV-2. Some herds had higher titers of antibodies for BVDV-1, while others for BVDV-2, thus demonstrating the occurrence of infection by different virus genotypes among the analyzed herds. Therefore, these results demonstrated the need for inclusion of both BVDV genotypes in VN tests.
