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Year 2011 - Volume 31, Number 11
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ELISA and virus- neutralization in the detection of antibodies against bovine viral diarrhea virus in Milk, 31(11):985-990
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ABSTRACT.- Sturza D.A.F., Anziliero D., Weiblen R. & Flores E.F. 2011. [ELISA and virus- neutralization in the detection of antibodies against bovine viral diarrhea virus in Milk.] Testes de ELISA e vírus-neutralização na detecção de anticorpos contra o vírus da diarréia viral bovina no leite. Pesquisa Veterinária Brasileira 31(11):985-990. Setor de Virologia, Prédio 20, sala 4200, Departamento de Microbiologia e Parasitologia e Medicina Veterinária Preventiva, Universidade Federal de Santa Maria, Av. Roraima 1000, Camobi, Santa Maria, RS 97105-900, Brazil. E-mail: eduardofurtadoflores@gmail.com
The success of control/eradication programs of bovine viral diarrhea virus (BVDV) infection necessarily includes the identification and elimination of persistently infected (PI) animals. Since these animals continuously shed virus in secretions and excretions, the prevalence of antibodies in herds with PI animals is often high, and with high titers. Because of these characteristics, bulk milk samples were subjected to two serological techniques in order to establish the most appropriate in conducting screening of herds. For this, 767 bulk milk samples were analyzed by a indirect ELISA kit (reference test) and by an adapted virus neutralization (VNT) assay (proposed test). The toxic effects of milk on cell culture were reduced by increasing the final volume. One hundred seventy seven and 139 samples were positive in ELISA and VNT, respectively. Thus, the adapted VNT had a sensitivity of 76.8% and a specificity of 99.5%. The Kappa index (k) was 0.82, demonstrating an excellent agreement between the two techniques. The analysis of the coefficient of correlation between the absorbance values (OD) and VNT titers demonstrated a moderate positivity (r = 0.57). However, a significant part of samples with VNT titers ≥ 80 did not show high OD values. On the other hand, some samples with low VNT titers presented high ODs. VNT titers ≥ 80 are suggestive of the presence of PI animals in the herd. Therefore we conclude that the adapted VNT is more appropriate for herd screening when searching for herds with high antibody titers. |
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