Testes de ELISA e vírus-neutralização na detecção de anticorpos contra o vírus da diarréia viral bovina no leite

Abstract

Pesq. The success of control/eradication programs of bovine viral diarrhea virus (BVDV) infection necessarily includes the identiϐication 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 ϐinal 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 speciϐicity of 99.5%. The Kappa index (k) was 0.82, demonstrating an excellent agreement between the two techniques. The analysis of the coefϐicient of correlation between the absorbance values (OD) and VNT titers demonstrated a moderate positivity (r = 0.57). However, a signiϐicant 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.INDEX TERMS: Animals persistently infected, BVDV, diagnostic.

Sensitivity and specificity of indirect ELISA for the detection of antibody titers against BVDV from beef cattle raised in Pará State

“…Furthermore, 101 of the 400 samples (25.25%) had an antibody titer ≥80 on VN (Table 4). This can be because of the presence of animals in the acute phase of the disease and/or persistently infected animals (PIs), (STURZA et al, 2011) since herds that have PIs can be identified using serology, as the presence of the virus results in high levels of antibodies in most animals (HOUE, 1999). It is also worth noting that iELISA presented a positive result for all samples with an antibody titer ≥80 on VN.…”

Bovine Viral Diarrhoea Virus (BVDV) in Dairy Cattle: A Matched Case-Control Study

“…Many studies have estimated dairy and beef herd prevalence around the world (Paton et al., ; Ståhl et al., ; Thobokwe et al., ; Brülisauer et al., ), and it is well known that BVDV is also spread within Brazilian herds (Canal et al., ; Chaves et al., ). However, most studies previously conducted in Brazil used non‐probabilistic samples, and many have introduced bias into the prevalence and odds estimation (Dias and Samara, ; Flores et al., ; Chaves et al., ; Sturza et al., ).…”