Abstract:The identification of bovine viral diarrhea virus (BVDV) positive herds through detection of antibodies in milk may viabilize large scale control/eradication programs. With this objective, the virus neutralization test (VN) was adapted to detect BVDV antibodies in milk. The adaptation consisted of a reduction in the time of incubation followed by detection of viral antigens in the indicator cells by immunofluorescence (IFA) and allowed readings at 24 hours. The rapid virus neutralization test (RVN) was initial… Show more
“…BVD is distributed worldwide, and its seroprevalence is estimated to range between 46% and 78% (RICHTER et al, 2019). In Brazil, several serological studies have demonstrated a wide distribution and high prevalence rate in several states, as follows: Bahia, 56% (NoRoNHA et al, 2001); Paraíba, 39% (FERNANDES et al, 2016); Goiás, 54% (BRITo et al, 2010); Minas Gerais, 61% (MINEo et al, 2006); São Paulo, 56% (SAMARA et al, 2004); Paraná, 61% (AlFIERI et al, 2004); and Rio Grande do Sul, 58% (SCHERER et al, 2002). However, until now, no data were reported for the state of Espírito Santo.…”
This study evaluated the seroprevalence and associated factors of Infectious Bovine Rhinotracheitis (IBR) and Bovine Viral Diarrhea (BVD), and to analyze the possible relationship between IBR, BVD, and the occurrence of mastitis. For this purpose, 854 crossbred dairy cows were evaluated from 69 properties allocated in the 12 municipalities that make up the Caparaó region, Espírito Santo (ES), Brazil. The seroprevalence of IBR and BVD was determined using the indirect ELISA test. Associations between variables were estimated using the prevalence ratio (PR) with a 95% confidence interval. The chi-square test was used to verify the significance of the associations (P < 0.05). The average prevalence of IBR and BVD was 48.59% and 26.46%, respectively. Animals seroreactive for IBR were more likely to develop subclinical mastitis (P < 0.01; PR: 1.27), and cows that were seroreactive for BVD were more likely to develop clinical mastitis (P < 0.01; PR: 2.24). Mechanical milking was considered a factor associated with IBR (P < 0.01; PR: 1.36) and BVD (P < 0.01; PR: 1.25). Reproductive management by natural breeding was considered a factor associated with IBR (P < 0.01; PR: 1.22). Animals seroreactive for BVD were more likely to develop reproductive problems (P < 0.01; PR: 1.34). It was concluded that the agents that cause IBR and BVD are widely disseminated in dairy cattle herds in the municipalities of the Caparaó region, ES, Brazil. The presence of IBR and BVD increased the chances of cows developing subclinical mastitis and clinical mastitis, respectively, and the cows that were mechanically milked were more likely to be seroreactive for IBR and BVD.
“…BVD is distributed worldwide, and its seroprevalence is estimated to range between 46% and 78% (RICHTER et al, 2019). In Brazil, several serological studies have demonstrated a wide distribution and high prevalence rate in several states, as follows: Bahia, 56% (NoRoNHA et al, 2001); Paraíba, 39% (FERNANDES et al, 2016); Goiás, 54% (BRITo et al, 2010); Minas Gerais, 61% (MINEo et al, 2006); São Paulo, 56% (SAMARA et al, 2004); Paraná, 61% (AlFIERI et al, 2004); and Rio Grande do Sul, 58% (SCHERER et al, 2002). However, until now, no data were reported for the state of Espírito Santo.…”
This study evaluated the seroprevalence and associated factors of Infectious Bovine Rhinotracheitis (IBR) and Bovine Viral Diarrhea (BVD), and to analyze the possible relationship between IBR, BVD, and the occurrence of mastitis. For this purpose, 854 crossbred dairy cows were evaluated from 69 properties allocated in the 12 municipalities that make up the Caparaó region, Espírito Santo (ES), Brazil. The seroprevalence of IBR and BVD was determined using the indirect ELISA test. Associations between variables were estimated using the prevalence ratio (PR) with a 95% confidence interval. The chi-square test was used to verify the significance of the associations (P < 0.05). The average prevalence of IBR and BVD was 48.59% and 26.46%, respectively. Animals seroreactive for IBR were more likely to develop subclinical mastitis (P < 0.01; PR: 1.27), and cows that were seroreactive for BVD were more likely to develop clinical mastitis (P < 0.01; PR: 2.24). Mechanical milking was considered a factor associated with IBR (P < 0.01; PR: 1.36) and BVD (P < 0.01; PR: 1.25). Reproductive management by natural breeding was considered a factor associated with IBR (P < 0.01; PR: 1.22). Animals seroreactive for BVD were more likely to develop reproductive problems (P < 0.01; PR: 1.34). It was concluded that the agents that cause IBR and BVD are widely disseminated in dairy cattle herds in the municipalities of the Caparaó region, ES, Brazil. The presence of IBR and BVD increased the chances of cows developing subclinical mastitis and clinical mastitis, respectively, and the cows that were mechanically milked were more likely to be seroreactive for IBR and BVD.
A infecção pelo vírus da Diarréia V A infecção pelo vírus da Diarréia V A infecção pelo vírus da Diarréia V A infecção pelo vírus da Diarréia V A infecção pelo vírus da Diarréia Viral Bovina (BVDV) In addition to variable levels of positive serology in beef and dairy cattle, BVDV antibodies have been occasionally detected in swine, wild boars, goats, cervids and water buffaloes. BVDV infection has been diagnosed in aborted fetuses, buffy coats of persistently infected (PI) animals, clinical specimens from animals suffering from different clinical syndromes, semen of bulls of artificial insemination (AI) centers, in healthy fetuses and in commercial fetal bovine serum and/or cultured cells. About 50 isolates have been genetically and/or antigenically characterized up to date, whilst roughly an equivalent number of isolates awaits characterization. Most of the characterized isolates belong to BVDV-1 genotype, non-cytopathic (NCP) biotype, yet some BVDV-2 (and some CP BVDV) have been identified as well. Brazilian BVDV isolates display a high antigenic variability and are markedly different from North American vaccine strains. A few inactivated, polyvalent vaccines are currently licensed in the country, yet vaccination is still incipient in many regions: only about 2.5 million doses were marketed in 2003. The low serological cross-reactivity between vaccine strains and field isolates has recently stimulated national industries to develop vaccines containing Brazilian BVDV-1 and BVDV-2 strains. The overall knowledge about BVDV infection in Brazil has grown considerably in the last years, due to an increasing number of laboratories performing diagnosis and research. Studies on the pathogenesis, serological and molecular epidemiology and production of reagents for diagnosis have contributed decisively for the recent growing knowledge on BVDV infections in the country.
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.
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