Bovine viral diarrhea virus subgenotype 1b in water buffalos (Bubalus bubalis) from Brazil.

Serological studies have characterized the presence of the bovine viral diarrhea virus (BVDV) infection in water buffalo herds worldwide. However, the molecular characterization of BVDV strains circulating in this animal species is uncommon. The aim of this study was to identify young water buffalo with acute infection and characterize the subgenotype of the infecting wild-type BVDV strain. Two dairy water buffalo herds from Northeastern Brazil were selected based on the results of virus neutralization test which showed high titers of anti-BVDV antibodies. To identify viremic animals, the BVDV RNA was assessed by RT-PCR assay in serum samples from 44 asymptomatic young water buffalos, where 31 serum samples from herd A and 13 from herd B. Amplicons with 288 bp of BVDV 5'UTR region were obtained in 7 (15.9%) serum samples (herd A, n = 5; herd B, n = 2). One good-quality amplicon from each herd was selected for nucleotide sequencing. The phylogenetic analysis demonstrated that the two BVDV wild-type strains clustered with BVDV strains of the subgenotype 1b. This study identified for the first time the active infection by BVDV subgenotype 1b in two dairy water buffalo herds from Brazil. These results highlight the importance of that, as well as in cattle herds, also in water buffalo herds prophylaxis measures to control BVDV infection should be intensified, mainly because these species clearly coexist in buffalo farms within Brazil.

Virus neutralization technique as a tool to evaluate the virological profile for bovine viral diarrhea virus infection in dairy water buffalo (Bubalus bubalis) herds.

Serological evidence shows that the bovine viral diarrhea virus (BVDV) infections are present in Brazilian dairy and beef water buffalo herds. As few reports describe the BVDV infection profile the aim of this study was to evaluate the dynamics of BVDV circulation in Brazilian dairy water buffalo herds through analysis of the seropositivity rate and the titer range of anti-BVDV neutralizing antibodies in a group of animals that are considered sentinels. Blood samples (n = 305) were obtained from unvaccinated, asymptomatic young water buffalos from four dairy herds randomly identified as A (n = 106), B (n = 62), C (n = 119), and D (n = 18). The detection and titration of anti-BVDV neutralizing antibodies were evaluated by the virus neutralization test according to the World Organization for Animal Health. Analysis of the results revealed two distinct epidemiological conditions. The first is represented by herds A and C where high rates of seropositive animals (A = 39.6%; C = 51.3%) and high and very variable antibodies titers suggested active BVDV infection. The other condition is represented by herds B and D with low rates of seropositive animals (B = 8.1%; D = 11.1%) and low and little variable antibodies titers suggesting an epidemiological condition of infection stability. Some variables were observed in herds with a distinct BVDV infection profile. Herds with active infection were big, open herds, and had more management practices. In contrast, the herds with infection stability were small, closed herds with few management practices. These results highlight the importance of evaluation, monitoring, and control of BVDV infection also in dairy water buffalo herds.