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.