The epidemiology of bovine viral diarrhea virus infection on a dairy farm - clinical signs, seroprevalence, virus detection and genotyping

Abstract

In this study we investigated the presence of Bovine Viral Diarrhoea Virus (BVDV) antibodies and antigens in a dairy cow herd that had reported clinical signs related to BVDV infection. The aim of the study was to confirm BVDV infection on the dairy farm with 1500 Holstein-Friesian cattles, and genetically analyse the BVDV type/s circulating in the herd. Serum samples (n=233) were collected from clinically infected cattles and tested for the presence of BVDV antibodies and antigens. The virus neutralization test showed that 194 out of 233 sera of the tested cows were positive (83.26%), and by Ab-ELISA 203 sera samples of the tested cows were shown to be positive (87.12%). The presence of antigens was proven with the Ag-ELISA test in 2 out of 233 samples (0.86%). After RT-PCR and phylogenetic analysis of two BVD virus isolates, it was found that both isolates belonged to genotype 1, subtype BVDV-1d. This is the first time that the BVDV-1d subtype has been confirmed in Croatia, although the BVDV-1b and BVDV-1f subtypes have been detected previously on Croatian dairy farms.