First detection and genetic characterization of bovine viral diarrhoea viruses (BVDV) types 1 and 2 in Tunisia

Two outbreaks associated with bovine viral diarrhoea infections (BVD) are reported in Tunisia. Their origin was determined by serological and virological studies. In farm A, out of 188 (58%) sera analyzed by an ELISA test, 164 were positive for BVD virus (BVDV) antibodies and 5 blood samples were positive by ELISA antigen and RT-PCR. Isolation of the virus on cell culture was successful in one animal. In farm B, out of 820 sera tested, 82% were positive for BVDV antibodies. Two BVDV isolates were recovered from blood of two persistently infected (PI) animals in cell culture. Genomic sequences of the 5'UTR and N-pro regions of BVDV responsible for these infections were compared to other sequences of pestivirus strains. Phylogenetic analysis showed that the two outbreaks were independent : analysis of sequences from farm A showed that they belonged to BVDV type 2, whereas isolates from the second outbreak belonged to BVDV type 1. This report demonstrates the presence of the two types of BVDV in Tunisia. The detection of BVDV1 and BVDV2 associated with severe losses in two farms strongly suggests a need to implement a control scheme for the surveillance of BVD in Tunisia.