Bovine viral diarrhoea (BVD) is an economically important cattle disease with a worldwide distribution. Detection and elimination of animals persistently infected (PI) with bovine viral diarrhoea virus (BVDV) is essential for the control of BVD and eradication of BVDV. Usually, there are no pathognomonic clinical signs of BVDV infection. Diagnostic investigations therefore rely on laboratory-based detection of the virus, or virus-induced antigens or antibodies. Erns as an immunogenic protein of BVDV is genetically and antigenically conserved among different isolates and therefore, a candidate antigen for developing ELISA for serological studies or identification of PI animals. In this study, a segment of BVDV genome corresponding to the sequence coding for Erns was amplified using RT-PCR and cloned into expression vector pMalc2x, under the control of the lac promoter. After sequencing of the gene, the recombinant protein was expressed in Escherichia coli BL-21 and analysed by SDS-PAGE and western blotting. The strong promoter of vector pMalc2x allowed a high level of Erns expression. Based on our results it appears that this plasmid construct may be suitable for the production of Erns recombinant antigen and Erns specific antibodies to develop BVDV laboratory diagnostic assays.
