Development of a Western blot assay for detection of bovine immunodeficiency-like virus using capsid and transmembrane envelope proteins expressed from recombinant baculovirus

A 120-amino-acid polypeptide selected from the transmembrane protein region (tTM) and the major capsid protein p26 of bovine immunodeficiency-like vir us (BIV) a ere expressed as fusion proteins from recombinant baculoviruses. The antigenic reactivity of both recombinant fusion proteins was confirmed by Western blot with bovine and rabbit antisera to BTV. BTV-negative bovin e sera and animal sera positive for bovine syncytial virus and bovine leuke mia virus failed to recognize the recombinant fusion proteins, thereby show ing the specificity of the BIV Western blot. One hundred and five bovine se rum samples were tested for the presence of anti-BLV antibodies by the reco mbinant protein-based Western blot and a reference Western blot assay using cell culture-derived virions as test antigens. There was a 100% concordanc e when the p26 fusion protein was used in the Western blot. However, the We stern blot using the tTM fusion protein as its test antigen identified four BN-positive bovine sera which had tested negative in both the p26 recombin ant-protein-based and the reference Western blot assays. This resulted in t he low er concordance of 96.2%, between the tTM-protein-based and reference Western blot assays. The results of this study showed that the recombinant p26 and tTM proteins can be used as test antigens for the serodetection of BTV-infection in animals.