EXPRESSION OF RECOMBINANT US9 PROTEIN OF BOVINE HERPESVIRUS TYPE1.1 (BOHV-1.1) IN INSECT CELL LINE AND EXAMINE ITS APPLICATION IN AN IMMUNO ASSAY FOR THE DIAGNOSIS OF BOHV-1.1 INFECTED CATTLE

In this study, a recombinant baculovirus expressing the US9 tegument protein of the Egyptian BoHV-1.1 Abu-Hammad strain (vAc-Us9) was constructed using Bac-to-Bac expression system. A coding fragment of 435bp of Us9 gene was cloned into pFastBac-1 expression vector then transferred into the baculovirus expression vector system (BEVs) for expression f BoHV-1 US9 tegument protein. The PCR analysis of the recombinant virus confirmed the successful transposition of the expression cassette into the recombinant bacmid. The expressed US9 protein in infected cell culture was assayed using Indirect Immunofluorescence Assay (IFA) in addition to SDS-PAGE and western blot using crude cell lysate. The US9 protein expressed in infected cell culture supernatant as well as cell lysate were used as a coating antigen in an indirect enzyme linked immunosorbent assay (ELISA) to examine its sensitivity for the detection of the specific antibodies that generated against BoHV-1. The effectiveness of using of the expressed US9 protein as antigen for anti-US9 detection in serum samples infected with BoHV-1 was discussed in details.