Identification of Potential B Cell Epitope Determinants by Computer Techniques,in Hemagglutinin–Neuraminidase from the Porcine Rubulavirus La Piedad Michoacan

Hemagglutinin–neuraminidase (HN) from porcine rubulavirus La Piedad Michoacan (RvpLPM) is one of the most antigenic proteins known, and is responsible for virus–host cell interaction. We analyzed the amino acid sequence of HN, using computer-assisted techniques to identify B cell epitopes. From a pool of 18 possible antigenic peptides, we evaluated the antigenicity of the 2 peptides with the highest scores and the 1 with lowest score. Antibodies from RvpLPM-infected pigs recognized the synthesized HN-A, HN-B, and HN-R peptides (optical density [OD]: 0.33 ± 0.02 for HN-A, 0.20 ± 0.02 for HN-B, and 0.07 ± 0.01 for HN-R); bovine serum albumin-coupled HN-A and HN-B induced rabbit anti-RvpLPM antibodies (OD: 0.39 ± 0.01 for HN-A and 0.35 ± 0.02 for HN-B). Loop 5 from the outer membrane protein, OmpC, from Salmonella typhi was replaced with HN-B; this protein was then expressed in Escherichia coli UH302. BALB/c mice were challenged intraperitoneally or orogastrically with the fusion protein expressed in E. coli and murine antibodies obtained from both types of administration inhibited virus-hemagglutinating activity, as did the antibodies from RvpLPM-infected swine. These results suggest that HN-A and HN-B are peptides involved in RvpLPM cell carbohydrate recognition, and could therefore be considered potential targets for vaccine and diagnostic procedures development.