The ability of viral glycoproteins (VP) VP4/VP7 reassortant swine rotaviruses (RV) to induce cross-neutralizing antibody against parental serotypes was investigated in guinea pigs. Using selective culture conditions, we produced 10 reassortant viruses that contained gene segment 4 of the OSU RV strain and gene segment 9 of the Gottfried RV strain. These reassortant RV grew to high titer in cell culture and were neutralized by monospecific antisera against both parental RV strains. The reassortant RV were chemically inactivated with binary ethylenimine, adjuvanted with aluminum hydroxide, and used to produce antisera in guinea pigs. The hyperimmune antisera had high neutralization titer against both parent RV strains. These results indicate that several of the reassortant RV may be capable of inducing neutralizing antibodies to VP4 and VP7 and may have future use as bivalent vaccine strains.

Previously identified 39-, 50-, and 76-kd integral outer membrane proteins (IOMP) of Actinobacillus pleuropneumoniae, a respiratory tract pathogen, were separated by electroelution of sodium dodecyl sulfate-polyacrylamide gel electrophoresis-obtained fragments and their role in opsonophagocytosis by porcine leukocytes was investigated by flow cytometry of fluorescein-labeled A pleuropneumoniae. Using specific antisera, immunoblot analysis indicated that the 3 proteins were antigenically distinct. Antibodies against each IOMP have an important role as opsonins for phagocytosis by porcine leukocytes. The effect of using a combination of an 3 of the specific antisera was minimal. Antiserum absorbed against intact A pleuropneumoniae and Escherichia coli organisms indicated that the antibodies to the 39-, 50-, and 76-kd IOMP were specific for A pleuropneumoniae antigens. Nonheat-treated antiserum did not increase phagocytosis, compared with heat-inactivated antiserum, indicating that complement may not have a major role in opsonization of A pleuropneumoniae.