Glycoproteins of human parainfluenza virus type 3: characterization and evaluation as a subunit vaccine

The envelope glycoproteins of human parainfluenza type 3 virus were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reactivity with specific monoclonal antibodies. The molecular weight of the hemagglutinin-neuraminidase (HN) glycoprotein was found to be 72,000, and the fusion (F) glycoprotein appeared to consist of 74,000 (F0) or 56,000 (F1) species. Envelope glycoproteins were solubilized with octyl-glucoside and, after removal of the detergent by dialysis, were used for immunization of hamsters. Other animals were immunized with a formalin-inactivated preparation of whole virus. A single subcutaneous immunization with these antigen preparations induced a serum antibody response to the HN and F glycoproteins, as determined by plaque neutralization, hemagglutination inhibition, inhibition of virus-induced cell fusion, and immune precipitation tests. An IgG antibody response to both glycoproteins was also observed in bronchial washings. Animals immunized with the highest dose of envelope glycoproteins showed complete protection from challenge infection, whereas immunization with inactivated virus did not completely protect animals.