Human parainfluenza virus induces a type-specific protective immune response.

Induction of type-specific and cross-protective immune responses against human parainfluenza viruses have been investigated. The envelope glycoproteins HN (76 kDa) and F0 (62 kDa) from parainfluenza type 2 virus were selectively solubilized with octylglucoside. Detergent-soluble envelope glycoproteins were used as vaccine antigens for intranasal immunization of hamsters. The immunized animals showed complete protection from challenge infection with prototype live virus but failed to demonstrate a significant level of protection against either human parainfluenza type 1 or type 3 virus. The sera and bronchial lavages of immunized animals also showed type-specific neutralizing antibodies. A similar type-specific protective immune response was also noted after primary infection with live virus. The results indicate that a multivalent parainfluenza virus vaccine is probably required for protection against natural infection.