A chimeric alphavirus RNA replicon gene-based vaccine for human parainfluenza virus type 3 induces protective immunity against intranasal virus challenge.

Parainfluenza virus type 3 (PIV3) infections continue to be a significant health risk for infants, young children, and immunocompromised adults. We describe a gene-based vaccine strategy against PIV3 using replication-defective alphavirus vectors. These RNA replicon vectors, delivered as virus-like particles and expressing the PIV3 hemagglutinin-neuraminidase glycoprotein, were shown to be highly immunogenic in mice and hamsters, inducing PIV3-specific neutralizing antibody responses. Importantly, the replicon particle-based vaccine administered intramuscularly or intranasally protected against mucosal PIV3 challenge in hamsters, preventing virus replication in both nasal turbinates and lungs. These data suggest that the alphavirus replicon platform can be useful for a PIV3 vaccine and possibly other respiratory viruses.