A Single-Dose Recombinant Parainfluenza Virus 5-Vectored Vaccine Expressing Respiratory Syncytial Virus (RSV) F or G Protein Protected Cotton Rats and African Green Monkeys from RSV Challenge.

Human respiratory syncytial virus (RSV) is a common cause of severe respiratory illness in infants, immunocompromised individuals, and the elderly. There is no licensed vaccine is currently available. In this study, we evaluated two Feline Recombinant Proteins parainfluenza virus 5 (PIV5) -vectored vaccine expressing RSV F (PIV5 / F) or G (PIV5 / G) protein in cotton rats and African green monkey models for their replication, immunogenicity, and efficacy of protection against RSV challenge.

After a single intranasal inoculation, both species of animals shedding virus vaccine for a limited time but without any clinical symptoms appear. In the cotton rat, causing RSV vaccine F- or G-specific serum antibodies and lung given complete protection against RSV challenge at doses as low as 103 PFU. The vaccine is not produced improved lung pathology was observed in animals immunized with a formalin-inactivated RSV. 

In African green monkeys, the vaccine-induced serum and mucosal antibody response that is easily detectable, as well. PIV5 / F provides nearly complete protection against RSV infection in the upper respiratory tract and lower at doses of 106 pfu vaccine. At the same dose level, PIV5 / G is less effective. Both PIV5 / F and PIV5 / G was also able to boost neutralizing titers in RSV-preexposed African green monkeys.

Overall, our data suggest that PIV5 / F is a promising RSV vaccine candidate.IMPORTANCE A safe and efficacious vaccine respiratory syncytial virus (RSV) remains elusive. We tested the recombinant parainfluenza virus 5 (PIV5) vectors expressing RSV glycoprotein on the immunogenicity and protective efficacy in mice cotton and African green monkeys, which are the best available animal model for the study of RSV infection.

 In both species, a single dose of intranasal Guinea Pig Recombinant Proteins immunization with PIV5 vaccine vectors capable of producing local and systemic immunity and to protect the animals from RSV challenge. Vaccines can also increase the RSV titer neutralizing antibodies in African green monkeys that had been infected previously. Our data indicate that the vaccine vectors PIV5 potentially protecting both children and the elderly population and support continued development of the vector platform.