Serum neutralizing antibody titers of seropositive chimpanzees immunized with vaccines coformulated with natural fusion and attachment proteins of respiratory syncytial virus

Subunit vaccines formulated with purified fusion proteins from the A2 (PFP- 2) or attenuated 248/404 (PFP-3) strains of respiratory syncytial virus (RS V) were evaluated, either alone or in combination with native attachment (G ) protein, for their ability to augment serum neutralizing antibody titers in seropositive chimpanzees. The results suggested that combination vaccine s enhanced serum neutralizing antibody titers against both laboratory strai ns and clinical isolates of RSV, When compared with PFP-2 alone, the result ant neutralizing antibody titers after vaccination with PFP-2+Ga protein we re significantly elevated against 71% of A strains tested. In a confirmator y experiment, immunization with PFP-3+Ga+Gb proteins resulted in elevated s erum neutralizing antibody titers against 86% of A and 50% of B strains tes ted versus injection with PFP-3 alone. The results suggest that subunit vac cines composed of both PFP and G proteins have more potential than PFP alon e to augment neutralizing antibody titers in seropositive recipients.