SAFETY AND IMMUNOGENICITY OF THE PFP VACCINE AGAINST RESPIRATORY SYNCYTIAL VIRUS (RSV) - THE WESTERN-BLOT ASSAY AIDS IN DISTINGUISHING IMMUNE-RESPONSES OF THE PFP VACCINE FROM RSV INFECTION

PFP-1 vaccine was evaluated in a randomized controlled study in 47 RSV seropositive children. Trivalent inactivated influenza virus (TIV) va ccine was the control. Vaccine reactions were monitored and bloods wer e obtained before vaccination, 4 weeks after vaccination, and at the e nd of the RSV season. Respiratory illnesses were evaluated during the outbreak. Neutralizing antibody (Nt Ab) assay to RSV, IgG ELISA to RSV proteins and a Western blot assay were performed. Acute reactions wit h the PFP vaccine were mild. An early RSV outbreak resulted in infecti on of 44.4% of the TIV recipients shortly after vaccination, In the PF P vaccine groups, the Nt Ab and ELISA assays did not distinguish betwe en Ab rises due to natural infection versus vaccine; however, the West ern blot assay characterized the post-vaccine vises. Two major Western blot profiles were produced: an infection profile (antibodies that re cognized the F and G surface glycoproteins and internal proteins) and a vaccine profile (antibodies that recognized only the surface glycopr oteins). The PFP vaccinees who were not infected with RSV developed EL ISA and Nt Ab responses to the surface glycoproteins that were similar to the TIV vaccinees with natural RSV infection. None of the children developed vaccine-enhanced disease. Thus, the PFP-1 vaccine was safe and immunogenic in RSV seropositive children even when vaccine was adm inistered during a RSV outbreak, and the Western blot assay was useful in distinguishing Ab rises caused by RSV infection versus PFP vaccine .