Objective: To evaluate the safety and immunogenicity of PIV3 subunit vaccine in children.

Vaccine: Copurified PIV3 Hemagglutonin-neuraminidase(HN) and fusion(F) glycoproteins 25 mcg; Control vaccine: EngerixR-B 20 mcg; Placebo control: Alum adjuvant.

Method: Randomized, double-blind controlled trial. Subjects: 39 healthy children age 24-36 mos. Table

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Measures: Safety assessment; humeral immune response with neutralizing antibody(NA), hemagglutination inhibition(HI), and enzyme linked immunoassay(EIA) to HN & F; and cellular immune response with lymphocyte proliferation to PIV3 and cytokines IFN and IL10. Children were monitored for acute respiratory infections including virus isolation during the full 9 mo follow-up. Results: There were no apparent local or systemic clinical adverse events. A significant increase in GMT (p<0.05) was noted 1 mo after immunization for HI, EIA, and NA. By 7 months after immunization, all GMTs had returned to pre-immunization levels. Vaccine induced lymphocyte proliferation for PIV3 was not demonstrated.

Conclusion: A PIV3 subunit vaccine containing HN & F glycoproteins was well tolerated, and safe in this population. An initial immunogenic antibody response was demonstrated to single dose of vaccine. Further work is continuing to elucidate the cytokine profile of responders and nonresponders. Funded by Pasteur Merieux Connaught Canada