A LIVE ATTENUATED BOVINE PARAINFLUENZA VIRUS TYPE-3 VACCINE IS SAFE, INFECTIOUS, IMMUNOGENIC, AND PHENOTYPICALLY STABLE IN INFANTS AND CHILDREN

The safety, infectivity, immunogenicity, transmissibility, and phenoty pic stability of an intranasal bovine parainfluenza virus type 3 (BPIV -3) candidate vaccine was evaluated in a randomized, double-blind, pla cebo-controlled trial. Of human parainfluenza virus type 3 (HPIV-3)-se ronegative children, 92% were infected, and 92% developed a serum hema gglutination-inhibiting (HAI) antibody response to BPIV-3 and 61% to H PIV-3. Geometric mean HAI titers were 1:40 to BPIV-3 and 1:16 to HPIV- 3. In studies to evaluate vaccine transmissibility, none of 14 placebo recipients in close contact with 14 vaccinees shed BPIV-3. BPIV-3 iso lates from seronegative vaccinees retained the attenuation phenotype w hen tested in rhesus monkeys. Although it is difficult to evaluate the safety and immunogenicity of such a vaccine in an open population of children who frequently become infected with HPIV-3, it appears that t he live BPIV-3 vaccine is attenuated, infectious, immunogenic, poorly transmissible, and phenotypically stable and warrants further evaluati on as a candidate vaccine in infants and children.