HUMAN PARAINFLUENZA VIRUS TYPE-1 IMMUNIZATION OF INFANT MICE PROTECTSFROM SUBSEQUENT SENDAI VIRUS-INFECTION

Human parainfluenza virus type 1 (hPIV-1) infections are a common caus e of ''croup'' and hospitalizations among young children, yet no vacci ne is yet available. Sendai virus (mouse PIV-1) is the closest known h omologue of hPIV-1. Here we address the possibility of using a xenotro pic, nonpathogenic PIV as a vaccine in infants, by assessing the effic acy of hPIV-1 vaccination of infant mice against a subsequent challeng e with Sendai virus. hPIV-1 was administered intranasally to mice age 3-6 days and shown by serum antibody ELISA and elispot analysis to eli cit virus-specific IgM and isotype-switched antibody-forming cells (AF C). The response was completely cross-reactive between hPIV-1 and Send ai virus. Mice were challenged with Sendai virus 6-8 weeks later and g enerated AFC and serum antibody responses composed of IgM, as well as IgG and IgA, unlike challenged, age-matched controls. The high IgM res ponse among AFC was not seen in mice primed as adults with hPIV-1 and challenged with Sendai virus. The hPIV-1 priming of infant mice afford ed protection, as the majority of these mice survived the lethal Senda i virus challenge, as did all adult primed animals. These data support the notion that the unmodified xenotropic Sendai virus might function effectively in human infants as a vaccine against hPIV-1. (C) 1995 Ac ademic Press, Inc.