Antigenic differences between the two major groups of respiratory syncytial (RS) virus may contribute to reinfections with these viruses. Additional variability occurs within the two major groups; the importance of intra-group variability in reinfections with RS virus has not been defined. Two pairs of group A viruses that had caused sequential infections in children showed G protein amino acid differences of up to 15%. Vaccinia viruses were constructed that expressed the G proteins from 2 of the paired group A isolates. Immunization of cotton rats with the recombinant vaccinia viruses provided equal protection against intranasal challenge by either of the RS viruses. Despite the amino acid differences between the two group A RS virus G proteins, these animal studies did not reveal differences in protection after immunization with the two G proteins. Precise definition of the role of RS virus antigenic variability in the establishment of reinfections in humans will require further investigations in humans.

Author notes

Presented in part: American Society for Virology, Ithaca, New York, July 1992, and Vancouver, British Columbia, July 1998; 32nd Interscience Conference on Antimicrobial Agents and Chemotherapy, Anaheim, California, October, 1992; and Society for Pediatric Research, New Orleans, May 1998.
Public Health Service and institutional guidelines were followed in animal experiments.
Financial support: NIH (AI-33425 to W.M.S., AI-20181 to G.W.W.). Support for nucleotide sequence analysis was provided by the Center for AIDS Research (AI-27767) and the X-Ray Crystallography Core Facility (CA-13148) at UAB. Support for the synthesis of oligonucleotides was provided though the UAB Comprehensive Cancer Center (CA-13148).