Antigenicity and immunogenicity of the V3 domain of HIV type 1 glycoprotein 120 expressed on the surface of Streptococcus gordonii.

Five different V3 domains of HIV-1 gp120 were expressed on the surface of the gram-positive bacterium Streptococcus gordonii, a model live vector for vaccine delivery. Sera of HIV-1-infected individuals and human monoclonal antibodies specifically recognized the gp120 sequences on the bacterial surface. Recombinant V3 from the reference HIV-1 strain MN was also shown to retain a conformation that allowed reaction with a conformation-specific monoclonal antibody. A V3-specific serum antibody response was detected in mice immunized both by subcutaneous injection and by vaginal colonization. V3-specific IgG2a antibodies, suggestive of a Th1 response, were found in the sera of mice colonized by recombinant bacteria.