Immunogenicity of recombinant envelope glycoproteins derived from T-cell line-adapted isolates or primary HIV isolates: a comparative study using multivalent vaccine approaches

We investigated immunogenic properties of native envelope glycoproteins derived from HIV-1 (subtype B). Our main objective was to assess whether the design of multivalent vaccines affects generation of neutralizing antibodies against primary viruses. Recombinant Semliki Forest virus (SFV) particles producing various HIV-1 envelope glycoproteins were used as vaccine vectors. The following multivalent vaccination approaches were compared: 1) immunization with a mixture of recombinant SFV expressing envelope glycoproteins derived from three HIV-1 primary isolates and two T-cell laboratory-adapted (TCLA) viruses; 2) immunization with a mixture of recombinant SFV expressing only the envelope glycoproteins derived from three HIV-1 primary isolates; 3) sequential immunizations with the recombinant SFV expressing the envelope glycoproteins derived from three HIV-1 primary isolates and two TCLA viruses, respectively. Two monovalent vaccine approaches using SFV expressing envelope glycoproteins derived from a single primary isolate or TCLA virus were also included in the study. The multivalent vaccination strategies based on SFV vaccine vectors did not induce more neutralizing antibodies than the previously tested TCLA envelope immunogens, which gave disappointing results against primary isolates.