[Cloning, expression and characterization of HIV-1 gp60 partially or completely deleted in the V3 loop]

In order to better understand the role of the immunodominant V3 loop in the type-specific immune response and also to determine if this sequence has a role in AIDS pathogenesis, notably in the induction of apoptosis in CD4+ cells, we have introduced 2 modifications in the env gene from pNL4-3: a partial deletion in the V3 loop, keeping only the conserved tip of the loop GPGRAF consensus sequence (env delta V3-GPGRAF) and, secondly, a complete deletion of V3 sequence plus 43 nucleotides in C3 (env delta V3+). These constructions as well as the non-modified env gene, were cloned and expressed in a baculovirus system. Western blot analysis has shown that both modified env gene products reacted with a reference anti-HIV-1 serum to the same extent as the non-modified gp 160. However, in contrast to the non-modified env-protein and to env delta V3-GPGRAF, the env delta V3+ protein failed to bind to CD4 molecule, although V3 is not directly involved in receptor binding. These modified and non-modified recombinant proteins will be very useful to determine the potential of the partially or totally V3-deleted gp 160 to induce broadly reactive neutralizing antibodies and also to determine if V3 has a role in certain aspects of HIV-induced pathogenesis, notably apoptosis.