ENGINEERING, EXPRESSION AND CHARACTERIZAT ION OF HIV-1 GP160 PARTIALLY OR COMPLETELY DELETED IN THE V3 LOOP

In order to better understand the role of the immunodominant V3 loop i n the type-specific immune response and also to determine if this sequ ence has a role in AIDS pathogenesis, notably in the induction of apop tosis in CD4(+) cells, we have introduced 2 modifications in the env g ene from pNL4-3: a partial deletion in the V3 loop, keeping only the c onserved tip of the loop GPGRAF consensus sequence (env Delta V3-GPGRA F) and, secondly, a complete deletion of V3 sequence plus 43 nucleotid es in C3 (env Delta V3+). These constructions as well as the non-modif ied env gene, were cloned and expressed in a baculovirus system. Weste rn blot analysis has shown that both modified env gene products reacte d with a reference anti-HIV-1 serum to the same text as the non-modifi ed gp160. 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 m olecule, although V3 is not directly involved in receptor binding. The se modified and non-modified recombinant proteins will be very useful to determine the potential of the partially or totally V3-deleted gp16 0 to induce broadly reactive neutralizing antibodies and also to deter mine if V3 has a role in certain aspects of HIV-induced pathogenesis, notably apoptosis.