IFNA1 and AIDS: To determine whether immunomodulatory VACV genes blocking the IFN signaling pathway at the intracellular level (such as C6L and K7R) could affect the immunogenicity profile against HIV-1, we have constructed a single and a double MVA-B deletion mutant lacking VACV genes C6L and/or K7R (viruses termed MVA-B ΔC6L and MVA-B ΔC6L/K7R; see Materials and Methods) from the HIV/AIDS vaccine candidate MVA-B (expressing HIV-1 Env, Gag, Pol and Nef antigens from clade B) [16].