S100B and AIDS: To determine whether the MVA A40R gene might have an immunomodulatory role that, in turn, could influence the immunogenicity profile of antigens delivered from a poxvirus vector, we deleted the MVA A40R gene from the HIV/AIDS vaccine candidate MVA-B (expressing HIV-1 Env, Gag, Pol, and Nef antigens from clade B) [16], generating the MVA-B deletion mutant termed MVA-B ΔA40R (see Materials and Methods) (Figure 1A).