Journal of virology 2017 02 08() pii 10.1128/JVI.02182-16
The non-replicating attenuated poxvirus vector NYVAC expressing clade C(CN54) HIV-1 Env(gp120), Gag-Pol-Nef antigens (NYVAC-C) showed in phase I clinical trials limited immunogenicity. To enhance the capacity of the NYVAC vector to trigger broad humoral responses and a more balanced activation of CD4(+) and CD8(+) T cells, here we compared the HIV-1-specific immunogenicity elicited in non-human primates immunized with two replicating NYVAC vectors that have been modified by the insertion of K1L and C7L vaccinia viral host-range genes and express clade C(ZM96) trimeric HIV-1 gp140 protein or a Gag(ZM96)-Pol-Nef(CN54) polyprotein as Gag-derived virus-like particles (termed NYVAC-C-KC). Additionally, one NYVAC-C-KC vector was generated by deleting the viral gene B19R, an inhibitor of type I interferon response (NYVAC-C-KC-ΔB19R). An immunization protocol mimicking the RV144 phase III clinical trial was used. Two groups of macaques received two doses of the corresponding NYVAC-C-KC vectors (weeks 0 and 4), and booster doses with NYVAC-C-KC vectors plus clade C HIV-1 gp120 protein (weeks 12 and 24). The two replicating NYVAC-C-KC vectors induced an enhanced and similar HIV-1-specific CD4(+) and CD8(+) T cell responses, similar levels of binding IgG antibodies, low levels of IgA antibodies, high levels of antibody-dependent cellular cytotoxicity responses and HIV-1-neutralizing antibodies. Small differences within the NYVAC-C-KC-ΔB19R group were seen in the magnitude of CD4(+) and CD8(+) T cells, induction of some cytokines and in the neutralization of some HIV-1 isolates. Thus, replication-competent NYVAC-C-KC vectors acquired relevant immunological properties as vaccine candidates against HIV/AIDS, and the viral B19 molecule exerts some control of immune functions.IMPORTANCE It is of special importance to find a safe and effective HIV/AIDS vaccine that can induce strong and broad T cell and humoral immune responses correlating with HIV-1 protection. Here we developed novel replicating poxvirus NYVAC-based HIV/AIDS vaccine candidates expressing clade C HIV-1 antigens, with one of them lacking the vaccinia B19 protein, an inhibitor of type I interferon response. Immunization of non-human primates with these novel NYVAC-C-KC vectors and the protein component gp120 elicited a high level of T cell and humoral immune responses, with the vector containing the deletion in B19R inducing a trend to higher magnitude of CD4(+) and CD8(+) T cells and neutralization of some HIV-1 strains. These poxvirus vectors could be considered as HIV/AIDS vaccine candidates based on their activation of potential immune correlates of protection.