Induction of human immunodeficiency virus type 1-specific T cells by a bluetongue virus tubule-vectored vaccine prime-recombinant modified virus Ankara boost regimen

In the absence of strategies for reliable induction of antibodies broadly neutralizing human immunodeficiency virus type 1 (HIV-1), vaccine efforts have shifted toward the induction of cell-mediated immunity. Here we describe the construction and immunogenicity of novel T-cell vaccine NS1.HIVA, which delivers the HIV-1 clade A consensus-derived immunogen HIVA on the surface of tubular structures spontaneously formed by protein NS1 of bluetongue virus. We demonstrated that NS1 tubules can accommodate a protein as large as 527 amino acids without losing their self-assembly capability. When injected into BALB/c mice by several routes, chimeric NS1.HIVA tubules induced HIV-1-specific major histocompatibility complex class I-restricted T cells. These could be boosted by modified virus Ankara expressing the same immunogen and generate a memory capable of gamma interferon (IFN-gamma) production, proliferation, and lysis of sensitized target cells. Induced memory T cells readily produced IFN-gamma 230 days postimmunization, and upon a surrogate virus challenge, NS1.HIVA vaccine alone decreased the vaccinia virus vv.HIVA load in ovaries by 2 orders of magnitude 280 days after immunization. Thus, because of its T-cell immunogenicity and antigenic simplicity, the NS1 delivery system could serve as a priming agent for heterologous prime-boost vaccination regimens. Its usefulness in primates, including humans, remains to be determined.