Human immunodeficiency virus type 1 Gag-specific vaginal immunity and protection after local immunizations with sindbis virus-based replicon particles.

The majority of human immunodeficiency virus (HIV) infections occur through vaginal and rectal transmission. In seeking a safe, nonreplicating gene-delivery vector that can induce mucosal and systemic immune responses and protection, Sindbis virus-based replicon particles expressing HIV-1 Gag (SIN-Gag) were developed. In mice, after nasal or intramuscular immunization with SIN-Gag and vaginal challenge with vaccinia virus (VV) expressing HIV-1 Gag (VV-Gag), CD8(+) T cell-mediated responses were detected locally, in the vaginal mucosa and in the draining iliac lymph nodes (ILNs), and systemically, in the spleen. However, the mice were not protected against VV-Gag replication in the ovaries. In contrast, after vaginal or rectal immunization with SIN-Gag and vaginal challenge with VV-Gag, despite lower local CD8(+) T cell-mediated responses in the vaginal mucosa and ILNs, the mice were protected against VV-Gag replication in the ovaries. Therefore, local immunization with SIN-Gag induced both local mucosal cell-mediated responses and protection.

Genetically detoxified mutants of heat-labile enterotoxin from Escherichia coli are effective adjuvants for induction of cytotoxic T-cell responses against HIV-1 gag-p55.

There is an urgent need for prophylactic and therapeutic vaccines against human immunodeficiency virus (HIV). Mucosal immunization strategies have great potential to elicit both mucosal and systemic cellular immunity required to protect against HIV-induced acquired immune deficiency syndrome (AIDS). However, mucosal immunizations with soluble protein antigens generally require adjuvants. In this study, we tested two mutants of the heat-labile enterotoxin (LT) from Escherichia coli, LTK63: with no measurable ADP-ribosyltransferase activity, and LTR72: with residual ADP-ribosyltransferase activity, as mucosal adjuvants for induction of cytotoxic T lymphocyte (CTL) responses to coadministered HIV gag p55 protein. We found that intranasal (i.n.) immunizations with HIV gag p55 protein coadministered with LTK63 or LTR72 induced systemic CTL responses comparable to that obtained following intramuscular (i. m.) immunizations with the same adjuvants. Moreover, oral coadministration of LTR72, but not LTK63, resulted in local as well as systemic p55-specific CTL responses in mesenteric lymph nodes (MLN) and spleens (SP) of the immunized mice. These data have important implications for current efforts to develop a safe vaccine against HIV.

Novel anionic microparticles are a potent adjuvant for the induction of cytotoxic T lymphocytes against recombinant p55 gag from HIV-1.

Microparticles with entrapped antigens have recently been shown to possess significant potential as vaccine delivery systems and adjuvants. However, the potential of microparticles as adjuvants has been seriously limited by the common problem of degradation and denaturation of antigens following encapsulation and release. To overcome these problems, we have developed a novel way to use microparticles as adjuvants, by the adsorption of proteins onto their surface. Anionic microparticles were prepared through the inclusion of an anionic detergent, sodium dodecyl sulphate (SDS), in the microparticle preparation process. The anionic microparticles were capable of the efficient and reproducible adsorption of recombinant p55 gag protein from HIV-1. Microparticles with adsorbed p55 were capable of inducing potent cytotoxic T lymphocyte responses in mice following intramuscular immunization. In addition, the microparticles also exhibited a potent adjuvant effect for antibody induction against p55.