Prevention of sexually transmitted HIV infection was investigated in macaques by immunization with a recombinant SIV (simian immunodeficiency virus) envelope gp 120 and core p27 vaccine. In two independent series of experiments, we used the novel targeted iliac lymph node (TILN) route of immunization, aiming close to the iliac lymph nodes draining the genitorectal mucosa. Rectal challenge with the SIVmac 32H J5 molecular clone in two series induced total protection in four out of seven macaques immunized by TILN, compared with infection in 13 of 14 unimmunized macaques or immunized by other routes (P = 0.025). The remaining three macaques showed either a decrease in viral load ( > 90%) or transient viremia, indicating that all seven TILN-immunized macaques showed total or partial protection (P = 0.001). Protection was associated with significant increase in the iliac lymph nodes of IgA antibody-secreting cells to p27 (P < 0.02), CD8-suppressor factor (P < 0.01), and the chemokines RANTES and MIP-1 beta (P < 0.01).

We assessed the potential for an allogeneic-based vaccine against HIV infection in women who were allo-immunized with their partners' mononuclear leucocytes to prevent spontaneous recurrent abortion. Within 1 month of allo-immunization, there was significant upregulation in the concentrations of CD8 cell-derived suppressor factor activity, RANTES, and macrophage inflammatory proteins 1alpha and 1beta. Allo-immunization also downregulated the proportion of cells with CCR5 and CXCR4 receptors. We also found a dose-dependent decrease in HIV infectivity of CD4+ cells in vitro after allo-immunization with both primary and T-cell line adapted HIV-1. This study provides a rational basis for an alternative or complementary strategy of allo-immunization against HIV infection.

In view of the role of γ δ+ T cells in mucosal protection against infection, the proportion of γ δ T cells was examined in cells eluted from lymphoid and mucosal tissues of macaques immunized with simian immunodeficiency virus (SIV) gp120 and p27 in alum and challenged with live SIV by the rectal mucosal route. This revealed a significant increase in γ δ T cells eluted from the rectal mucosa (p < 0.01) and the related iliac lymph nodes (p < 0.0001) in protected as compared with infected macaques. Preferential homing of PKH‐26‐labeled γ δ+ T cells from the primed iliac lymph nodes to the rectal and cervico‐vaginal mucosa was demonstrated after targeted iliac lymph node as compared with i. m. immunization. Investigations of the mechanism of protection revealed that γ δ+ T cells can generate antiviral factors, RANTES, macrophage inflammatory protein (MIP)‐1α and MIP‐1β which can prevent SIV infection by binding to the CCR5 coreceptors. Up‐regulation of γ δ+ T cells was demonstrated by immunization of macaques with heat shock protein (HSP)70 linked to peptides and with granulocyte‐macrophage colony‐stimulating factor (GM‐CSF). This was confirmed by in vitro studies showing that GM‐CSF can up‐regulate γ δ+ T cells from macaques immunized with HSP‐linked peptides but not those from naive animals. We suggest that a novel strategy of immunization with HSP70 linked to antigen may generate both cognate immunity to the antigen and innate immunity by virtue of up‐regulation of γ δ+ T cells. These cells generate antiviral factors and the three β‐chemokines that prevent binding and transmission of SIV or M‐tropic HIV by the CCR5 coreceptor.