Human immunodeficiency virus type 1 (HIV-1) subtype C is the dominant subtype globally, due largely to the incidence of subtype C infections in sub-Saharan Africa and east Asia. We compared the relative replicative fitness (ex vivo) of the major (M) group of HIV-1 subtypes A, B, C, D, and CRF01_AE and group O isolates. To estimate pathogenic fitness, pairwise competitions were performed between CCR5-tropic (R5) or CXCR4-tropic (X4) virus isolates in peripheral blood mononuclear cells (PBMC). A general fitness order was observed among 33 HIV-1 isolates; subtype B and D HIV-1 isolates were slightly more fit than the subtype A and dramatically more fit than the 12 subtype C isolates. All group M isolates were more fit (ex vivo) than the group O isolates. To estimate ex vivo transmission fitness, a subset of primary HIV-1 isolates were examined in primary human explants from penile, cervical, and rectal tissues. Only R5 isolates and no X4 HIV-1 isolates could replicate in these tissues, whereas the spread to PM1 cells was dependent on active replication and passive virus transfer. In tissue competition experiments, subtype C isolates could compete with and, in some cases, even win over subtype A and D isolates. However, when the migratory cells from infected tissues were mixed with a susceptible cell line, the subtype C isolates were outcompeted by other subtypes, as observed in experiments with PBMC. These findings suggest that subtype C HIV-1 isolates might have equal transmission fitness but reduced pathogenic fitness relative to other group M HIV-1 isolates.

Objective Factors governing events between exposure of male genital mucosa surfaces and the establishment of infection are poorly understood. Furthermore, little is known about the safety and efficacy of microbicides on male genital mucosa. Design Here we present a novel penile tissue explant model to characterise the mechanisms of HIV-1 infection of male genital tissue and evaluate candidate microbicides. Methods Mucosal explant culture conditions were determined for glans, urethra and foreskin obtained from gender reassignment and circumcision. Density and distribution of CD4+ and CD1a+ cells were visualized by microscopy. In vitro HIV-1 infection was determined by measuring p24 release, while microbicide biocompatibility and efficacy were assessed by measurement of tissue viability, cytokine expression and p24 production. Results Cultured glans and foreskin showed comparable epithelial thickness but some differences in CD4+ and CD1a+ cell density. All tissue sites examined (foreskin, glans, meatus, urethra) were equally susceptible to R5 HIV-1 infection, which was productively disseminated by migratory cells emigrating from tissue. In contrast, X4 HIV-1 failed to infect mucosal tissue and dissemination by migratory cells was less efficient. The three candidate microbicides PMPA, PRO 2000 and Cyanovirin-N, showed good tissue compatibility and efficient prevention of HIV-1 infection, causing only minor changes in tissue cytokine profile. Conclusion The described model provides a useful model to study the determinants of HIV-1 infection of male genital tissue and is likely to be an important tool for the future development of microbicide candidates and concepts.

This study represents the first KC linkage replication study on the chromosomal region 5q21.2 and reports evidence of suggestive linkage in several regions for which suggestive or significant linkage has been previously detected in different populations.

A structurally novel candidate microbicide, PPCM, which is formed from the reaction of D,L-mandelic acid with sulfuric acid, provides activity against human immunodeficiency virus (HIV) and herpes simplex virus (HSV) and is not cytotoxic. The objectives of the current studies were to comprehensively evaluate the activity of PPCM in cell and explant cultures, explore the possibility of combining PPCM with HIV-specific reverse transcriptase inhibitors, and evaluate the efficacy of a formulated gel against genital herpes in a murine model. PPCM inhibited infection by laboratory and clinical R5 and X4 clade B and clade C HIV strains in cell culture. Ectocervical and endocervical tissue explants exposed to HIV-1 BaL in the presence of PPCM were protected (50% inhibitory concentrations [IC 50 ] of 3.9 g/ml for ectocervix and 3.1 g/ml for endocervix), and transfer of virus to target T cells via migratory cells was significantly impaired (IC 50 of 35.7 g/ml for ectocervix and 54.6 g/ml for endocervix). The drug also blocked infection by cell-associated virus. Combinations of PPCM with UC-781 or PMPA in vitro exhibited additive anti-HIV activity. PPCM was incorporated into stable, low-pH gel formulations at concentrations of 0.4% and 4%. Both gels prevented genital herpesvirus infection in mice, even when virus was introduced in human seminal plasma. The abilities of PPCM to inhibit primary HIV isolates, reduce infection by cell-associated virus, and transfer of HIV from migratory to T cells, combined with the complete protection provided by formulated gel against genital herpes, indicate that this drug is an excellent candidate for inclusion in a combination microbicide and would provide protection against both HIV and HSV.

In the present study we investigate the impact of a range of TLR ligands and chitosan as potential adjuvants for different routes of mucosal immunisation (sublingual (SL), intranasal (IN), intravaginal (IVag) and a parenteral route (subcutaneous (SC)) in the murine model. We assess their ability to enhance antibody responses to HIV-1 CN54gp140 (gp140) and Tetanus toxoid (TT) in systemic and vaginal compartments. A number of trends were observed by route of administration. For non-adjuvanted antigen, SC>SL>IN immunisation with respect to systemic IgG responses, where endpoint titres were greater for TT than for gp140. In general, co-administration with adjuvants increased specific IgG responses where IN = SC>SL, while in the vaginal compartment IN>SL>SC for specific IgA. In contrast, for systemic and mucosal IgA responses to antigen alone SL>IN = SC. A number of adjuvants increased specific systemic IgA responses where in general IN>SL>SC immunisation, while for mucosal responses IN = SL>SC. In contrast, direct intravaginal immunisation failed to induce any detectable systemic or mucosal responses to gp140 even in the presence of adjuvant. However, significant systemic IgG responses to TT were induced by intravaginal immunisation with or without adjuvant, and detectable mucosal responses IgG and IgA were observed when TT was administered with FSL-1 or Poly I∶C. Interestingly some TLRs displayed differential activity dependent upon the route of administration. MPLA (TLR4) suppressed systemic responses to SL immunisation while enhancing responses to IN or SC immunisation. CpG B enhanced SL and IN responses, while having little or no impact on SC immunisation. These data demonstrate important route, antigen and adjuvant effects that need to be considered in the design of mucosal vaccine strategies.