Despite significant HIV inhibitory activity, cervicovaginal levels of alpha-defensins and LL-37 were associated with increased HIV acquisition, perhaps due to their association with bacterial sexually transmitted infections.

Using a unique proteomics approach in a large scale, cross-sectional cohort study, we identified elafin/trappin-2 as a novel innate immune factor, which is highly associated with resistance. This association was confirmed within an independent, prospective cohort study. Genital tract elafin/trappin-2 levels constitute a natural correlate of HIV protection in humans.

Genital HIV-neutralizing IgA and systemic HIV-specific proliferative responses, assayed by blinded investigators, were prospectively associated with HIV nonacquisition. The induction of these immune responses may be an important goal for HIV vaccines.

The foreskin is the main site of heterosexual HIV acquisition in uncircumcised men, but functional data regarding T cells subsets present at this site are lacking. Foreskin tissue and blood were obtained from Ugandan men undergoing elective adult circumcision. Tissue was treated by mechanical and enzymatic digestion followed by T cell subset identification and assessment of cytokine production using flow cytometery. Foreskin CD4+ T cells were predominantly an effector memory phenotype, and compared to blood they displayed a higher frequency of CCR5 expression (42.0% vs. 9.9%) and IL-17 production. There was no difference in T regulatory cell frequency, but IFNγ and TNFα production were increased in foreskin CD8+ T cells. These novel techniques demonstrate that the foreskin represents a pro-inflammatory milieu that is enriched for HIV-susceptible T cell subsets. Further characterization of foreskin T cell subsets may help to define the correlates of HIV susceptibility in the foreskin.

A biological explanation for the reduction in HIV-1 (HIV) acquisition after male circumcision may be that removal of the foreskin reduces the number of target cells for HIV. The expression of potential HIV target cells and C-type lectin receptors in foreskin tissue of men at risk of HIV infection were thus analyzed. Thirty-three foreskin tissue samples, stratified by Herpes simplex virus type 2 status, were obtained from a randomized, controlled trial conducted in Kenya. The samples were analyzed by confocal in situ imaging microscopy and mRNA quantification by quantitative RT-qPCR. The presence and location of T cells (CD3(+)CD4(+)), Langerhans cells (CD1a(+)Langerin/CD207(+)), macrophages (CD68(+) or CD14(+)), and submucosal dendritic cells (CD123(+)BDCA-2(+) or CD11c(+)DC-SIGN(+)) were defined. C-type lectin receptor expressing cells were detected in both the epithelium and submucosa, and distinct lymphoid aggregates densely populated with CD3(+)CD4(+) T cells were identified in the submucosa. Although the presence of lymphoid aggregates and mRNA expression of selected markers varied between study subjects, Herpes simplex virus type 2 serostatus was not the major determinant for the detected differences. The detection of abundant and superficially present potential HIV target cells and submucosal lymphoid aggregates in foreskin mucosa from a highly relevant HIV risk group demonstrate a possible anatomical explanation that may contribute to the protective effect of male circumcision on HIV transmission.

HIV susceptibility is heterogeneous, with some HIV-exposed but seronegative (HESN) individuals remaining uninfected despite repeated exposure. Previous studies in the cervix have shown that reduced HIV susceptibility may be mediated by immune alterations in the genital mucosa. However, immune correlates of HIV-exposure without infection have not been investigated in the foreskin. We collected sub-preputial swabs and foreskin tissue from HESN (n=20) and unexposed control (n=57) men undergoing elective circumcision. Swabs were assayed for HIV-neutralizing IgA, innate antimicrobial peptides, and cytokine levels. Functional T cell subsets from foreskin tissue were assessed by flow cytometry. HESN foreskins had elevated α-defensins (3027 vs. 1795 pg/ml, p=0.011) and HIV-neutralizing IgA (50.0 vs. 13.5% of men, p=0.019). Foreskin tissue from HESN men contained a higher density of CD3 T cells (151.9 vs. 69.9 cells/mm2, p=0.018), but a lower proportion of these were Th17 cells (6.12 vs. 8.04% of CD4 T cells, p=0.007), and fewer produced TNFα (34.3 vs. 41.8% of CD4 T cells, p=0.037; 36.9 vs. 45.7% of CD8 T cells, p=0.004). A decrease in the relative abundance of susceptible CD4 T cells and local TNFα production, in combination with HIV-neutralizing IgA and α-defensins, may represent a protective immune milieu at a site of HIV exposure.

A subgroup of women enrolled in the Pumwani sex worker cohort remain seronegative and PCR negative for human immunodeficiency virus type 1 despite repeated exposure through high-risk sex work. Studies have shown that polymorphisms of genes involved in antigen presentation and viral restriction factors are associated with resistance to HIV infection. To discover other possible genetic factors underlying this HIV-resistant phenotype, we conducted an exploratory nonbiased, low-resolution, genome-wide single-nucleotide polymorphism (SNP) analysis comparing 60 HIV-resistant women to 48 HIV-infected controls. The SNP minor allele rs1552896, in an intron of FREM1, was significantly associated with the resistant phenotype (P ‫؍‬ 1.68 ؋ 10 ؊5 ; adjusted P ‫؍‬ 2.37 ؋ 10 ؊4 ; odds ratio [OR], 9.51; 95% confidence interval [CI], 2.82 to 32.05). We expanded the sample size by genotyping rs1552896 in the Pumwani cohort and comparing 114 HIV-resistant women to 609 HIV-infected controls and confirmed the association (P ‫؍‬ 1.7 ؋ 10 ؊4 ; OR, 2.67; 95% CI, 1.47 to 4.84). To validate the association in a second cohort, we genotyped 783 women enrolled in a mother-child health study and observed the minor allele of rs1552896 enriched in HIV-uninfected women (n ‫؍‬ 488) compared to HIV-infected enrollees (n ‫؍‬ 295) (P ‫؍‬ 0.036; OR, 1.69; 95% CI, 0.98 to 2.93). Quantitative reverse transcription-PCR showed that FREM1 mRNA was highly expressed in tissues relevant for HIV-1 infection, and immunohistochemical analysis revealed that FREM1 protein is expressed in the ectocervical mucosa of HIV-resistant women. The significant association of rs1552896 with an HIV-resistant phenotype, together with the expression profile of FREM1 in tissues relevant to HIV infection, suggests that FREM1 is a potentially novel candidate gene for resistance to HIV infection.

Adverse pregnancy outcome due to human parvovirus B19 (hereafter referred to as "parvovirus B19") has been characterized, in numerous reports, as an event that occurs during the first and second trimesters and is strongly associated with symptoms of fetal hydrops. Recent findings have indicated that parvovirus B19-associated intrauterine fetal death (IUFD) is also a problem in late gestation, although its clinical presentation is aberrant, lacking signs of fetal hydrops. We outlined the clinical presentation and assessed the frequency of parvovirus B19 infection in a retrospective analysis of 92 unselected cases of IUFD that occurred during or after gestational week 22. By polymerase chain reaction, parvovirus B19 DNA was detected in 13 (14%) of the 92 cases. Only 2 of the parvovirus B19 DNA-positive cases were hydropic, both representing early IUFDs. This finding indicates that parvovirus B19-associated IUFD in late gestation is a common finding and that hydropic presentation is rare. This knowledge may contribute to a reduction in the number of unexplained cases of IUFD.