The limitation of real-time PCR to span the entire diversity of HIV must be taken into account during treatment monitoring, resistance studies, and clinical trials.

No abstract

Semen represents the main vector for human immunodeficiency virus (HIV) dissemination worldwide and has been shown to harbor replication-competent virus despite otherwise effective highly active anti-retroviral therapy, which achieves undetectable viral load in plasma. Despite this, the origin of seminal HIV particles remains unclear, as does the question of whether the male genital tract organs contribute virus to semen. Here we investigated the presence of HIV receptors within the human testis using immunohistochemistry and quantitative real-time polymerase chain reaction. We also analyzed the infectivity of a dual tropic HIV-1 strain in an organotypic culture, as well as the impact of viral exposure on testosterone production. Our study establishes that CXCR4 ؉ , CCR5 ؉ , CD4 ؉ , and DC-SIGN With sexual contact being the main cause of the spread of human immunodeficiency virus (HIV) and male to female transmission rates being higher and more efficient than female to male, semen represents the foremost vector of HIV dissemination worldwide. However, the origin of the virus in the semen is still unclear. Several arguments point to the existence of local sources producing free viral particles in this bodily fluid. First, a number of studies clearly indicate that semen represents a viral compartment distinct from the blood.

Genotypic algorithms for prediction of HIV-1 coreceptor usage need to be evaluated in a clinical setting. We aimed at studying (i) the correlation of genotypic prediction of coreceptor use in comparison with a phenotypic assay and (ii) the relationship between genotypic prediction of coreceptor use at baseline and the virological response (VR) to a therapy including maraviroc (MVC). Antiretroviral-experienced patients were included in the MVC Expanded Access Program if they had an R5 screening result with Trofile (Monogram Biosciences). V3 loop sequences were determined at screening, and coreceptor use was predicted using 13 genotypic algorithms or combinations of algorithms. Genotypic predictions were compared to Trofile; dual or mixed (D/M) variants were considered as X4 variants. Both genotypic and phenotypic results were obtained for 189 patients at screening, with 54 isolates scored as X4 or D/M and 135 scored as R5 with Trofile. The highest sensitivity (59.3%) for detection of X4 was obtained with the Geno2pheno algorithm, with a false-positive rate set up at 10% (Geno2pheno10). In the 112 patients receiving MVC, a plasma viral RNA load of <50 copies/ml was obtained in 68% of cases at month 6. In multivariate analysis, the prediction of the X4 genotype at baseline with the Geno2pheno10 algorithm including baseline viral load and CD4 nadir was independently associated with a worse VR at months 1 and 3. The baseline weighted genotypic sensitivity score was associated with VR at month 6. There were strong arguments in favor of using genotypic coreceptor use assays for determining which patients would respond to CCR5 antagonist.During the entry process of HIV-1 in the target cell, the interaction of the viral surface glycoprotein gp120 with a cellular chemokine receptor, the coreceptor, is an essential step, besides attachment to the CD4 receptor, and precedes the fusion of the viral envelope to the cell membrane. The V3 hypervariable loop of gp120 is involved in coreceptor binding. Two coreceptors are most commonly used in vivo: CCR5 and CXCR4 (1). Viral coreceptor use (i.e., usage of either CCR5 or CXCR4) differs between viral isolates. If CCR5-using isolates (R5 isolates) are by far predominant at the early stage of early infection and seem to be selected during HIV-1 transmission, CXCR4 usage (X4 tropism) will become more prevalent as the infection progresses, with approximately half of X4 or dual or mixed (D/M) tropism in antiretroviral-experienced patients with advanced HIV-1 disease (10).Maraviroc (MVC), a CCR5 inhibitor, binds specifically to CCR5 and blocks HIV-1 binding to this coreceptor (5). MVC has shown a potent antiviral effect in antiretroviral-experienced patients with R5 HIV-1 infection in a placebo-controlled trial (7) and is currently prescribed in this indication. As MVC has shown little activity in patients with X4 viruses, the determination of HIV-1 coreceptor use has become mandatory before the prescription of CCR5 inhibitors (8).

We developed a new strategy for the analysis of correlation between genotype profile at baseline and virologic response.