These findings suggest that HIV-1 replicative fitness may have decreased in the human population since the start of the pandemic. This 'attenuation' could be the consequence of serial bottlenecks during transmission and result in adaptation of HIV-1 to the human host.

BackgroundDuring HIV infection and/or antiretroviral therapy (ART), monocytes and macrophages exhibit a wide range of dysfunctions which contribute significantly to HIV pathogenesis and therapy-associated complications. Nevertheless, the molecular components which contribute to these dysfunctions remain elusive. We therefore applied a parallel approach of genome-wide microarray analysis and focused gene expression profiling on monocytes from patients in different stages of HIV infection and/or ART to further characterise these dysfunctions.ResultsProcesses involved in apoptosis, cell cycle, lipid metabolism, proteasome function, protein trafficking and transcriptional regulation were identified as areas of monocyte dysfunction during HIV infection. Individual genes potentially contributing to these monocyte dysfunctions included several novel factors. One of these is the adipocytokine NAMPT/visfatin, which we show to be capable of inhibiting HIV at an early step in its life cycle. Roughly half of all genes identified were restored to control levels under ART, while the others represented a persistent dysregulation. Additionally, several candidate biomarkers (in particular CCL1 and CYP2C19) for the development of the abacavir hypersensitivity reaction were suggested.ConclusionsPreviously described areas of monocyte dysfunction during HIV infection were confirmed, and novel themes were identified. Furthermore, individual genes associated with these dysfunctions and with ART-associated disorders were pinpointed. These genes form a useful basis for further functional studies concerning the contribution of monocytes/macrophages to HIV pathogenesis. One such gene, NAMPT/visfatin, represents a possible novel restriction factor for HIV.

Background: CRF02_AG is the predominant HIV strain circulating in West and West Central Africa. The aim of this study was to test whether this predominance is associated with a higher in vitro replicative fitness relative to parental subtype A and G viruses. Primary HIV-1 isolates (10 CRF02_AG, 5 subtype A and 5 subtype G) were obtained from a well-described Cameroonian cohort. Growth competition experiments were carried out at equal multiplicity of infection in activated T cells and monocyte-derived dendritic cells (MO-DC) in parallel.

The use of microbicides is a promising approach for the prevention of HIV-1 transmission. Unfortunately, various candidates failed in clinical trials. In some cases, the candidate microbicide even resulted in enhanced virus transmission. Therefore, there is an urgent need to develop more predictive preclinical strategies to anticipate the in vivo efficiency/toxicity rate, including in vitro assays that evaluate effects on epithelial integrity and inflammation. The present study aims to identify potential safety issues concerning the use of microbicides and excipients commonly used in vaginal microbicide preparations. The toxicities of various active pharmaceutical ingredients (APIs; TMC-120, UC-781, tenofovir [PMPA], PRO-2000, and glycerol monolaurate [GML]) and excipients (preservatives, cosolvents, surfactants, and cyclodextrins) were evaluated using an in vitro dual-chamber model and uterine cervical explants. Epithelial viability and permeation of fluorescent virus-sized beads, as well as induction of interleukin-8 (IL-8; as a sensitive marker of an inflammatory response), were assessed. Surprisingly, cell viability and epithelial layer integrity were compromised by most excipients at concentrations near the typical concentration used in vaginal gels, and a significant increase in the production of IL-8 was observed at subtoxic concentrations. Within the APIs, TMC-120, UC-781, and PMPA showed higher selectivity indices than PRO-2000 and GML. In conclusion, identification of safety issues concerning the use of pharmaceutical excipients could help to formulate less toxic vaginal microbicide preparations.

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Changes in virulence and fitness during an epidemic are common among pathogens. Several studies have shown that HIV fitness increases within a patient during disease progression, while bottlenecks, such as sexual transmission, immune pressure and drug treatment can reduce fitness. In this study, we analyzed how these opposing forces have shaped HIV-1 fitness over time. Therefore, we compared the replicative fitness of HIV-1 isolates from newly infected untreated individuals, diagnosed for HIV-1 infection early in the AIDS epidemic in Amsterdam, the Netherlands, with more recent isolates. Twenty-five early and late HIV-1 isolates, carefully matched for seroconversion time, were competed head-to-head in a dual infection/competition assay, employing peripheral blood mononuclear cells. In contrast with previous studies, we observed a trend of increasing fitness over time in the HIV epidemic of Amsterdam. Apparently, the bottleneck, occurring with each transmission event, does not completely reset the fitness increase acquired during disease progression.

CCR5-tropic viruses cause the vast majority of new HIV-1 infections while about half of the individuals infected with HIV-1 manifest a co-receptor switch (CCR5 (R5) to CXCR4 (X4)) prior to accelerated disease progression. The underlying biological mechanisms of X4 outgrowth in AIDS patients are still poorly understood. Although X4 viruses have been associated with increased "virulence" in vivo, in vitro replication and cytopathicity studies of X4 and R5 viruses have led to conflicting conclusions. We studied the replicative fitness of HIV-1 biological clones with different co-receptor tropism, isolated from four AIDS patients. On average, R5 and X4 clones replicated equally well in mitogen-activated T cells. In contrast, X4 variants were transferred more efficiently from dendritic cells to autologous CD4+ T cells. These observations suggest that interaction between X4 viruses, DC and T cells might contribute to the preferential outgrowth of X4 viruses in AIDS patients.

BackgroundTwo HIV-1 positive patients, L and P, participating in the Amsterdam Cohort studies acquired an HIV-1 superinfection within half a year from their primary HIV-1 infection (Jurriaans et al., JAIDS 2008, 47:69-73). The aim of this study was to compare the replicative fitness of the primary and superinfecting HIV-1 strains of both patients. The use of isolate-specific primer sets indicated that the primary and secondary strains co-exist in plasma at all time points after the moment of superinfection.ResultsBiological HIV-1 clones were derived from peripheral blood CD4 + T cells at different time point, and identified as the primary or secondary virus through sequence analysis. Replication competition assays were performed with selected virus pairs in PHA/IL-2 activated peripheral blood mononuclear cells (PBMC's) and analyzed with the Heteroduplex Tracking Assay (HTA) and isolate-specific PCR amplification. In both cases, we found a replicative advantage of the secondary HIV-1 strain over the primary virus. Full-length HIV-1 genomes were sequenced to find possible explanations for the difference in replication capacity. Mutations that could negatively affect viral replication were identified in the primary infecting strains. In patient L, the primary strain has two insertions in the LTR promoter, combined with a mutation in the tat gene that has been associated with decreased replication capacity. The primary HIV-1 strain isolated from patient P has two mutations in the LTR that have been associated with a reduced replication rate. In a luciferase assay, only the LTR from the primary virus of patient P had lower transcriptional activity compared with the superinfecting virus.ConclusionsThese preliminary findings suggest the interesting scenario that superinfection occurs preferentially in patients infected with a relatively attenuated HIV-1 isolate.