Phylogenetic analysis of the Belgian HIV-1 epidemic reveals that local transmission is almost exclusively driven by men having sex with men despite presence of large African migrant communities.

To improve insight in the drivers of local HIV-1 transmission in Belgium, phylogenetic, demographic, epidemiological and laboratory data from patients newly diagnosed between 2013 and 2015 were combined and analyzed. Characteristics of clustered patients, paired patients and patients on isolated branches in the phylogenetic tree were compared. The results revealed an overall high level of clustering despite the short time frame of sampling, with 47.6% of all patients having at least one close genetic counterpart and 36.6% belonging to a cluster of 3 or more individuals. Compared to patients on isolated branches, patients in clusters more frequently reported being infected in Belgium (95.1% vs. 47.6%; p < 0.001), were more frequently men having sex with men (MSM) (77.9% vs. 42.8%; p < 0.001), of Belgian origin (68.2% vs. 32.9%; p < 0.001), male gender (92.6% vs. 65.8%; p < 0.001), infected with subtype B or F (87.8% vs. 43.4%; p < 0.001) and diagnosed early after infection (55.4% vs. 29.0%; p < 0.001). Strikingly, Sub-Saharan Africans (SSA), overall representing 27.1% of the population were significantly less frequently found in clusters than on individual branches (6.0% vs. 41.8%; p < 0.001). Of the SSA that participated in clustered transmission, 66.7% were MSM and this contrasts sharply with the overall 12.0% of SSA reporting MSM. Transmission clusters with SSA were more frequently non-B clusters than transmission clusters without SSA (44.4% versus 18.2%). MSM-driven clusters with patients of mixed origin may account, at least in part, for the increasing spread of non-B subtypes to the native MSM population, a cross-over that has been particularly successful for subtype F and CRF02_AG. The main conclusions from this study are that clustered transmission in Belgium remains almost exclusively MSM-driven with very limited contribution of SSA. There were no indications for local ongoing clustered transmission of HIV-1 among SSA.

Performance evaluation of the two protease sequencing primers of the Trugene HIV-1 genotyping kit.

This article describes the performance of the two protease sequencing modules available in the Trugene HIV-1 genotyping Kit on a sample population with a high prevalence of HIV-1 non-B subtypes (n=110). The relevance of the algorithm recommended by the kit was also evaluated. The results indicated a high sequencing failure rate of the PR module (34%). Forty-five percent of the failed sequences derived from non-B subtype viruses. Furthermore, no PR sequence could be obtained from any of the HIV-1 subtype A and C infected samples that were tested. In contrast, a sequence could be obtained from the entire panel using the P2 module. The data indicated that the high rate of sequencing failures of the PR module was related to both the HIV-1 non-B subtypes as well as lower levels of RNA viral load. In six out of the 73 samples for which both protease modules were successful, discrepancies between the two protease sequences were observed, which led to discordant resistance reports in two cases. The data highlight the problems and the clinical implications that may occur during resistance genotyping of clinical samples with a high prevalence of HIV-1 non-B subtypes.

Performance of a quantitative human immunodeficiency virus type 1 p24 antigen assay on various HIV-1 subtypes for the follow-up of human immunodeficiency type 1 seropositive individuals.

The heat-denatured signal-amplified p24 antigen assay is a low-cost test allowing the determination of plasma levels of HIV-1 p24 antigen in infected patients. This assay may be appropriate for monitoring disease progression in HIV seropositive patients in developing countries. Only a few data on the clinical validation of the test are available for HIV-1 non-subtypes B viruses that represent the vast majority of virus circulating in Africa. The present study was undertaken to evaluate and compare the performance of a heat-denatured signal-amplified p24 assay for the determination of p24 viral load in the plasma of individuals infected with different subtypes of HIV-1 and using the RT-PCR-based RNA viral load test as the gold standard. A total of 120 plasma samples from individuals infected with HIV-1 strains belonging to group M (subtypes A-->H) and group O, as well as recombinant strains, were tested in parallel with the heat-denatured signal-amplified p24 assay and the RNA viral load. Plasma p24 levels appeared to be correlated significantly with the plasma RNA viral loads (R=0.751, P<0.0001). The heat-denatured p24 antigen assay was capable of measuring the plasma level of p24 derived from all the HIV-1 subtypes and recombinants selected for this study, in contrast to the RNA viral load test which lacked sensitivity towards HIV-1 group O. The heat-denatured signal-amplified p24 assay is a reliable, sensitive and a more affordable tool that can be used for the follow-up of patients infected with B and non-B subtypes as well as recombinant forms of HIV-1 in developing countries.