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The identification of transmission clusters (TCs) of HIV-1 using phylogenetic analyses can provide insights into viral transmission network and help improve prevention strategies. We compared the use of partial HIV-1 envelope fragment of 1,070 bp with its loop 3 (108 bp) to determine its utility in inferring HIV-1 transmission clustering. Serum samples of recently (n = 106) and chronically (n = 156) HIV-1-infected patients with status confirmed were sequenced. HIV-1 envelope nucleotide-based phylogenetic analyses were used to infer HIV-1 TCs. Those were constructed using ClusterPickerGUI_1.2.3 considering a pairwise genetic distance of ≤10% threshold. Logistic regression analyses were used to examine the relationship between the demographic factors that were likely associated with HIV-1 clustering. Ninety-eight distinct consensus envelope sequences were subjected to phylogenetic analyses. Using a partial envelope fragment sequence, 42 sequences were grouped into 15 distinct small TCs while the V3 loop reproduces 10 clusters. The agreement between the partial envelope and the V3 loop fragments was significantly moderate with a Cohen's kappa (κ) coefficient of 0.59, p

There is uncertainty regarding the potential virologic outcome associated with a change in antiretroviral therapy (ARV) among PLHIV who had previous documented virologic failure or who have been exposure to mono/dual nucleoside reverse transcriptase inhibitors (NRTI) therapy. The objective was to measure the potential impact of exposure to previous virologic failure or mono/dual NRTI regimen on virologic outcome of PLHIV following a switch to dolutegravir with 2 NRTIs from a viremia suppressive ARV therapy. Data from the Quebec HIV Cohort including 10219 PLHIV were collected through routine clinical care at 4 clinical sites in Montreal, Canada. This study includes patients whose ARV therapy was switched to dolutegravir with 2 NRTIs since 2013 with undetectable viral load for ≥6 months before switch. The association between exposure and post-switch virologic outcome was measured by marginal hazard ratio estimated using the Inverse probability weighting Cox model. Among the 1199 eligible PLHIV, 478 (39.9%) previously experienced at least one virologic failure or were exposed to mono/dual therapy before dolutegravir switch. Post-switch virologic failure after 30 months occurred in 4.1% (95% CI 2.1–7.9) of exposed compared to 4.1% (95% CI 2.3–7.4) in unexposed participants. The adjusted hazard ratio for the association between exposure and post-switch virologic failure was 0.84 (95% CI 0.35–2.01). Our findings suggest that switch to dolutegravir with 2 NRTIs from a suppressive therapy is a safe option for PLHIV with documented virologic failure and/or previous exposure to mono/dual NRTI therapy.

Background Switching antiretroviral regimens when human immunodeficiency virus (HIV) viremia is controlled for a new regimen is challenging when there is the potential for prior nucleoside reverse-transcriptase inhibitor (NRTI) resistance. The objective was to study virologic outcomes after switching to dolutegravir compared with remaining on a boosted protease inhibitor (protease inhibitor/ritonavir [PI/r]) regimen in people with HIV (PWH) with prior documented virologic failure and/or exposure to mono/dual NRTIs. Methods We used the Quebec HIV Cohort including 10 219 PWH whose data were collected at 4 sites in Montreal, Canada. We included all PWH with documented virologic failure or exposure to mono/dual NRTI therapy who were virologically suppressed on a PI/r-based regimen for at least 6 months on or after January 1, 2014 (n = 532). A marginal structural Cox model analysis was used to estimate the effect of the switch to dolutegravir on virologic outcome compared with remaining on PI/r. The outcome was defined as 2 consecutive viral loads (VLs) >50 copies/mL or 1 VL >50 copies/mL if it occurred at the last VL available. Results Among 532 eligible participants, 216 (40.6%) had their regimen switched to dolutegravir with 2 NRTIs, whereas 316 (59.4%) remained on the PI/r with 2 NRTIs. The weighted hazard ratio for the effect of dolutegravir switch on virologic failure compared with patients whose regimen remained on PI/r was 0.57 (95% confidence interval, 0.21–1.52). Conclusions We did not find evidence of an increased risk for virologic failure after switching to dolutegravir from PI/r among patients with previous virologic failure or prior exposure to mono/dual NRTI., Therapeutic switches to dolutegravir with 2 NRTIs provide a safe option for patients with a viremia suppressive antiretroviral regimen in the presence of prior documented virologic failure and prior exposure to mono/dual NRTI therapy.