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New South Wales has the greatest burden of HIV in Australia, with 2012 and 2013 recording the highest rates of new diagnoses in 20 years. Concurrently, there has been significant changes in antiretroviral treatments and testing paradigms. We compiled a statewide resistance database to characterize changes in HIV-1 resistance mutations over time. Genotypic antiretroviral resistance testing (GART) was performed on request at three reference laboratories using commercial and in-house methods. In total, 7629 HIV-1 polymerase sequences obtained from GART from 2004 to 2013 were retrospectively collated, reformatted, de-identified, and analyzed using Stanford HIVdb program 7.0 and the 2009 World Health Organization (WHO) surveillance drug resistance mutations (SDRMs). Analyses were performed on subgroups of known treatment naives, treatment experienced, and seroconverters. There has been a decrease in overall rates of prevalent drug resistance mutations from 57.8% in 2004 to 21% in 2013. Dual and triple class resistance mutations have decreased from 32.7% in 2004 to 5.8% in 2013 and 16.4% to 1.2%, respectively. In treatment-naive individuals ( n  = 450), the frequency of protease inhibitor (PI) mutations remains low at 2.7%. In seroconverters, rates of transmitted drug resistance (TDR) are 6.6%, 3%, 3%, and 1.5% for overall, PI, non-nucleoside reverse transcription inhibitor (NNRTI), and NRTI, respectively. In treatment experienced, rates remain stable with 36.0%, 18.9%, 29.1%, and 6.4% for overall, NNRTI, NRTI, and PI mutations. The most common mutations in treatment experienced occurred at position M184, T215 (NRTI); K103 (NNRTI); I54 (PI). Apparent decreases in prevalent SDRMs can be attributed to changes in GART testing indications over time. In treatment-naive and -experienced subgroups, rates have been stable with low rates of TDR in seroconverters.

Objective: Development of immunogens that elicit an anti-HIV-1 broadly neutralizing antibody (bnAb) response will be a key step in the development of an effective HIV-1 vaccine. Although HIV-1 bnAb epitopes have been identified and mechanisms of action studied, current HIV-1 envelope-based immunogens do not elicit HIV-1 bnAbs in humans or animal models. A better understanding of how HIV-1 bnAbs arise during infection and the clinical factors associated with bnAb development may be critical for HIV-1 immunogen design efforts., Design and Methods: Longitudinal plasma samples from the treatment-naive control arm of the Short Pulse Anti-Retroviral Therapy at Seroconversion (SPARTAC) primary HIV-1 infection cohort were used in an HIV-1 pseudotype neutralization assay to measure the neutralization breadth, potency and specificity of bnAb responses over time., Results: In the SPARTAC cohort, development of plasma neutralization breadth and potency correlates with duration of HIV infection and high viral loads, and typically takes 3-4 years to arise. bnAb activity was mostly directed to one or two bnAb epitopes per donor and more than 60% of donors with the highest plasma neutralization having bnAbs targeted towards glycan-dependent epitopes., Conclusion: This study highlights the SPARTAC cohort as an important resource for more in-depth analysis of bnAb developmental pathways., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc.)

Memory CD4+ T cells (mCD4s) containing integrated HIV DNA are considered the main barrier to a cure for HIV infection. Here, we analyzed HIV DNA reservoirs in antigen-specific subsets of mCDs to delineate the mechanisms by which HIV reservoirs persist during antiretroviral therapy (ART). HIV Gag, cytomegalovirus (CMV), and tetanus toxoid (TT)-specific mCD4s were isolated from peripheral blood samples obtained from 11 individual subjects, 2-11 years after commencing ART. Antigen-specific mCD4s were identified by the sensitive OX40 assay and purified by cell sorting. Total HIV DNA levels were quantified by real-time PCR, and clonal viral sequences generated from mCD4 subsets and pre-ART plasma samples. Quantitative results and sequence analysis were restricted to five and three study participants, respectively, which was likely due to the low frequency of the antigen-specific mCD4s and relatively low HIV DNA proviral loads. Median HIV Gag-, CMV-, and TT-specific mCD4s were 0.61%, 2.46%, and 0.78% of total mCD4s, and they contained a median of 2.50, 2.38, and 2.55 log 10 copies of HIV DNA per 10 6 cells, respectively. HIV DNA sequences were derived from antigen-specific mCD4s clustered with sequences derived from pre-ART plasma samples. There was a trend toward increased viral diversity in clonal viral sequences derived from CMV-specific mCD4s relative to TT-specific mCD4s. Despite limitations, this study provides direct evidence that HIV reservoirs persist in memory CD4+ T cell subsets maintained by homeostatic proliferation (TT) and adds to growing evidence against viral evolution during ART. Similar future studies require techniques that sample diverse HIV reservoirs and with improved sensitivity.

There is growing interest in utilizing antibody-dependent cellular cytotoxicity (ADCC) to eliminate infected cells following reactivation from HIV-1 latency. A potential barrier is that HIV-1-specific ADCC antibodies decline in patients on long-term antiretroviral therapy (ART) and may not be sufficient to eliminate reactivated latently infected cells. It is not known whether reactivation from latency with latency-reversing agents (LRAs) could provide sufficient antigenic stimulus to boost HIV-1-specific ADCC. We found that treatment with the LRA panobinostat or a short analytical treatment interruption (ATI), 21 to 59 days, was not sufficient to stimulate an increase in ADCC-competent antibodies, despite viral rebound in all subjects who underwent the short ATI. In contrast, a longer ATI, 2 to 12 months, among subjects enrolled in the Strategies for Management of Antiretroviral Therapy (SMART) trial robustly boosted HIV-1 gp120-specific Fc receptor-binding antibodies and ADCC against HIV-1-infected cells in vitro These results show that there is a lag between viral recrudescence and the boosting of ADCC antibodies, which has implications for strategies toward eliminating latently infected cells. IMPORTANCE The "shock and kill" HIV-1 cure strategy aims to reactivate HIV-1 expression in latently infected cells and subsequently eliminate the reactivated cells through immune-mediated killing. Several latency reversing agents (LRAs) have been examined in vivo , but LRAs alone have not been able to achieve HIV-1 remission and prevent viral rebound following analytical treatment interruption (ATI). In this study, we examined whether LRA treatment or ATI can provide sufficient antigenic stimulus to boost HIV-1-specific functional antibodies that can eliminate HIV-1-infected cells. Our study has implications for the antigenic stimulus required for antilatency strategies and/or therapeutic vaccines to boost functional antibodies and assist in eliminating the latent reservoir., (Copyright © 2017 American Society for Microbiology.)

Background: There is growing interest in immune therapies to clear the latent HIV-1 after combination antiretroviral therapy (cART). There is limited information on the effect of cART on antibody-dependent cellular cytotoxicity (ADCC), and no studies have directly compared ADCC in HIV-1 subtype B- and subtype C-infected subjects. The effect of improving immunocompetence on ADCC to influenza also remains unexplored., Methods: The effect of cART on HIV-1- and influenza-specific ADCC was analyzed in 2 cohorts (39 subtype B- and 47 subtype C-infected subjects) before and after 2 years of cART. ADCC analyses included an enzyme-linked immunosorbent assay-based dimeric recombinant soluble (rs) FcγRIIIa-binding assay, antibody-dependent natural killer cell activation assay, and ADCC-mediated killing assays., Results: HIV-1 subtype B and C Env-specific antibody binding to dimeric rsFcγRIIIa were reduced in subtypes B- and C-infected cohorts after 2 years of cART (both P < 0.05). Reduced ADCC-mediated killing of target cells expressing subtype B Env in the subtype B-infected cohort (P = 0.003) was observed after 96 weeks of cART, but not of subtype C Env in the subtype C-infected cohort. A greater reduction in ADCC was detected in subjects with baseline CD4 counts >300 cells/μL (P < 0.05). The resolving immunodeficiency after 96 weeks of cART resulted in improved HA-specific ADCC to 6 strains of influenza (all P < 0.01)., Conclusions: cART results in HIV-1 antigen loss and reductions in HIV-1 Env-specific antibodies with Fc functionality in both subtype B- and C-infected subjects, particularly in immunocompetent subjects. Simultaneously, cART improves ADCC to diverse strains of influenza, suggesting reduction in influenza disease after cART.

HIV-1 reservoirs are most often studied in peripheral blood (PB), but not all lymphocytes recirculate, particularly T follicular helper (Tfh) CD4 + T cells, as well as germinal center (GC) B cells, in lymph nodes (LNs). Ultrasound-guided fine needle biopsies (FNBs) from inguinal LNs and PB samples were obtained from 10 healthy controls (HCs) and 21 HIV-1-infected subjects [11 antiretroviral therapy (ART) naive and 10 on ART]. Tfh cells and GC B cells were enumerated by flow cytometry. HIV-1 DNA and cell-associated (CA) RNA levels in LNs and PB were quantified by real-time polymerase chain reaction. FNBs were obtained without adverse events. Tfh cells and GC B cells were highly elevated in ART-naive subjects, with a median GC B cell count >300-fold higher than HCs, but also remained higher in 4 out of the 10 subjects on ART. GC B cell counts and Tfh cell counts were highly correlated with each other, and also with activated T cells in LNs but not in blood. Levels of HIV-1 DNA and CA RNA viral burden in highly purified CD4 + T cells from FNBs were significantly elevated compared with those in CD4 + T cells from PB in the ART-naive group, but only trended toward an increase in the ART patients. FNBs enabled minimally invasive access to, and parallel measurement of residual activated T and B cells and viral burden within LNs in HIV-1-infected patients. These FNBs revealed significant GC activity that was not apparent from corresponding PB samples.

We investigate mutations and correlates according to HIV-1 subtype after virological failure (VF) of standard first-line antiretroviral therapy (ART) (non-nucleoside/nucleotide reverse transcriptase inhibitor [NNRTI] +2 nucleoside/nucleotide reverse transcriptase inhibitor [N(t)RTI]). SECOND-LINE study participants were assessed at baseline for HIV-1 subtype, demographics, HIV-1 history, ART exposure, viral load (VL), CD4(+) count, and genotypic ART resistance. We used backward stepwise multivariate regression (MVR) to assess associations between baseline variables and presence of ≥3 N(t)RTI mutations, ≥1 NNRTI mutation, ≥3 thymidine analog-N(t)RTI [ta-N(t)RTI] mutations (TAMs), the K65/K70 mutation, and predicted etravirine (ETV)/rilpivirine (RPV) activity. The inclusion p-value for MVR was p < .2. The exclusion p-value from stepwise elimination was p > .05. Of 541 participants, 491 (91%) had successfully characterized baseline viral isolates. Subtype distribution: B (n = 123, 25%), C (n = 202, 41%), CRF01&#95;AE (n = 109, 22%), G (n = 25, 5%), and CRF02&#95;AG (n = 27, 5%). Baseline CD4(+) 200-394 cells/mm(3) were associated with <3 N(t)RTI mutations (OR = 0.47; 95% CI 0.29-0.77; p = .003), absence of the K65/K70 mutation (OR = 0.43; 95% CI 0.26-0.73; p = .002), and higher ETV sensitivity (OR = 0.52; 95% CI 0.35-0.78; p = .002). Recent tenofovir (TDF) use was associated with K65/K70 mutations (OR = 8.91; 95% CI 5.00-15.85; p < .001). Subtype CRF01&#95;AE was associated with ≥3 N(t)RTI mutations (OR = 2.34; 95% CI 1.31-4.17; p = .004) and higher RPV resistance (OR = 2.13; 95% CI 1.30-3.49; p = .003), and subtype C was associated with <3 TAMs (OR = 0.45; 95% CI 0.21-0.99; p = .015). Subtypes CRF01&#95;AE (OR = 2.46; 95% CI 1.26-4.78; p = .008) and G (OR = 4.77; 95% CI 1.44-15.76; p = .01) were associated with K65/K70 mutations. Higher VL at confirmed first-line VF was associated with ≥3 N(t)RTI mutations (OR = 1.39; 95% CI 1.07-1.78; p = .013) and ≥3 TAMs (OR = 1.62; 95% CI 1.15-2.29; p = .006). The associations of first-line resistance mutations across the HIV-1 subtypes in this study are consistent with knowledge derived from subtype B, with some exceptions. Patterns of resistance after failure of a first-line ta-N(t)RTI regimen support using TDF in N(t)RTI-containing second-line regimens, or using N(t)RTI-sparing regimens.

Competing Interests: The authors have declared that no competing interests exist.

Ritonavir-boosted tipranavir (TPV/r) was evaluated as initial therapy in treatment-naïve HIV-1-infected patients because of its potency, unique resistance profile, and high genetic barrier. Trial 1182.33, an open-label, randomized trial, compared two TPV/r dose combinations versus ritonavir-boosted lopinavir (LPV/r). Eligible adults, who had no prior antiretroviral therapy were randomized to twice daily (BID) 500/100 mg TPV/r, 500/200 mg TPV/r, or 400/100 mg LPV/r. Each treatment group also received Tenofovir 300 mg + Lamivudine 300 mg QD. The primary endpoint was a confirmed viral load (VL) <50 copies/mL at week 48 without prior antiretroviral regimen changes. Primary analyses examined CD4-adjusted response rates for non-inferiority, using a 15% non-inferiority margin. At week 48, VL<50 copies/mL was 68.4%, 69.9%, and 72.4% in TPV/r100, TPV/r200, and LPV/r groups, respectively, and TPV/r groups showed non-inferiority to LPV/r. Discontinuation due to adverse events was higher in TPV/r100 (10.3%) and TPV/r200 (15.3%) recipients versus LPV/r (3.2%) recipients. The frequency of grade ≥3 transaminase elevations was higher in the TPV/r200 group than the other groups, leading to closure of this group. However, upon continued treatment or following re-introduction after treatment interruption, transaminase elevations returned to grade ≤2 in >65% of patients receiving either TPV/r200 or TPV/r100. The trial was subsequently discontinued; primary objectives were achieved and continuing TPV/r100 was less tolerable than standard of care for initial highly active antiretroviral therapy. All treatment groups had similar 48-week treatment responses. TPV/r100 and TPV/r200 regimens resulted in sustained treatment responses, which were non-inferior to LPV/r at 48 weeks. When compared with the LPV/r regimen and examined in the light of more current regimens, these TPV/r regimens do not appear to be the best options for treatment-naïve patients based on their safety profiles.

Treatment of HIV-1 infection with antiretroviral therapy (ART) in the weeks following transmission may induce a state of 'post-treatment control' (PTC) in some patients, in whom viraemia remains undetectable when ART is stopped. Explaining PTC could help our understanding of the processes that maintain viral persistence. Here we show that immunological biomarkers can predict time to viral rebound after stopping ART by analysing data from a randomized study of primary HIV-1 infection incorporating a treatment interruption (TI) after 48 weeks of ART (the SPARTAC trial). T-cell exhaustion markers PD-1, Tim-3 and Lag-3 measured prior to ART strongly predict time to the return of viraemia. These data indicate that T-cell exhaustion markers may identify those latently infected cells with a higher proclivity to viral transcription. Our results may open new avenues for understanding the mechanisms underlying PTC, and eventually HIV-1 eradication.

Objective: Interruption of antiretroviral therapy (ART) in chronic HIV disease is associated with increased mortality, predicted by elevations in interleukin-6 (IL-6) and D-dimer. The effect of ART interruption in primary HIV-1 infection on these biomarkers is unknown., Methods: Plasma samples from 200 HIV seroconverters enrolled in the Short Pulse Anti-Retroviral Therapy At HIV Seroconversion trial of deferred ART (standard of care) - 12 or 48 week ART (ART12 or ART48, respectively) - were analysed for IL-6 and D-dimer at weeks 0, 12, 16, 48, 52, 60 and 108 after randomization. Changes in log10 levels from weeks 0 to 12 were analysed using linear regression, as were changes from baseline to 4 weeks after stopping ART. Areas under the biomarker-time curves (AUC) to week 108 were adjusted for baseline values, and compared across all arms., Results: Median (inter-quartile range) baseline IL-6 and D-dimer were 1.45 (0.88, 2.41) pg/ml and 0.34 (0.20, 0.50) mg/l, respectively. At week 12, D-dimer levels were significantly lower among treated compared to untreated individuals (P < 0.001), whereas IL-6 levels were similar (P = 0.23). Within 4 weeks from stopping ART, IL-6 and D-dimer levels rose by 22 and 18%, reaching pre-ART levels. Over 108-week follow-up, there was no difference between arms in IL-6 AUC (P = 0.53), but D-dimer AUC was significantly lower for ART12 and ART48 compared to standard of care (overall P = 0.008)., Conclusion: Stopping ART in primary HIV-1 infection leads to inflammatory biomarker rebound to pre-treatment levels. However, over 108-week follow-up, we found no evidence that biomarker levels were higher for those interrupting ART, compared to those remaining ART-naïve, and D-dimer levels were significantly lower.

Background: The week 48 primary analysis of the ENCORE1 trial established the virological non-inferiority and safety of efavirenz 400 mg compared with the standard 600 mg dose, combined with tenofovir and emtricitabine, as first-line HIV therapy. This 96-week follow-up of the trial assesses the durability of efficacy and safety of this treatment over 96 weeks., Methods: ENCORE1 was a double-blind, placebo-controlled, non-inferiority trial done at 38 clinical sites in 13 countries. HIV-infected adult patients (≥16 years of age) with no previous antiretroviral therapy, a CD4 cell count of 50-500 cells per μL, and plasma HIV-1 viral load of at least 1000 copies per mL were randomly assigned (1:1) by an electronic case report form to receive fixed-dose daily tenofovir 300 mg and emtricitabine 200 mg plus efavirenz either 400 mg daily or 600 mg daily. Participants, physicians, and all other trial staff were masked to treatment assignment. Randomisation was stratified by HIV-1 viral load at baseline (≤ or >100 000 copies per mL). The primary endpoint was the difference in the proportions of patients in the two treatment groups with a plasma HIV-1 viral load below 200 copies per mL at week 96. Treatment groups were deemed to be non-inferior if the lower limit of the 95% CI for the difference in viral load was above -10% by modified intention-to-treat analysis. Non-inferiority was assessed in the modified intention-to-treat, per-protocol, and non-completer=failure (NC=F) populations. Adverse events and serious adverse events were summarised by treatment group. This study is registered with ClinicalTrials.gov, number NCT01011413., Findings: Between Aug 24, 2011, and March 19, 2012, 636 eligible participants were enrolled and randomly assigned to the two treatment groups (324 to efavirenz 400 mg and 312 to efavirenz 600 mg). The intention-to-treat population who received at least one dose of study drug comprised 630 patients: 321 in the efavirenz 400 mg group and 309 in the efavirenz 600 mg group. 585 patients (93%; 299 in the efavirenz 400 mg group and 286 in the 600 mg group) completed 96 weeks of follow-up. At 96 weeks, 289 (90·0%) of 321 patients in the efavirenz 400 mg group and 280 (90·6%) of 309 in the efavirenz 600 mg group had a plasma HIV-1 viral load less than 200 copies per mL (difference -0·6, 95% CI -5·2 to 4·0; p=0·72), which suggests continued non-inferiority of the lower efavirenz dose. Non-inferiority was recorded for thresholds of less than 50 and less than 400 copies per mL, irrespective of baseline plasma viral load. Adverse events were reported by 291 (91%) of 321 patients in the efavirenz 400 mg group and by 285 (92%) of 309 in the 600 mg group (p=0·48). The proportions of patients reporting an adverse event that was definitely or probably related to efavirenz were 126 (39%) for efavirenz 400 mg and 148 (48%) for efavirenz 600 mg (p=0·03). The number of patients who reported serious adverse events did not differ between the groups (p=0·20)., Interpretation: Our findings confirm that efavirenz 400 mg is non-inferior to the standard dose of 600 mg in combination with tenofovir and emtricitabine as initial HIV therapy over 96 weeks. Fewer efavirenz-related adverse events were reported with the 400 mg efavirenz dose than with the 600 mg dose. These findings support the routine use of efavirenz 400 mg. The coadministration of rifampicin and efavirenz 400 mg needs further investigation., Funding: Bill & Melinda Gates Foundation, and UNSW Australia., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: WHO-recommended second-line antiretroviral therapy (ART) of a pharmacologically enhanced (boosted) protease inhibitor plus nucleoside or nucleotide reverse transcriptase inhibitors (NtRTIs) might be compromised by resistance. Results of the 96 week SECOND-LINE randomised trial showed that NtRTI-sparing ART with ritonavir-boosted lopinavir and raltegravir (raltegravir-group) provided non-inferior efficacy to ritonavir-boosted lopinavir and two or three NtRTIs (NtRTI-group) in participants with virological failure composed of a first-line regimen of a non-nucleoside reverse transcriptase inhibitor plus two NtRTIs. We report the relation of baseline virological resistance with virological failure and emergent resistance on study., Methods: As part of the randomised open-label SECOND-LINE trial, second-line ART NtRTI selection was made by either genotype (local laboratory) or algorithm. Genotypic resistance for the entire cohort at baseline was assessed on stored samples at a central laboratory. Virological failure was defined as plasma viral load greater than 200 copies per mL. Baseline viral isolates were assigned genotypic sensitivity scores (GSSs) by use of the Stanford HIV Database version 6.3.1: a global GSS (gGSS), defined as the combined GSS for lamivudine or emtricitabine, abacavir, zidovudine, stavudine, didanosine, and tenofovir and a specific GSS (sGSS) defined as the GSS for the ART regimen initiated by a specific participant. Emergent resistance was reported on samples with a viral load greater than 500 copies per mL. We used multivariate logistic regression with backward elimination to assess predictors of virological failure and emergent resistance., Findings: From April 19, 2010, to July 22, 2013, 271 patients were included in the NtRTI group and and 270 in the raltegravir group. In the NtRTI group 215 had available baseline sequence data, and 240 had viral load measurements at 96 weeks; in the raltegravir group 236 had baseline sequence data and 255 had viral load measurements at 96 weeks. Median (IQR) gGSS was 3.0 (1.3-4.3) in the NtRTI group and 3.0 (1.0-4.3) in the raltegravir group. The median sGSS in the NtRTI group was 1.0 (0.5-1.8). Multivariate analysis showed significant associations between virological failure and less than complete adherence at week 4 (odds ratio [OR] 2.18, 95%CI 1.07-4.47; p=0·03) and week 48 (2.49, 1.09-5.69; p=0.03), baseline plasma viral load greater than 100,000 copies per mL (3.43, 1.70-6.94; p=0.0006), baseline gGSS >4.25 (4.73, 1.94-11.6; p=0.0007), and being Hispanic (3.13, 1.21-8.13; p=0.02) or African (3.49, 1.68-7.28; p=0.0008) rather than Asian. We observed emergent major mutations in one (1%) of 129 participants for protease (both groups), eight (13%) of 64 for reverse transcriptase (NtRTI group) and 16 (20%) of 79 for integrase. Emergent resistance was associated with the raltegravir group (OR 2.47, 95% CI 1.02-5.99; p=0.05), baseline log10 viral load (1.83, 1.12-2.97; p=0.02), and absence of the Lys65Arg (K65R) or Lys70Glu (K70E) mutation at baseline (3.18, 1.12-9.02; p=0.03)., Interpretation: Poor adherence was a major determinant of virological failure in people on second-line ART. In settings with limited resources, investment in optimisation of adherence rather than implementation of drug resistance testing might be advisable., Funding: University of New South Wales Australia, Merck, AbbVie, and the Foundation for AIDS Research., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: We explored the relationship between virological response in the first year of treatment and long-term outcomes in the BENCHMRK studies., Methods: Patients failing antiretroviral treatment with 3-class resistant HIV-1 received double-blinded raltegravir (or placebo) with optimized background therapy (OBT) until week 156, followed by open-label raltegravir with OBT up to week 240. In this exploratory analysis of patients randomized to raltegravir, virological response over weeks 16-48 was categorized as continuous suppression (CS; viral RNA [vRNA] always <50 copies/ml), low-level viraemia (LLV; vRNA always <400 copies/ml, >50 copies/ml at least once), or not suppressed (NS; vRNA >400 copies/ml at least once). The association between these first-year vRNA response categories and baseline factors was analysed with univariate and multivariate models. Virological and immunological outcomes for years 2-5 were assessed by first-year vRNA response category (observed failure approach)., Results: Baseline vRNA, baseline CD4(+) T-cell count and rapid viral decay (vRNA <50 copies/ml between weeks 2-12) correlated with first-year vRNA response (P<0.001); only rapid viral decay remained significant by multiple regression. Virological response rates were similar in the LLV and CS groups and lowest in the NS group. CD4(+) T-cell count increased through week 240 in the CS and LLV groups. Time to loss of virological response (confirmed vRNA ≥400 copies/ml) through week 240 did not support as strong a difference between the LLV and CS groups (log-rank P=0.11) as previously reported through weeks 156 and 192 (P<0.05)., Conclusions: Treatment-experienced patients on a raltegravir-based regimen with early LLV may have long-term virological and immunological benefit when their therapy is maintained.

Local and centrally measured plasma HIV RNA (pVL) were assessed for agreement in two trials, ENCORE1 and SECOND-LINE. The proportion less than 200 copies/ml at week 48 was qualitatively similar [ENCORE1 2.5% (95% confidence interval, 95% CI –1.6 to 6.6); 1.9% (95% CI –1.9 to 2.1); SECOND-LINE 0.3% (95% CI –6.4 to 10.0); 1.8% (95% CI –4.7 to 8.3)]. The mean difference in log10 pVL copies/ml at weeks 0 and 48 was less than 0.2 log10 copies/ml in both trials. Our data indicate that central testing of pVL in HIV therapeutic trials is not warranted.

Human Ag-specific CD4(+) T cells can be detected by their dual expression of CD134 (OX40) and CD25 after a 44 hours stimulation with cognate Ag. We show that surface expression of CD39 on Ag-specific cells consistently identifies a substantial population of CD4(+) CD25(+) CD134(+) CD39(+) T cells that have a Treg-cell-like phenotype and mostly originate from bulk memory CD4(+) CD45RO(+) CD127(low) CD25(high) CD39(+) Treg cells. Viable, Ag-specific CD25(+) CD134(+) CD39(+) T cells could be expanded in vitro as cell lines and clones, and retained high Forkhead Box Protein 3, CTLA-4 and CD39 expression, suppressive activity and Ag specificity. We also utilised this combination of cell surface markers to measure HIV-Gag responses in HIV(+) patients before and after anti-retroviral therapy (ART). Interestingly, we found that the percentage of CD39(-) cells within baseline CD4(+) T-cell responses to HIV-Gag was negatively correlated with HIV viral load pre-ART and positively correlated with CD4(+) T-cell recovery over 96 weeks of ART. Collectively, our data show that Ag-specific CD4(+) CD25(+) CD134(+) CD39(+) T cells are highly enriched for Treg cells, form a large component of recall responses and maintain a Treg-cell-like phenotype upon in vitro expansion. Identification and isolation of these cells enables the role of Treg cells in memory responses to be further defined and provides a development pathway for novel therapeutics., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Objective: Maraviroc, a chemokine co-receptor type 5 (CCR5) antagonist, has demonstrated comparable efficacy and safety to efavirenz, each in combination with zidovudine/lamivudine, over 96 weeks in the Maraviroc vs. Efavirenz Regimens as Initial Therapy (MERIT) study. Here we report 5-year findings., Design: A randomized, double-blind, multicenter phase IIb/III study with an open-label extension phase., Methods: Treatment-naive patients with CCR5-tropic HIV-1 infection (Trofile) received maraviroc 300 mg twice daily or efavirenz 600 mg once daily, and zidovudine/lamivudine 300 mg/150 mg twice daily. After the last patient's week 96 visit, the study was unblinded and patients could enter a nominal 3-year open-label phase. Endpoints at the 5-year nominal visit (week 240) included proportion of patients (CCR5 tropism re-confirmed by enhanced sensitivity Trofile) with viral load (plasma HIV-1 RNA) below 50 and 400 copies/ml, and change from baseline in CD4(+) cell count, as well as safety., Results: The proportion of patients maintaining viral load below 50 copies/ml was similar between treatment arms throughout the study and at week 240 (maraviroc 50.8% vs. efavirenz 45.9%). Maraviroc-treated patients had a greater increase from baseline in mean CD4(+) cell count than efavirenz-treated patients at week 240 (293 vs. 271 cells/μl, respectively). Fewer patients on maraviroc vs. efavirenz experienced treatment-related adverse events (68.9 vs. 81.7%) and discontinued as a result of any adverse event (10.6 vs. 21.3%)., Conclusion: Maraviroc maintained similar long-term antiviral efficacy to efavirenz over 5 years in treatment-naive patients with CCR5-tropic HIV-1. Maraviroc was generally well tolerated with no unexpected safety findings or evidence of long-term safety concerns.

Unlabelled: The latent HIV reservoir is a major impediment to curing HIV infection. The contribution of CD4(+) T cell activation status to the establishment and maintenance of the latent reservoir was investigated by enumerating viral DNA components in a cohort of 12 individuals commencing antiretroviral therapy (ART) containing raltegravir, an integrase inhibitor. Prior to ART, the levels of total HIV DNA were similar across HLA-DR(+) and HLA-DR(-) (HLA-DR(±)) CD38(±) memory CD4(+) T cell phenotypes; episomal two-long terminal repeat (2-LTR) HIV DNA levels were higher in resting (HLA-DR(-) CD38(-)) cells, and this phenotype exhibited a significantly higher ratio of 2-LTR to integrated HIV DNA (P = 0.002). After 1 year of ART, there were no significant differences across each of the memory phenotypes of any HIV DNA component. The decay dynamics of integrated HIV DNA were slow within each subset, and integrated HIV DNA in the resting HLA-DR(-) CD38(-) subset per mm(3) of peripheral blood exhibited no significant decay (half-life of 25 years). Episomal 2-LTR HIV DNA decayed relative to integrated HIV DNA in resting cells with a half-life of 134 days. Surprisingly, from week 12 on, the decay rates of both total and episomal HIV DNA were lower in activated CD38(+) cells. By weeks 24 and 52, HIV RNA levels in plasma were most significantly correlated with the numbers of resting cells containing integrated HIV DNA. On the other hand, total HIV DNA levels in all subsets were significantly correlated with the numbers of HLA-DR(+) CD38(-) cells containing integrated HIV DNA. These results provide insights into the interrelatedness of cell activation and reservoir maintenance, with implications for the design of therapeutic strategies targeting HIV persistence., Importance: It is generally believed that HIV is not cleared by extensive antiretroviral therapy (ART) due to the difficulty in eradicating the latent reservoir in resting CD4(+) T cells. New therapies that attempt to activate this reservoir so that immune or viral cytopathic mechanisms can remove those infected cells are currently being investigated. However, results obtained in this research indicate that activation, at least on some level, already occurs within this reservoir. Furthermore, we are the first to describe the dynamics of different HIV DNA species in resting and activated memory CD4+ T cell subsets that point to the role different levels of activation play in maintaining the HIV reservoir.

Memory CD4(+) T lymphocytes in peripheral blood that express integrins α4ß7 preferentially recirculate through gut-associated lymphoid tissue (GALT), a proposed site of significant HIV-1 replication. Tregs and activated CD4(+) T cells in GALT could also be particularly susceptible to infection. We therefore hypothesized that infection of these subsets of memory CD4(+) T cells may contribute disproportionately to the HIV-1 reservoir. A cross-sectional study of CD4(+) T cell subsets of memory CD45RO(+) cells in peripheral blood mononuclear cells (PBMCs) was conducted using leukapheresis from eight subjects with untreated chronic HIV-1 infection. Real-time polymerase chain reaction (PCR) was used to quantify total and integrated HIV-1 DNA levels from memory CD4(+) T cells sorted into integrin β7(+) vs. β7(-), CD25(+)CD127(low) Treg vs. CD127(high), and activated CD38(+) vs. CD38(-). More than 80% of total HIV-1 DNA was found to reside in the integrin β7-negative non-gut-homing subset of CD45RO(+) memory CD4(+) T cells. Less than 10% was found in highly purified Tregs or CD38(+) activated memory cells. Similarly, integrated HIV-1 DNA copies were found to be more abundant in resting non-gut-homing memory CD4(+) T cells (76%) than in their activated counterparts (23%). Our investigations showed that the majority of both total and integrated HIV-1 DNA was found within non-gut-homing resting CD4(+) T cells.

Antibody-dependent cellular cytotoxicity (ADCC) is potentially an effective adaptive immune response to HIV infection. However, little is understood about the role of ADCC in controlling chronic infection in the small number of long-term slow-progressors (LTSP) who maintain a relatively normal immunological state for prolonged periods of time. We analysed HIV-specific ADCC responses in sera from 139 HIV(+) subjects not on antiretroviral therapy. Sixty-five subjects were LTSP, who maintained a CD4 T-cell count > 500/μl for over 8 years after infection without antiretroviral therapy and 74 were non-LTSP individuals. The ADCC responses were measured using an natural killer cell activation assay to overlapping HIV peptides that allowed us to map ADCC epitopes. We found that although the magnitude of ADCC responses in the LTSP cohort were not higher and did not correlate with CD4 T-cell depletion rates, the LTSP cohort had significantly broader ADCC responses compared with the non-LTSP cohort. Specifically, regulatory/accessory HIV-1 proteins were targeted more frequently by LTSP. Indeed, three particular ADCC epitopes within the Vpu protein of HIV were recognized only by LTSP individuals. Our study provides evidence that broader ADCC responses may play a role in long-term control of HIV progression and suggests novel vaccine targets., (© 2012 The Authors. Immunology © 2012 Blackwell Publishing Ltd.)

Objective: A 96-week clinical study was planned to estimate the antiviral activity and safety of lersivirine in treatment-naive HIV-1-infected patients., Methods: This ongoing international, multicenter, double-blind, randomized, Phase IIb exploratory study evaluates the efficacy and safety of 2 doses of lersivirine or 1 of efavirenz, each combined with tenofovir disoproxil fumarate/emtricitabine. Patients were randomized 1:1:1 to receive lersivirine (500 or 750 mg once daily) or efavirenz (600 mg once daily), each administered with tenofovir disoproxil fumarate/emtricitabine (300 mg/200 mg, once daily). The primary endpoint is the proportion of patients with HIV-1 RNA <50 copies per milliliter (missing/discontinuation = failure) at week 48., Results: For the 193 patients in the study, baseline mean plasma HIV-1 RNA was 4.7 log10 copies per milliliter, and median CD4 cell count was 312 cells per cubic millimeter. At week 48, the percentage of patients with HIV-1 RNA <50 copies per milliliter was 78.5% (51/65), 78.5% (51/65), and 85.7% (54/63) in the lersivirine 500 mg, 750 mg, and efavirenz groups, respectively. CD4 cell count changes from baseline were similar across groups. Virologic failure occurred in 7 patients (11%) in each of the lersivirine groups and 3 patients (5%) in the efavirenz group. The pattern of lersivirine resistance was distinct from other nonnucleoside reverse transcriptase inhibitors. Overall incidences of all-causality treatment-related or grade 3/4 adverse events (AEs) or AE-related discontinuations were lower with lersivirine than with efavirenz, and serious AEs occurred at similar rates across treatment groups., Conclusions: Both lersivirine doses showed broadly comparable efficacy to efavirenz over 48 weeks in treatment-naive patients, with different AE profiles from efavirenz.

A recent investigation of the effect of different antiretroviral drug classes on first phase dynamics of HIV RNA plasma virus levels has indicated that drugs acting at stages closer to viral production, such as the integrase inhibitor raltegravir, can produce a steeper first phase decay slope that may not be due to drug efficacy. Moreover it was found that for most drug classes the first phase transitions from a faster (phase IA) to a slightly slower decay region (phase IB) before the start of the usual second phase. Neither of these effects has been explained to date. We use a mathematical model that incorporates the different stages of the HIV viral life cycle in CD4+ T cells: viral entry, reverse transcription, integration, and viral production, to investigate the intracellular HIV mechanisms responsible for these complex plasma virus decay dynamics. We find differences in the phase IA slope across drug classes arise from a higher death rate of cells when they enter the productively infected stage post-integration, with a half-life of approximately 8 hours in this stage, whereas cells in earlier stages of the infection cycle have half-lives similar to uninfected cells. This implies any immune clearance is predominantly limited to the productive infection stage. We also show that the slowing of phase IA to phase IB at day 2 to 4 of monotherapy, depending on drug class, is a result of new rounds of infection. The level at which this slowing occurs is a better indicator of drug efficacy than the slope of the initial decay.

Objective: We investigated the dynamics of HIV RNA and HIV DNA levels after the commencement of raltegravir-based antiretroviral therapy (ART) in primary (PHI) and chronically HIV-infected (CHI) individuals (the PINT study)., Design: We recruited 8 PHI and 8 CHI ART-naive individuals who commenced a 1-year combination regimen of Truvada and the integrase inhibitor raltegravir., Methods: Nonlinear mixed effects modelling was used to determine multiphasic decay of plasma HIV RNA levels (pVL), as well as dynamics of total, episomal [2-long terminal repeats (LTR)] and integrated HIV DNA in CD4 T cells from peripheral blood., Results: Although pVL decreased faster through first and second phase for PHI individuals there was no difference in the final level reaching a mean of 9 copies/ml by week 16 that was maintained thereafter. Total HIV DNA and integrated HIV DNA levels from CHI patients were significantly higher than from PHI patients. However, at no time did 2-LTR levels differ between groups. Of note, 2-LTR circles exhibited an initial increase peaking at week 3 followed by biphasic decay with a half-life of 29 days. Second phase integrated HIV DNA levels were significantly correlated with duration of infection and consistent with this form of infection occurring at approximately 100 000 integration events per day in the absence of ART, achieving its 50% level 2 years after infection., Conclusions: Integrated HIV DNA levels accumulate with duration of untreated HIV infection. The relatively short half-life and high levels of 2-LTR circles after 1 year support continued HIV transmission during ART.

Background: Current HIV-1 antiretroviral therapy (ART) greatly reduces virus replication but does not significantly affect the viral reservoir. Raltegravir, a recently introduced integrase inhibitor, could, at least theoretically, reduce residual viremia in patients on ART and affect the viral reservoir size. The aim of this study was to assess whether switching therapy in treatment-experienced patients that were virally suppressed to a raltegravir-containing regimen reduces the size of the viral reservoir, and if such treatment leads to a change in levels of HIV 2-LTR circles in this patient group., Methods: 14 ART experienced individuals with a suppressed viral load (<50 HIV-1 RNA copies/mL plasma) at baseline (for at least 2 months) were switched to a raltegravir-containing regimen. Blood samples were taken at baseline and at ≥2 timepoints up to 48±6 weeks. Levels of total HIV-1 DNA and 2-LTR circles in peripheral blood mononuclear cells (PBMCs) were measured using real-time PCR assays., Results: There was no significant change in HIV-1 total DNA levels over the study duration (p = 0.808), median slope 0.24 (conservative nonparametric 95% CI: -11.78, 26.23). Low levels of 2-LTR circles were detected in 2 patients. One had 16 copies/10(6) PBMCs at baseline and the other had 34 copies/10(6) PBMCs at week 51., Conclusions: The switch to a raltegravir containing regimen was not associated with a significant change in HIV-1 total DNA levels in this cohort. There were no observed changes in the levels of HIV-1 2-LTR circles associated with raltegravir treatment initiation.

Background: Eradication of HIV-1 is prevented by the formation of viral reservoirs in peripheral blood, lymphoid tissues and other sanctuary sites. In most patients, rebound upon treatment cessation is prompt. We assessed whether early treatment with raltegravir can impact on the formation of the viral reservoir., Methods: We conducted an open-label, nonrandomized study, and assessed in detail the decay characteristics of HIV-1 RNA in plasma, HIV DNA in CD4 T cells and colon tissue biopies (CTBs) in 16 treatment-naive patients during either primary (PHI, n = 8) or chronic (CHI, n = 8) HIV-1 infection after treatment with raltegravir and Truvada for 52 weeks., Results: HIV-1 RNA decreased rapidly with treatment in all patients; first and second phase levels were lower in PHI patients with no appreciable difference in residual viremia between the two groups at 52 weeks. Episomal HIV-1 DNA increased sharply in both groups with peak levels at 3-4 weeks. Total HIV-1 DNA levels were reduced in both groups with similar kinetics, but were markedly lower in PHI patients after 52 weeks. Integrated HIV-1 DNA levels were significantly lower at baseline in PHI patients and this difference widened on treatment. Finally, total HIV-1 DNA decayed substantially in both groups in CTB., Conclusion: Treatment with raltegravir resulted in a large number of abrogated integration events, reflected by the increase of episomal HIV-1 DNA after treatment initiation. Levels of total and integrated HIV-1 DNA were lower in PHI patients at the end of the study period.

Objective: The aim of the study was to evaluate the predictive value of clinical and molecular risk factors, including peripheral blood mononuclear cell (PBMC) mitochondrial DNA (mtDNA) and mitochondrial RNA (mtRNA), for the development of lactic acidosis (LA) and symptomatic hyperlactataemia (SHL)., Methods: In a substudy of a large multicentre, randomized trial of three antiretroviral regimens, all containing didanosine (ddI) and stavudine (d4T), in antiretroviralnaïve, HIV-1-infected patients, patients with LA/SHL ('cases') were compared with those without LA/SHL in a univariate analysis, with significant parameters analysed in a multivariate model. In a molecular substudy, PBMC mtDNA and mtRNA from cases and matched controls at baseline and time of event were examined., Results: In 911 subjects followed for a median of 192 weeks, 24 cases were identified (14 SHL and 10 LA). In univariate analysis, cases were more likely to be female (P=0.05) and to have a high body mass index (BMI) (P=0.02). In multivariate analyses, only BMI remained an independent predictor of the development of LA/SHL (P=0.03). Between cases and controls there was no significant difference in mtDNA copy number at baseline (389 vs. 411 copies/cell, respectively; P=0.60) or at time of event (329 vs. 474 copies/cell, respectively; P=0.21), in the change in mtDNA copy number from baseline to event (-65 vs. +113 copies/cell, respectively; P=0.12), in mtRNA expression at baseline or time of event, or in the change in mtRNA expression from baseline to event., Conclusion: The development of LA/SHL was associated with increased BMI, but PBMC mtDNA and mtRNA did not predict LA/SHL. This demonstrates the ineffectiveness of routine measurement of PBMC mtDNA in patients on ddI and d4T as a means of predicting development of LA/SHL., (2011 British HIV Association.)

We have previously reported induction of transcriptional gene silencing (TGS) of HIV-1 by short hairpin RNA (shRNA) expressed in MOLT-4 cells. The shRNA (termed shPromA) targets the highly conserved tandem NF-kB binding sequences of the HIV-1 promoter. Recent articles have reported that TGS mediated by promoter-targeted siRNAs was exclusively the result of sequence non-specific off-target effects. Specifically, several mismatched siRNAs to the target promoter sequences were reported to also induce significant TGS, suggesting TGS was a consequence of off-target effects. Here, following extensive investigation, we report that shPromA induces sequence specific transcriptional silencing in HIV-1 infection in MOLT4 cells, while four shRNA variants, mismatched by 2-3 nucleotides, fail to suppress viral replication. We confirm similar levels of shRNA expression from the U6 promoter and the presence of processed/cleaved siRNAs for each construct in transduced MOLT-4 cells. HIV-1 sequence specific shPromA does not suppress HIV-2, which has an alternate NF-kB binding sequence. As a result of the unique sequence targeted, shPromA does not induce down-regulation of other NF-kB driven genes, either at the mRNA or protein level. Furthermore, we confirmed shPromA does not have sequence non-specific off-target effects through unaltered expression of CD4, CXCR4, and CCR5, which are used for viral entry. Additionally, shPromA does not alter PKR, IFN levels, and three downstream mediators of IFN-a response genes. Our data clearly shows that shPromA achieved highly specific TGS of HIV-1, demonstrating that effective TGS can be induced with minimal off-target effects.

Objectives: Apricitabine (ATC) is a novel deoxycytidine analogue nucleoside reverse transcriptase inhibitor (NRTI) with significant antiviral activity in vitro, including activity against HIV-1 with reverse transcriptase mutations that confer resistance to other NRTIs. ATC has shown promising antiviral activity and good tolerability when given as monotherapy for 10 days in treatment-naïve HIV-1-infected patients., Methods: In this Phase II randomized, double-blind study, 51 treatment-experienced HIV-1-infected patients with the reverse transcriptase mutation M184V who were failing therapy which included lamivudine (3TC) were randomized to receive twice-daily 600 mg ATC, 800 mg ATC or 150 mg 3TC for 21 days. Patients remained on their existing background regimen until day 21, when background therapy could be optimized according to genotype at screening., Results: At day 21, the mean change in viral load was -0.71 and -0.90 log(10) HIV-1 RNA copies/mL in the 600 and 800 mg ATC groups, respectively, compared with a -0.03 log(10) change in the 3TC group. In patients with at least three thymidine analogue mutations (TAMs) at baseline, greater reductions in viral load were observed in the 800 mg ATC group at day 21 than in the 600 mg ATC group. Few genotypic changes were detected at day 21 [two patients (600 mg ATC) lost and three patients (800 mg ATC) gained a TAM] and all patients with detectable virus retained the M184V mutation. The safety profiles of the two ATC doses were similar to that of 3TC., Conclusions: Over the 21-day treatment period, ATC showed promising antiviral activity and was well tolerated in treatment-experienced patients with M184V, with or without additional TAMs., (© 2010 British HIV Association.)

Objective: Antiretroviral therapy (ART) management for HIV-infected children is critical in many resource-constrained countries. We investigated the cost-effectiveness and cost-utility of different frequencies of monitoring plasma viral load among HIV-positive children initiating ART in a resource-limited setting., Design/methods: A stochastic agent-based simulation model was built and directly informed by a cohort of 304 HIV-infected children starting ART in Thailand between 2001 and 2009. The model simulated the expected costs and clinical outcomes over time according to different viral load monitoring frequencies and initiation of second-line therapies when appropriate., Results: The optimal frequency of viral load monitoring was found to be annual, after a single screening at 6 months. Associated costs of viral load monitoring and appropriate ART would approximately triple current treatment costs. Compared with current conditions, a single screening during the first year of ART led to a 58.4% reduction in the total person-years of virological failure with annual monitoring leading to a 76.6% reduction. The incremental cost per quality adjusted life year gained from the optimal monitoring frequency was estimated as US$ 68,084 when including costs of ART and US$ 7224 without ART costs. The estimated cost attributed to preventing 1 year of virological failure was US$ 3393 with ART costs and US$ 359 without ART costs., Conclusion: Even infrequent viral load monitoring is likely to provide substantial clinical benefit to HIV-infected children on ART. Viral load monitoring can be considered cost-effective in many resource-limited settings. However, the costs associated with second-line therapies could be a barrier to its economic feasibility.

Background and Objectives: Bacterial pneumonia still contributes to morbidity/mortality in HIV infection despite effective combination antiretroviral therapy (cART). Evaluation of Subcutaneous Interleukin-2 in a Randomized International Trial (ESPRIT), a trial of intermittent recombinant interleukin-2 (rIL-2) with cART vs. cART alone (control arm) in HIV-infected adults with CD4 counts ≥300cells/μL, offered the opportunity to explore associations between bacterial pneumonia and rIL-2, a cytokine that increases the risk of some bacterial infections., Methods: Baseline and time-updated factors associated with first-episode pneumonia on study were analysed using multivariate proportional hazards regression models. Information on smoking/pneumococcal vaccination history was not collected., Results: IL-2 cycling was most intense in years 1-2. Over ≈7 years, 93 IL-2 [rate 0.67/100 person-years (PY)] and 86 control (rate 0.63/100 PY) patients experienced a pneumonia event [hazard ratio (HR) 1.06; 95% confidence interval (CI) 0.79, 1.42; P=0.68]. Median CD4 counts prior to pneumonia were 570cells/μL (IL-2 arm) and 463cells/μL (control arm). Baseline risks for bacterial pneumonia included older age, injecting drug use, detectable HIV viral load (VL) and previous recurrent pneumonia; Asian ethnicity was associated with decreased risk. Higher proximal VL (HR for 1 log(10) higher VL 1.28; 95% CI 1.11, 1.47; P<0.001) was associated with increased risk; higher CD4 count prior to the event (HR per 100 cells/μL higher 0.94; 95% CI 0.89, 1.0; P=0.04) decreased risk. Compared with controls, the hazard for a pneumonia event was higher if rIL-2 was received <180 days previously (HR 1.66; 95% CI 1.07, 2.60; P=0.02) vs.≥180 days previously (HR 0.98; 95% CI 0.70, 1.37; P=0.9). Compared with the control group, pneumonia risk in the IL-2 arm decreased over time, with HRs of 1.41, 1.71, 1.16, 0.62 and 0.84 in years 1, 2, 3-4, 5-6 and 7, respectively., Conclusions: Bacterial pneumonia rates in cART-treated adults with moderate immunodeficiency are high. The mechanism of the association between bacterial pneumonia and recent IL-2 receipt and/or detectable HIV viraemia warrants further exploration., (© 2010 British HIV Association.)

Background: It is unknown whether sex and race influence clinical outcomes following primary human immunodeficiency virus type 1 (HIV-1) infection., Methods: Data were evaluated from an observational, multicenter, primarily North American cohort of HIV-1 seroconverters., Results: Of 2277 seroconverters, 5.4% were women. At enrollment, women averaged .40 log₁₀ fewer copies/mL of HIV-1 RNA (P < .001) and 66 more CD4(+) T cells/μL (P = .006) than men, controlling for age and race. Antiretroviral therapy (ART) was less likely to be initiated at any time point by nonwhite women and men compared to white men (P < .005), and by individuals from the southern United States compared to others (P = .047). Sex and race did not affect responses to ART after 6 months (P > .73). Women were 2.17-fold more likely than men to experience >1 HIV/AIDS-related event (P < .001). Nonwhite women were most likely to experience an HIV/AIDS-related event compared to all others (P = .035), after adjusting for intravenous drug use and ART. Eight years after diagnosis, >1 HIV/AIDS-related event had occurred in 78% of nonwhites and 37% of whites from the southern United States, and 24% of whites and 17% of nonwhites from other regions (P < .001)., Conclusions: Despite more favorable clinical parameters initially, female HIV-1-seroconverters had worse outcomes than did male seroconverters. Elevated morbidity was associated with being nonwhite and residing in the southern United States.

The CTL response in HLA-B*27(+) HIV-infected individuals is characterized by an immunodominant response to a conserved epitope in gag p24 (aa 263-272, KRWIILGLNK; KK10). Mutations resulting in substitution of the arginine (R264) at position 2 of this epitope have been identified as escape mutations. Nineteen HLA-B*27(+) long-term nonprogressors were identified from an Australian cohort with an average follow-up of 16 y following infection. Viral and host genetic factors impacting on disease progression were determined at multiple time points. Twelve of 19 had wild-type sequences at codon 264 at all time points; 7 of 19 carried CTL escape variants. Median viral load and CD4(+) T cell counts were not significantly different between these groups at enrollment. Viral load, as judged by levels at their last visit (1,700 and 21,000 RNA copies/ml, respectively; p = 0.01) or by time-weighted area under the curve was higher in the escape group (p = 0.02). Escape mutants at other HLA-B*27-restricted epitopes were uncommon. Moreover, host polymorphisms, such as CCR5Δ32, CCR2-64I, and SDF1-3'A, or breadth of TCR repertoire responding to KK10 did not segregate to wild-type or escape groups. Host and viral factors were examined for a relationship to viral load. The only factor to affect viral load was the presence of the R264 escape mutations at the immunodominant epitope. CTL escape at R264 in the KK10 epitope is a major determinant of subsequent viral load in these HLA-B*27(+) individuals.

CD8(+) T cells play a significant role in the control of HIV replication, yet the associated qualitative and quantitative factors that determine the outcome of infection remain obscure. In this study, we examined Ag-specific CD8(+) TCR repertoires longitudinally in a cohort of HLA-B*2705(+) long-term nonprogressors with chronic HIV-1 infection using a combination of molecular clonotype analysis and polychromatic flow cytometry. In each case, CD8(+) T cell populations specific for the immunodominant p24 Gag epitope KRWIILGLNK (KK10; residues 263-272) and naturally occurring variants thereof, restricted by HLA-B*2705, were studied at multiple time points; in addition, comparative data were collected for CD8(+) T cell populations specific for the CMV pp65 epitope NLVPMVATV (NV9; residues 495-503), restricted by HLA-A*0201. Dominant KK10-specific clonotypes persisted for several years and exhibited greater stability than their contemporaneous NV9-specific counterparts. Furthermore, these dominant KK10-specific clonotypes exhibited cross-reactivity with antigenic variants and expressed significantly higher levels of CD127 (IL-7Rα) and Bcl-2. Of note, we also found evidence that promiscuous TCR α-chain pairing associated with alterations in fine specificity for KK10 variants could contribute to TCR β-chain prevalence. Taken together, these data suggest that an antiapoptotic phenotype and the ability to cross-recognize variant epitopes contribute to clonotype longevity and selection within the peripheral memory T cell pool in the presence of persistent infection with a genetically unstable virus.

Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified >300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection.

Objective: The Simplification of antiretroviral therapy with Tenofovir-Emtricitabine or Abacavir-Lamivudine trial (STEAL) study randomized HIV participants to switch existing nucleoside reverse transcriptase inhibitors (NRTI) to either abacavir/lamivudine (ABC/3TC; n = 179) or tenofovir/emtricitabine (TDF/FTC; n = 178). An increased risk in cardiovascular disease (CVD) was reported (hazard ratio 7.7, P = 0.048) in ABC/3TC recipients compared with TDF/FTC in the STEAL study. The impact of ABC/3TC treatment on a range of CVD and inflammatory biomarkers was explored., Design and Methods: Biomarkers were assessed at 0, 12, 24, and 48 weeks to examine: inflammation - high sensitive C-reactive protein, amyloid-P, amyloid-A, interleukin 6, interleukin 10, interferon α, and macrophage migration inhibitory factor; coagulation - D-dimer and fibrinogen; platelet function - soluble P-selectin; endothelial function - vascular cell adhesion molecule 1 and intercellular adhesion molecule 1; renal function - cystatin C. The primary endpoint was the difference between arms for mean change from baseline to week 12. Secondary analyses were differences between groups for mean change from baseline to weeks 24 and 48, time-weighted change from baseline to week 48, and changes to week 12 stratified by Framingham CVD risk score at baseline., Results: Sera were available from 330 (92%) of 357 participants. At baseline, all biomarkers were similar between treatment arms and when stratified for baseline NRTI exposure. There were no significant differences between treatment arms in the mean change from baseline to week 12 for any biomarkers. No consistent between-group differences were seen in the secondary analyses that could suggest one pathophysiological pathway., Conclusion: A thorough examination of selected biomarkers associated with cardiovascular morbidity and mortality did not reveal associations with the use of ABC/3TC relative to use of TDF/FTC.

Background: Previously demonstrated safe and highly immunogenic in non-human primates, this study assessed DNA (pHIS-HIV-AE) prime, recombinant fowlpox (rFPV-HIV-AE) boost vaccines in humans., Results: Eight participants (6 active vaccine, 2 placebo) received all vaccinations; local and systemic reactions were mild to moderate. The percentage CD4(+) and CD8(+) T cells responding to HIV-1 Gag antigens by ICS (mean ± SD) was 0.16 ± 0.12 and 0.10 ± 0.12 for active and 0.01 ± 0.01 and 0.00 ± 0.00 for placebo vaccine respectively. The percentage of T cells responding did not reach pre-defined thresholds to be considered positive responses. Consequently, the Data Safety Monitoring Board recommended cessation of further recruitment. Existing volunteers were followed to 52 weeks., Methods: Vectors expressing homologous HIV-1 clade A/E gag, pol, env and regulatory genes or matched placebo were administered intramuscularly at weeks 0, 4, 8 (6 mg pHIS-HIV-AE) and week 12 (3.0 x 10(8) pfu rFPV-HIV-AE) in this randomized, double-blind, placebo-controlled phase I/IIa study in healthy Thai adults at low risk of HIV infection. Immunogenicity was determined by interferon-gamma and IL-2 expression using intracellular cytokine staining assay (ICS), 13 weeks after randomization. Interim analysis was performed when eight volunteers reached 16 weeks follow-up., Conclusions: Vaccine candidates were generally well tolerated, but showed limited immunogenicity. Better vaccines and delivery systems are required.

Objective: To investigate the relative predictive value of CD4(+) metrics for serious clinical endpoints., Design: Observational., Methods: Patients (3012; 20 317 person-years) from control arms of ESPRIT and SILCAAT were followed prospectively. We used Cox regression to identify CD4(+) metrics (latest, baseline and nadir CD4(+) cell count, latest CD4(+)%, time spent with CD4(+) count below certain thresholds and CD4(+) slopes) independently predictive of all-cause mortality, non-AIDS deaths, non-AIDS (cardiovascular, hepatic, renal and non-AIDS malignancy) and AIDS events. Akaike information criteria (AIC) were calculated for each model. Significant metrics (P < 0.05) were then additionally adjusted for latest CD4(+) cell count., Results: Non-AIDS deaths occurred at a higher rate than AIDS deaths [rate ratio: 6.48, 95% confidence interval (CI) 5.1-8.1], and non-AIDS events likewise (rate ratio: 1.72, 95% CI 1.65-1.79). Latest CD4(+) cell count was strongly predictive of lower risk of death (hazard ratio per log2 rise: 0.48, 95% CI 0.43-0.54), with lowest AIC of all metrics. CD4(+) slope over seven visits, after additional adjustment for latest CD4(+) cell count, was the only metric to be an independent predictor for all-cause (hazard ratio for slope <-10 cells/microl per month vs. 0 +/- 10: 3.04, 95% CI 1.98-4.67) and non-AIDS deaths (hazard ratio for slope <-10 cells/microl per month vs. 0 +/- 10: 2.62, 95% CI 1.62-4.22). Latest CD4(+) cell count (per log(2) rise) was the best predictor across all four endpoints and predicted hepatic (hazard ratio 0.46, 95% CI 0.33-0.63) and renal events (hazard ratio 0.39, 95% CI 0.21-0.70), but not cardiovascular events (hazard ratio 1.05, 95% CI 0.77-1.43) or non-AIDS cancers (hazard ratio 0.78, 95% CI 0.59-1.03)., Conclusion: Latest CD4(+) cell count is the best predictor of serious endpoints. CD4(+) slope independently predicts all-cause and non-AIDS deaths.

Background: The MERIT (Maraviroc versus Efavirenz in Treatment-Naive Patients) study compared maraviroc and efavirenz, both with zidovudine-lamivudine, in antiretroviral-naive patients with R5 human immunodeficiency virus type 1 (HIV-1) infection., Methods: Patients screened for R5 HIV-1 were randomized to receive efavirenz (600 mg once daily) or maraviroc (300 mg once or twice daily) with zidovudine-lamivudine. Coprimary end points were proportions of patients with a viral load <400 and <50 copies/mL at week 48; the noninferiority of maraviroc was assessed., Results: The once-daily maraviroc arm was discontinued for not meeting prespecified noninferiority criteria. In the primary 48-week analysis (n = 721), maraviroc was noninferior for <400 copies/mL (70.6% for maraviroc vs 73.1% for efavirenz) but not for <50 copies/mL (65.3% vs 69.3%) at a threshold of -10%. More maraviroc patients discontinued for lack of efficacy (11.9% vs 4.2%), but fewer discontinued for adverse events (4.2% vs 13.6%). In a post hoc reanalysis excluding 107 patients (15%) with non-R5 screening virus by the current, more sensitive tropism assay, the lower bound of the 1-sided 97.5% confidence interval for the difference between treatment groups was above -10% for each end point., Conclusions: Twice-daily maraviroc was not noninferior to efavirenz at <50 copies/mL in the primary analysis. However, 15% of patients would have been ineligible for inclusion by a more sensitive screening assay. Their retrospective exclusion resulted in similar response rates in both arms Trial registration. ClinicalTrials.gov identifier: (NCT00098293) .

Background: To reduce lipid abnormalities and other side-effects associated with antiretroviral regimens containing lopinavir-ritonavir, patients might want to switch one or more components of their regimen. We compared substitution of raltegravir for lopinavir-ritonavir with continuation of lopinavir-ritonavir in HIV-infected patients with stable viral suppression on lopinavir-ritonavir-based combination therapy., Methods: The SWITCHMRK 1 and 2 studies were multicentre, double-blind, double-dummy, phase 3, randomised controlled trials. HIV-infected patients aged 18 years or older were eligible if they had documented viral RNA (vRNA) concentration below the limit of assay quantification for at least 3 months while on a lopinavir-ritonavir-based regimen. 707 eligible patients were randomly allocated by interactive voice response system in a 1:1 ratio to switch from lopinavir-ritonavir to raltegravir (400 mg twice daily; n=353) or to remain on lopinavir-ritonavir (two 200 mg/50 mg tablets twice daily; n=354), while continuing background therapy consisting of at least two nucleoside or nucleotide reverse transcriptase inhibitors. Primary endpoints were the mean percentage change in serum lipid concentrations from baseline to week 12; the proportion of patients with vRNA concentration less than 50 copies per mL at week 24 (with all treated patients who did not complete the study counted as failures) with a prespecified non-inferiority margin of -12% for each study; and the frequency of adverse events up to 24 weeks. Analyses were done according to protocol. These trials are registered with ClinicalTrials.gov, numbers NCT00443703 and NCT00443729., Findings: 702 patients received at least one dose of study drug and were included in the efficacy and safety analyses for the combined trials (raltegravir, n=350; lopinavir-ritonavir, n=352). Percentage changes in lipid concentrations from baseline to week 12 were significantly greater (p<0.0001) in the raltegravir group than in the lopinavir-ritonavir group in each study, yielding combined results for total cholesterol -12.6%vs 1.0%, non-HDL cholesterol -15.0%vs 2.6%, and triglycerides -42.2%vs 6.2%. At week 24, 293 (84.4%, 95% CI 80.2-88.1) of 347 patients in the raltegravir group had vRNA concentration less than 50 copies per mL compared with 319 (90.6%, 87.1-93.5) of 352 patients in the lopinavir-ritonavir group (treatment difference -6.2%, -11.2 to -1.3). Clinical and laboratory adverse events occurred at similar frequencies in the treatment groups. There were no serious drug-related adverse events or deaths. The only drug-related clinical adverse event of moderate to severe intensity reported in 1% or more of either treatment group was diarrhoea, which occurred in ten patients in the lopinavir-ritonavir group (3%) and no patients in the raltegravir group. The studies were terminated at week 24 because of lower than expected virological efficacy in the raltegravir group compared with the lopinavir-ritonavir group., Interpretation: Although switching to raltegravir was associated with greater reductions in serum lipid concentrations than was continuation of lopinavir-ritonavir, efficacy results did not establish non-inferiority of raltegravir to lopinavir-ritonavir., Funding: Merck., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Purpose of Review: To review current knowledge and the role of integrase inhibitors in the setting of HIV salvage therapy. We will discuss results from recent studies and literature and comment on the potential for integrase inhibitors in defined clinical settings., Recent Findings: Raltegravir has been studied most intensively in treatment-experienced patients and is the first integrase inhibitor that has been licensed for use in this patient group. Most studies have shown good tolerability data and very potent virus suppression. In patients with limited treatment options, switching from enfuvirtide appears to be well tolerated, whereas switching from a protease inhibitor-based regimen may increase the rates of viral failure. Elvitegravir also showed good results in early phase clinical trials and is currently undergoing phase III clinical trials., Summary: Given that integrase inhibitors belong to a new class of antiretroviral agents with a diverse drug resistance profile, and are active against both chemokine (C-C motif) receptor 5 and chemokine (C-X-C motif) receptor 4 strains, they are exciting additions to salvage therapy regimen. Raltegravir and elvitegravir are metabolized via different pathways, which will affect their respective use. The major limitation for the use of integrase inhibitors is a potentially low threshold for viral drug resistance, so functional monotherapy must be avoided.

Purpose: To study the impact of baseline resistance mutations and HIV-1 subtypes on virological response to first-line antiretroviral therapy and to analyse the concordance of the results of two antiretroviral resistance interpretation tools in the INITIO trial., Method: Genotype and virco TYPE resistance analyses were studied at baseline, Year 2, Year 3, and at first therapeutic failure on plasma specimens stored at -80 degrees C. Relations between resistance mutations at baseline, subtype, initial virological response, and virological outcome after Week 24 were studied., Results: 781 participants had genotypic results available at baseline. Therapeutic failure occurred for 112 participants. Initial virological response as well as virological outcome after Week 24 were not associated with HIV subtype. Before Week 24, the proportion of participants remaining under strict initial regimen was lower in patients with resistance mutations at baseline than in those without any resistance mutations. Presenceof resistance mutations at baseline also impacted negatively long-term virological outcome. Few discrepancies were observed between genotypic and virco TYPE for resistance interpretation., Conclusion: These data showed that presence of resistance mutations at baseline was associated with a poorer long-term virological outcome in the INITIO trial.

Hepatitis B virus (HBV)-specific T cells play a key role both in the control of HBV replication and in the pathogenesis of liver disease. Human immunodeficiency virus type 1 (HIV-1) coinfection and the presence or absence of HBV e (precore) antigen (HBeAg) significantly alter the natural history of chronic HBV infection. We examined the HBV-specific T-cell responses in treatment-naïve HBeAg-positive and HBeAg-negative HIV-1-HBV-coinfected (n = 24) and HBV-monoinfected (n = 39) Asian patients. Peripheral blood was stimulated with an overlapping peptide library for the whole HBV genome, and tumor necrosis factor alpha and gamma interferon cytokine expression in CD8+ T cells was measured by intracellular cytokine staining and flow cytometry. There was no difference in the overall magnitude of the HBV-specific T-cell responses, but the quality of the response was significantly impaired in HIV-1-HBV-coinfected patients compared with monoinfected patients. In coinfected patients, HBV-specific T cells rarely produced more than one cytokine and responded to fewer HBV proteins than in monoinfected patients. Overall, the frequency and quality of the HBV-specific T-cell responses increased with a higher CD4+ T-cell count (P = 0.018 and 0.032, respectively). There was no relationship between circulating HBV-specific T cells and liver damage as measured by activity and fibrosis scores, and the HBV-specific T-cell responses were not significantly different in patients with either HBeAg-positive or HBeAg-negative disease. The quality of the HBV-specific T-cell response is impaired in the setting of HIV-1-HBV coinfection and is related to the CD4+ T-cell count.

It is not fully elucidated whether patients who receive antiretroviral therapy (ART) can maintain continued CD4 count increases. Previous studies suggested a plateau 2-4 years after treatment initiation. We aimed to characterize the evolution of CD4 counts in HIV-infected individuals receiving long-term suppressive ART, by performing a retrospective study of patients who maintained viral suppression (HIV RNA <400 copies/ml) for > or =5 years. We used linear regression models to determine for each individual whether the CD4 count continued to increase or plateau. Furthermore, we estimated whether the slope of the CD4 count for each individual became zero, which we defined as the CD4 set-point. We assessed factors associated with continued CD4 count rise, reaching a CD4 set-point and time to the CD4 set-point. Fifty-nine patients were included. The median baseline CD4 count was 238 (IQR, 120-360) cells/microl and the median duration on ART was 7.6 (IQR, 5.9-9.3) years. On ART, CD4 count continued to increase in 37 subjects (63%). Significant predictors of continued CD4 count increase included a lower baseline log10 HIV RNA (OR, 0.35; 95% CI, 0.14-0.89; p=0.026) and a shorter duration on ART (OR, 0.65; 95% CI, 0.47-0.91; p=0.021). Twenty-four (41%) subjects reached a set-point after a median 4.3 (IQR 1.8-6.4) years on ART. A lower baseline CD4 percentage was associated with both a longer time to reach the CD4 set-point and a lower CD4 count at the CD4 set-point. These findings suggest that CD4 count may continue to increase in some patients after several years of ART. Our results point to an advantage to commencing ART at higher CD4+ T cell strata. These data should be considered when estimating the optimal time to initiate ART.

We previously reported prolonged HIV-1 transcriptional gene silencing by an RNA duplex targeting a sequence located within the NF-kappaB binding motif of the HIV-1 promoter in a susceptible HeLa cell line. Here we report extremely prolonged suppression of productive HIV-1 infection in a T-cell line (Molt-4) by a retrovirally delivered short-hairpin RNA (shRNA) targeting the same region (shkappaB). Following retroviral delivery of an shRNA we established shRNA-expressing CD4(+) T-cell lines. HIV-1 gene expression was profoundly suppressed for 1 year. Results of nuclear run-on assays and HIV-1 LTR-luciferase reporter assays revealed that shkappaB acted by inhibition of HIV-1 transcription. The effect was reversed by a histone deacetylase inhibitor, trichostatin-A (TSA), but not by a DNA methyltransferase inhibitor, 5-azacytidine (5-AzaC). Furthermore, chromatin immunoprecipitation assays (ChIP) demonstrated rapid, sustained induction of heterochromatin structures within the HIV-1 promoter region, with enrichment of histone 3 lysine 27 tri-methylation (H3K27me3) and H3K9 methylation. H3K27me3 enrichment was the most pronounced. This prolonged suppression could not be recapitulated by either retrovirally delivered anti-sense or sense strands alone or in combination. Our data strongly suggest that shkappaB induces high level, sustained transcriptional gene silencing of HIV-1 and offers the possibility of new therapeutic strategies.

Several dose-finding studies of boosted protease inhibitors have demonstrated that doses lower than those recommended in Caucasian populations exhibit in the Thai population similar pharmacokinetic (PK) properties with sustained virological suppression but reduced toxicity. We therefore evaluated the PK profiles of lower than the standard doses of atazanavir/ritonavir (ATV/RTV) in 22 adult Thai patients with well-suppressed human immunodeficiency virus 1 (HIV-1) infection. The PK parameters of ATV/RTV at a dosage of 200/100 mg once daily, plus two nucleoside reverse transcriptase inhibitors, were significantly lower than those associated with a dosage of 300/100 mg once daily in the same patients. In addition, the PK parameters for the lower dosage in these Thai patients were comparable to historical data from Caucasian cohorts who received the standard dose of ATV/RTV (300/100 mg). None of the patients showed subtherapeutic values of <0.15 mg/l at any time point. Bilirubin concentration decreased significantly after dose reduction, and viral load remained at <50 copies/ml in all subjects. Therefore, ATV/RTV at a dose of 200/100 mg once daily (plus appropriate backbone medication) warrants further long-term efficacy studies, particularly in patients of Thai and other Asian ethnicities.

Objectives: Poly-l-lactic acid (PLA) injections modestly increase objectively assessed facial thickness but not facial soft tissue volume (FSTV) over 24 weeks. The durability of this response has not been well defined objectively., Methods: HIV-infected lipoatrophic adults were randomized to four open-label PLA treatments administered every 2 weeks from week 0 (immediate group, n=50) or from week 24 (deferred group, n=50). Endpoints included FSTV assessed by computed tomography, facial lipoatrophy severity, quality of life (QoL) and safety. Analyses were by intention to treat., Results: Between weeks 24 and 48, soft tissue thickness increased modestly in injection planes, at the maxillary [mean 0.9 mm; 95% confidence interval (CI) 0.3-1.5 mm; P=0.007] and base of nasal septum levels (mean 0.4 mm; 95% CI 0.1-0.8; P=0.021), but not in untreated areas (P=0.79 and P=0.24). PLA durability assessed at week 48 in immediate group participants showed a mean change in FSTV of 14 cm(3) (95% CI-1 to 29 cm(3); P=0.060) and increased tissue depth at the maxillary (P<0.0001), base of nasal septum (P<0.0001) and mandibular (P=0.0035) levels. At week 48, clinicians and patients subjectively assessed facial lipoatrophy severity as reduced in immediate participants (83 and 91%, respectively), and the Mental Health scale score of the Short Form-36 Health Survey improved significantly in immediate participants relative to deferred participants (P=0.027). Subcutaneous injection-site nodule incidence at 48 weeks was 10%., Conclusions: PLA treatment benefits were durable, with objectively assessed modest increases in facial volume and tissue thickness sustained over 48 weeks in injection planes but not in other facial areas. Improvements in some QoL domains were maintained.

Gene transfer has potential as a once-only treatment that reduces viral load, preserves the immune system and avoids lifetime highly active antiretroviral therapy. This study, which is to our knowledge the first randomized, double-blind, placebo-controlled, phase 2 cell-delivered gene transfer clinical trial, was conducted in 74 HIV-1-infected adults who received a tat-vpr-specific anti-HIV ribozyme (OZ1) or placebo delivered in autologous CD34+ hematopoietic progenitor cells. There were no OZ1-related adverse events. There was no statistically significant difference in viral load between the OZ1 and placebo group at the primary end point (average at weeks 47 and 48), but time-weighted areas under the curve from weeks 40-48 and 40-100 were significantly lower in the OZ1 group. Throughout the 100 weeks, CD4+ lymphocyte counts were higher in the OZ1 group. This study indicates that cell-delivered gene transfer is safe and biologically active in individuals with HIV and can be developed as a conventional therapeutic product.

Objective: The aim of the study was to determine the effect of nucleoside reverse transcriptase inhibitors (NRTIs) on CD4 recovery in HIV-1-infected individuals receiving long-term suppressive combination antiretroviral therapy (cART)., Methods: A retrospective cohort study was carried out. The mean time-weighted CD4 change from baseline was determined at weeks 48, 96 and 144: its associations with exposure to NRTIs were assessed using linear regression., Results: One hundred and five patients were included. Their median baseline CD4 count was 225 (interquartile range 91-362) cells/microL. A trend of greater CD4 change from baseline was observed for individuals who at baseline had CD4 counts >200 cells/microL (138 vs. 113, 176 vs. 134 and 204 vs. 173 cells/microL), or were 0.05. Lower CD4 increases were observed in patients exposed to didanosine (ddI) or a combination of ddI and stavudine, although the difference was not statistically significant. For patients that commenced cART with CD4 count