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Significant progress has been made in the diagnostics and treatment of AIDS since the discovery of the human immunodeficiency virus type 1 (HIV-1) in 1983. The remarkable effectiveness of combined antiretroviral therapy (cART) is evidenced by mortality reduction, control of peripheral blood viral load, and in a nearly normal quality of HIV patients' lives. Remaining obstacles in treatment and cure are drug toxicities and side effects, viral resistance, persistence of HIV-1 reservoirs on termination of cART treatment, the cost of lifelong antiretroviral therapy, and the stigma associated with taking antiretroviral drugs. As determined by plasma viral RNA and peripheral blood mononuclear cells (PBMC) proviral DNA, we show improved suppression of productive HIV infection in human CD34 + hematopoietic stem cell-engrafted NOD (nonobese diabetic)-SCID (severe combined immunodeficiency)-il2rg -/- (NSG) mice by combined treatment with cART and CCR5 targeting drugs, compared with cART alone, as well as an increased preservation of human CD4 + T cells (defined as CD45 + CD3 + CD4 + cells) and CD4 + /CD8 + cell ratios in infected mice. The data also suggest a possible reduction in viral reservoirs. Our data confirm that this animal model is suitable for detection of productive HIV infection, replication, and establishment of viral reservoirs. The data also provide proof of principle for the utility of combining CCR5 targeting drugs, maraviroc and rapamycin, with traditional cART to improve control of viremia and reduce viral reservoirs. This study thus serves as a model for future HIV-1 studies that could lead to the clinical development of new generations of antiretroviral drugs.

The Rwanda national HIV program has been successful at scaling up antiretroviral therapy (ART) to achieve universal access. The AIDSRelief Model of Care focuses on four key principles: (1) earlier initiation of ART; (2) use of durable, highly-potent, and sequence-friendly first-line ART regimens; (3) early detection of treatment failure; and (4) provision of community-based care and support to ensure optimal adherence and follow up/engagement in care. We conducted a retrospective cohort study of randomly-selected HIV-infected patients at AIDSRelief-supported sites using a stratified, random sample of 583 adults (>15 years) who initiated ART from 30 June 2008 to 1 February 2010. At ART initiation, the median patient age was 38 years, and 67% were female. The baseline median CD4+ cell count was 309 cells/mm 3 . Overall virologic suppression was 91%. Married/ever married status (adjusted prevalence odds ratio [aPOR] 3.75, 95% confidence interval [CI] 1.30-10.78) and self-reported adherence ≥95% in the past month (aPOR 2.76, 95% CI 1.00-7.62) were significantly associated with viral suppression in the multivariable model. Excellent virologic outcomes were achieved in Rwandan AIDSRelief sites utilizing the AIDSRelief Model of Care during the scale-up of ART in the country.

Objectives: To compare the effectiveness of HIV integrase inhibitor monotherapy between raltegravir and dolutegravir as an approach to simplify therapy., Methods: We evaluated and compared the efficacy of 20 week monotherapy with dolutegravir or raltegravir in humanized mice (HSC-NSG) infected with HIVBaL. Plasma HIV RNA was measured by quantitative RT-PCR (limit of detection of 150 copies/45 μL of plasma) and drug levels by LC-MS/MS. Escape viruses were genotyped and analysed for replication capacity and drug susceptibility in tissue culture., Results: Drug-untreated control mice maintained constant viraemia throughout the study. Virus isolates from these mice were susceptible to both raltegravir (EC50 of <8 nM) and dolutegravir (EC50 of <1 nM). Mice treated with raltegravir or dolutegravir had plasma drug levels comparable to those in humans. Monotherapy with raltegravir initially suppressed HIV viraemia, but failed to maintain suppression in 4/4 mice. Viruses from raltegravir failing mice developed mutations G140G/S and Q148H/K, and were resistant to both raltegravir (EC50 values of >100 nM) and dolutegravir (EC50 values ranging from 8.8 to 13.3 nM). Monotherapy with dolutegravir suppressed viraemia in 5/5 of mice, but viraemia rebounded in one animal. The virus from this mouse had mutations E138K, G140S, Q148H, N155H and S230R, was highly resistant to both raltegravir (EC50 of >1000 nM) and dolutegravir (EC50 of 550 nM), and replicated to levels similar to those of control viruses in PBMCs., Conclusions: Monotherapy with either raltegravir or dolutegravir does not consistently maintain HIV suppression, suggesting that dual therapy may be required in simplification strategies., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Successful propagation of HIV in the human host requires entry into a permissive cell, reverse transcription of viral RNA, integration into the human genome, transcription of the integrated provirus, and assembly/release of new virus particles. Currently, there are antiretrovirals against each of these viral steps, except for provirus transcription. An inhibitor of HIV transcription could both increase potency of treatment and suppress drug-resistant strains. Cellular cyclin-dependent kinase 9 (CDK9) serves as a cofactor for the HIV Tat protein and is required for effective transcription of the provirus. Previous studies have shown that the CDK9 inhibitor Indirubin 3'-monoxime (IM) inhibits HIV transcription in vitro and in short-term in vivo studies of HIV acute infection in humanized mice (PBMC-NSG model), suggesting a therapeutic potential. The objective of this study is to evaluate the toxicity, pharmacokinetics and long-term antiviral activity of IM during chronic HIV infection in humanized mice (HSC-NSG model). We show that IM concentrations above EC50 values are rapidly achieved and sustained for > 3 h in plasma, and that non-toxic concentrations durably reduce HIV RNA levels. In addition, IM enhanced the antiviral activity of antiretrovirals from the reverse transcriptase, protease and integrase inhibitor classes in in vitro infectivity assays. In summary, IM may enhance current antiretroviral treatments and could help achieve a "functional cure" in HIV patients by preventing expression of proviruses.

Objective: To evaluate HIV drug resistance (HIVDR) and determinants of virological failure in a large cohort of patients receiving first-line tenofovir-based antiretroviral therapy (ART) regimens., Methods: A nationwide retrospective cohort from 42 health facilities was assessed for virological failure and development of HIVDR mutations. Data were collected at ART initiation and at 12 months of ART on patients with available HIV-1 viral load (VL) and ART adherence measurements. HIV resistance genotyping was performed on patients with VL ≥1000 copies/ml. Multiple logistic regression was used to determine factors associated with treatment failure., Results: Of 828 patients, 66% were women, and the median age was 37 years. Of the 597 patients from whom blood samples were collected, 86.9% were virologically suppressed, while 11.9% were not. Virological failure was strongly associated with age <25 years (adjusted odds ratio [aOR]: 6.4; 95% confidence interval [CI]: 3.2-12.9), low adherence (aOR: 2.87; 95% CI: 1.5-5.0) and baseline CD4 counts <200 cells/μl (aOR 3.4; 95% CI: 1.9-6.2). Overall, 9.1% of all patients on ART had drug resistance mutations after 1 year of ART; 27% of the patients who failed treatment had no evidence of HIVDR mutations. HIVDR mutations were not observed in patients on the recommended second-line ART regimen in Rwanda., Conclusions: The last step of the UNAIDS 90-90-90 target appears within grasp, with some viral failures still due to non-adherence. Nonetheless, youth and late initiators are at higher risk of virological failure. Youth-focused programmes could help prevent further drug HIVDR development., (© 2016 John Wiley & Sons Ltd.)

We have previously shown that FLSC, a chimeric protein containing HIV-1BAL gp120 and the D1 and D2 domains of human CD4, blocks the binding and entry of HIV-1 into target cells by occluding CCR5, the major HIV-1 coreceptor. In an effort to improve the antiviral potential of FLSC, we fused it with the hinge-CH2-CH3 region of human IgG1. The IgG moiety should increase both the affinity and stability in vivo of FLSC, due to the resultant bivalency and an extended serum half-life, thereby increasing its antiviral potency. We previously showed that (FLSC) IgG1 indeed had greater antiviral activity against T cell infections. Here we extend these results to macrophages, for which (FLSC) IgG1 has a more potent antiviral activity than FLSC alone, due in part to its higher binding affinity for CCR5. We also test both compounds in a relevant humanized mouse model and show that, as anticipated, the IgG1 moiety confers a greatly extended half-life. These data, taken together with previous results, suggest potential clinical utility for (FLSC) IgG1 and support further developmental work toward eventual clinical trials.

Background: Studies of patients failing second-line antiretroviral therapy (ART) in resource-limited settings (RLS) are few. Evidence suggests most patients who appear to be virologically failing do so not due to drug resistance but to poor adherence, which, if properly addressed, could allow continued use of less expensive first- and second-line regimens. Drug resistant mutations (DRMs) were characterized among patients virologically failing second-line ART in Rwanda., Methods: A total of 128 adult patients receiving second-line ART for at least 6 months were invited to participate; 74 agreed and had HIV-1 viral load (VL) measured. Resistance genotypes were conducted in patients with virological failure (VF; that is, VL ≥1,000 copies/ml)., Results: In total, 35 patients met the criteria for VF. The median time on lopinavir/ritonavir-based second-line ART was 2.7 years. Of 30 successful resistance genotype analyses, 13 (43%) had ≥1 nucleoside reverse transcriptase inhibitor (NRTI) mutation, 18 (60%) had at least 1 non-NRTI mutation and 5 (17%) had at least 1 major protease inhibitor mutation. Eleven (37%) had virus without significant mutations that would be fully sensitive to first-line ART; 12 (40%) had DRM to first-line ART but sensitive to second-line ART. Only 7 patients (23%) demonstrated a DRM profile requiring third-line ART., Conclusions: Among 30 genotyped samples of patients with VF on second-line ART, more than one-third had no significant DRMs, implicating poor adherence as the primary cause of VF. The majority of patients (77%) would not have required third-line ART. These findings reinforce the need for intensive adherence assessment and counselling for patients who appear to be failing second-line ART in RLS.

Background: Antiretroviral (ARV) drugs targeting retroviral enzymes have been extensively employed to treat HIV-1 infection. Drawbacks of this approach include cost, toxicity, and the eventual emergence of resistant strains that threaten prophylactic and/or therapeutic efficacy. Accordingly, efforts to develop next-generation ARV approaches are warranted, particularly if they can offer a higher threshold of resistance. We have previously shown that FLSC, a fusion protein containing gp120(BAL) and the D1 and D2 domains of human CD4, specifically binds CCR5, an important cellular co-receptor, and inhibits the entry of R5 HIV isolates. (FLSC) IgG1, a fusion of FLSC and the hinge-C(H)2-C(H)3 region of human IgG1, has an increased antiviral activity, likely due to the resultant bivalency., Methods: In this study, we show CCR5 reduction upon (FLSC) IgG1 treatment both by standard flow cytometry and visualized using a novel nanoparticle method. A β-lactamase virus-cell fusion assay was used to quantify (FLSC) IgG1 inhibition of HIV-1 entry into both cell lines and primary cells. Synergistic anti-viral activities of (FLSC) IgG1 and MVC in primary cells were evaluated by measuring supernatant p24 levels via ELISA and calculated using the MacSynergy™ II program., Results: We previously reported that treatment with the CCR5 small molecule antagonist Maraviroc (MVC) increased the apparent exposure of the (FLSC) IgG1 binding sites on CCR5, leading us to wonder if the two compounds used in combination might synergize in their anti-viral activity. Here we show that this is indeed the case. We demonstrate that fusion protein (FLSC) IgG1, strongly synergizes with the CCR5 antagonist Maraviroc to successfully inhibit both MVC-sensitive and MVC-resistant R5 HIV-1., Conclusion: Observed synergy between (FLSC) IgG1 and MVC was high in both, cell lines and primary PBMCs. This has relevance for future in vivo studies. In addition, synergy occurred both with MVC-sensitive viruses and MVC-resistant viruses, partially restoring the inhibitory effect of MVC. These findings suggest that a combinatorial treatment based on these two compounds has potential merit and that future in vivo studies are warranted.

Objective: The M184V mutation in the HIV-1 reverse transcriptase gene is frequent (>50%) in patients, both in resource-rich and resource-limited countries, conferring high-level resistance (>100-fold) to the cytosine analog reverse transcriptase inhibitors lamivudine and emtricitabine. The reverse transcriptase enzyme of M184V HIV-1 mutants has reduced processivity, resulting in reduced viral replication, particularly at low deoxynucleotide (dNTP) levels. We hypothesized that lowering intracellular dNTPs with resveratrol, a dietary supplement, could interfere with replication of M184V HIV-1 mutants., Design and Methods: Evaluation of the activity of resveratrol on infection of primary peripheral blood lymphocytes by wild-type and M184V mutant HIV-1. We assayed both molecular clones and primary isolates of HIV-1, containing M184V alone and in combination with other reverse transcriptase mutations. Viral infection was quantified by p24 ELISA and by quantitative real-time PCR analysis. Cell viability was measured by colorimetric 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assays., Results: In virus-infectivity assays, resveratrol did not inhibit replication of wild-type NL4-3 (resveratrol EC50 > 10 μmol/l), but it inhibited NL4-3 184V mutant (resveratrol EC50 = 5.8 μmol/l). These results were confirmed by real-time PCR analysis of early and late products of reverse transcription. Resveratrol inhibited molecular clones and primary isolates carrying M184V, alone or in combination with other reverse transcriptase mutations (resveratrol EC50 values ranging from 2.5 to 7.7 μmol/l)., Conclusions: Resveratrol inhibits HIV-1 strains carrying the M184V mutation in reverse transcriptase. We propose resveratrol as a potential adjuvant in HIV-1 therapy, particularly in resource-limited settings, to help control emtricitabine-resistant M184V HIV-1 mutants.

Objective: To determine mortality associated with a new cancer diagnosis in an urban, predominantly African-American, HIV-infected population., Design: Retrospective cohort study., Methods: All HIV-infected patients diagnosed with cancer between 1 January 2000 and 30 June 2010 were reviewed. Mortality was examined using Kaplan-Meier estimates and Cox proportional hazards models., Results: There were 470 cases of cancer among 447 patients. Patients were predominantly African-American (85%) and male (79%). Non-AIDS-defining cancers (NADCs, 69%) were more common than AIDS-defining cancers (ADCs, 31%). Cumulative cancer incidence increased significantly over the study period. The majority (55.9%) was taking antiretroviral therapy (ART) at cancer diagnosis or started afterward (26.9%); 17.2% never received ART. Stage 3 or 4 cancer was diagnosed in 67%. There were 226 deaths during 1096 person years of follow-up, yielding an overall mortality rate of 206 per 1000 person years. The cumulative mortality rate at 30 days, 1 year, and 2 years was 6.5, 32.2, and 41.4%, respectively. Mortality was similar between patients on ART whether they started before or after the cancer diagnosis but was higher in patients who never received ART. In patients with a known cause of death, 68% were related to progression of the underlying cancer., Conclusion: In a large cohort of urban, predominantly African-American patients with HIV and cancer, many patients presented with late-stage cancer. There was substantial 30-day and 2-year mortality, although ART had a significant mortality benefit. Deaths were most often caused by progression of cancer and not from another HIV-related or AIDS-related event.

Background: Although used globally, little data exist on the efficacy of nevirapine (NVP) used in combination with tenofovir (TDF)/emtricitabine or lamivudine (XTC), and no large randomized prospective control trials exists comparing this combination with efavirenz (EFV)/TDF/(XTC)., Methods: As part of the AIDSRelief program, a retrospective review of patient medical chart information along with a cross-sectional viral load, and adherence measurement was conducted between 2004 and 2009. An on-treatment analysis excluded patients who died, transferred out of care, or were lost to follow-up. A switch of antiretrovirals for any reason was considered a failure in the intent-to-treat analysis. Patients with only clinically relevant reasons for switching such as toxicity, adverse effects, viral failure or clinical/immunological failure, lost to follow-up, and death were considered failures as part of the modified-intent-to-treat analysis. Step-wise multiple regression analysis was used to identify variables that were associated with viral suppression., Results: A random sample of 3862 patients met criteria and were included in this analysis. In the on-treatment analysis, older age (P < 0.004) and baseline CD4 <100 cells per cubic millimeter (P < 0.021) were the most significant variables impacting viral load. Patients on TDF/XTC/EFV achieved higher rates of viral suppression compared with patients on TDF/XTC/NVP or azidothymidine (AZT)/lamivudine (3TC)/NVP., Conclusion: Our data show that patients on TDF/XTC/EFV had better outcomes than patients on TDF/XTC/NVP, AZT/3TC/EFV, or AZT/3TC/NVP. High rates of virologic suppression seen in patients on this regimen are consistent with previous studies and indicate the need to increase use of this regimen in HIV programs to promote sustainable viral suppression over time.

R5 HIV-1 strains resistant to the CCR5 antagonist Maraviroc (MVC) can use drug-bound CCR5. We demonstrate that MVC-resistant HIV-1 exhibits delayed kinetics of coreceptor engagement and fusion during drug-bound versus free CCR5 infection of cell lines. Antibodies directed against the second extracellular loop (ECL2) of CCR5 had greater antiviral activity against MVC-bound compared to MVC-free CCR5 infection. However, in PBMCs, only ECL2 CCR5 antibodies HGS004 and HGS101, but not 2D7, inhibited infection by MVC resistant HIV-1 more potently with MVC-bound than with free CCR5. In addition, HGS004 and HGS101, but not 2D7, restored the antiviral activity of MVC against resistant virus in PBMCs. In flow cytometric studies, CCR5 binding by the HGS mAbs, but not by 2D7, was increased when PBMCs were treated with MVC, suggesting MVC increases exposure of the relevant epitope. Thus, HGS004 and HGS101 have antiviral mechanisms distinct from 2D7 and could help overcome MVC resistance., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Purpose: The once-daily nucleoside reverse transcriptase inhibitor backbone of tenofovir and emtricitabine has been proven effective in combination with efavirenz and protease inhibitors in large clinical trials. This study evaluated tenofovir and emtricitabine in combination with nevirapine., Methods: Viral load was assessed at baseline, Day 3, and Day 7 in addition to Weeks 2, 4, 8, 12, 16, 24, 32, 40, 48, 60, 72, and 84 in 10 antiretroviral-naïve patients participating in an open-label clinical trial of tenofovir and emtricitabine once daily in combination with nevirapine twice daily., Results: All patients achieved viral decay with this combination. Two patients discontinued prior to virologic suppression, one with a viral load of 55 copies/mL. Virologic suppression (<50 copies/mL) was achieved by Week 24 in the remaining 8 patients. An undetectable viral load was maintained during > or =60 weeks follow-up., Conclusion: In this study of treatment-naïve patients, the combination of tenofovir and emtricitabine plus twice-daily nevirapine produced sustained viral load decay in patients including those with a high baseline viral load.

COL40263 was a pilot 48-week, open-label, multicenter study evaluating the efficacy and safety of once-daily coformulated abacavir/lamivudine/zidovudine plus tenofovir in ART-naive, HIV-infected subjects. We examined the patterns of resistance that were selected on-therapy through 48 weeks in subjects with virologic nonresponse (VF). A total of 123 antiretroviral-naive HIV-1-infected subjects with plasma HIV-1 RNA > or = 30,000copies/ml were enrolled. For subjects with confirmed VF (HIV-1 RNA > or = 400 copies/ml at week 24 or later), HIV population genotypic and phenotypic analysis was performed. Of the 123 enrolled subjects, 14 (11%) had confirmed plasma HIV-1 RNA > or = 400 copies/ml through week 48. Of these subjects, 3/14 had evidence of drug resistance at baseline: 2/14 had HIV with K103N, Y188F/H/L/Y, and/or T215A and 1/14 had reduced zidovudine susceptibility. At the last time point analyzed, 4/14 subjects had wild-type HIV, while 10/14 subjects had HIV with either thymidine analogue mutations (TAMS) alone (3/10), TAMS + M184V (4/10), M184V only (1/10), or K65R/K (2/10). Matched phenotype was obtained for 13/14 subjects and 8/13 (62%) subjects had reduced susceptibility to one or more study drugs: 2/13 tenofovir, 3/13 abacavir, 4/13 zidovudine, and 7/13 lamivudine. The resistance pattern in COL40263 subjects with VF differs significantly from that reported for tenofovir-containing triple-nucleoside regimens. TAMs were detected in the majority (7/10) of samples from subjects with VF who selected any resistance mutation. These data suggest that TAMs selection is a preferred resistance route of this combination, with zidovudine modulating the resistance pathway against selection for K65R.

Maraviroc, the only CCR5 antagonist HIV inhibitor currently approved, has potent antiviral activity in treatment-experienced individuals infected with CCR5-using HIV-1 (R5 HIV-1). However, recent data from the MOTIVATE trials indicate that R5 HIV-1 can develop resistance to Maraviroc, underscoring the need for additional CCR5 antagonists. The CCR5 antagonist aplaviroc (APL) is active against Maraviroc-resistant viral strains but its clinical development has ended because of dose-related toxicity. Here we demonstrate that reduction of CCR5 density (receptors/cell) with the immunomodulatory drug rapamycin (RAPA) enhances the antiviral activity of APL, allowing lower, non-toxic effective doses. In the presence of RAPA, the concentration of APL required for 90% inhibition of R5 HIV-1 in primary CD4 lymphocytes was reduced by as much as 25-fold. We conclude that low doses of RAPA may reduce the anti-HIV effective dose of APL-derivatives currently in development and thus minimize their potential toxicity. Combinations of RAPA and CCR5 antagonists could provide an effective means to control drug-resistant R5 HIV in patients, most notably those infected with Maraviroc-resistant viruses.

Vicriviroc (VCV) is a chemokine (C-C motif) receptor 5 (CCR5) antagonist with potent anti-HIV activity that currently is being evaluated in phase III clinical trials. In the present study, donor CCR5 density (CCR5 receptors/CD4 lymphocytes) inversely correlated with VCV antiviral activity (Spearman's correlation test; r = 0.746, P = 0.0034). Low doses of the transplant drug rapamycin (RAPA) reduced CCR5 density and enhanced VCV antiviral activity. In drug interaction studies, the RAPA/VCV combination had considerable antiviral synergy (combination indexes of 0.1-0.04) in both multicycle and single-cycle infection of lymphocytes. The synergy between RAPA and VCV translated into dose reduction indexes of 8- to 41-fold reductions for RAPA and 19- to 658-fold reductions for VCV. RAPA enhanced VCV antiviral activity against both B and non-B clade isolates, potently suppressing clade G viruses with reported reduced sensitivities to VCV and to the licensed CCR5 antagonist maraviroc. Importantly, RAPA reduction of CCR5 density in lymphocytes sensitized VCV-resistant strains to VCV, inhibiting virus production by approximately 90%. We further demonstrated the role of CCR5 density on VCV activity against resistant virus in donor lymphocytes and in cell lines expressing varying CCR5 densities. Together, these results suggest that low doses of RAPA may increase the durability of VCV-containing regimens in patients by enhancing VCV viral suppression, by allowing the use of lower doses of VCV with reduced potential for toxicity, and by controlling emerging VCV-resistant variants.

Background: The current goal of human immunodeficiency virus type 1 (HIV-1) therapy is to maximally suppress viral replication. Securing this goal requires new drugs and treatment classes. The chemokine receptor CCR5 provides an entry portal for HIV-1, and PRO 140 is a humanized monoclonal antibody that binds to CCR5 and potently inhibits CCR5-tropic (R5) HIV-1 in vitro., Methods: A randomized, double-blind, placebo-controlled, dose-escalating study was conducted in 39 individuals with HIV-1 RNA levels or =5000 copies/mL, CD4(+) cell counts > or =250 cells/microL, no antiretroviral therapy for 3 months, and only R5 HIV-1 detectable. Cohorts were randomized 3:10 to receive placebo or doses of PRO 140 of 0.5, 2, or 5 mg/kg. Subjects were monitored for 58 days for safety, antiviral effects, and serum concentrations of PRO 140., Results: PRO 140 was generally well tolerated and demonstrated potent, rapid, prolonged, and dose-dependent antiviral activity. Mean reductions in HIV-1 RNA level of 0.58 log(10), 1.20 log(10) (P= .0002) and 1.83 log(10) (P= .0001) were observed for the 0.5-, 2-, and 5-mg/kg dose groups, respectively. Reductions in mean viral load of > or =10-fold were observed within 4 days and persisted for 2-3 weeks after treatment., Conclusions: This trial established clear proof of concept for PRO 140 as a potent antiretroviral agent with extended activity after a single dose., Trial Registration: ISRCTN Register: ISRCTN45537485 .

Regimens containing abacavir (ABC), tenofovir (TDF), and lamivudine (3TC) have recently been demonstrated to have high failure rates. This poses a clinical dilemma of how to manage patients currently being treated with other regimens containing tenofovir/abacavir. We evaluated the outcomes of tenofovir/abacavir regimens in our clinical practice through a retrospective review of 2655 charts. Two hundred patients (7%) were on a tenofovir/abacavir-containing regimen. Fifty-nine patients met the criteria for analysis and were grouped into three groups: (1) antiretroviral naïve, (2) virally suppressed patients switched to TDF/ABC, and (3) patients with failure of their first antiretroviral regimen. Rates of viral suppression in the naïve, switch, and first-failure groups were 95%, 86%, and 46%, respectively. In the first-failure group, viral suppression was 66% without and 18% with a preexisting M184V. A composite analysis of the groups revealed a success rate of 86% when the regimen contained zidovudine (ZDV) and 62% when it did not. No K65R mutations were noted. These findings support continued caution in the use of TDF/ABC in combination. However, these data suggest that this combination may be successfully used in selected situations such as in combination with ZDV. In patients already virally suppressed on a TDF/ABC-containing regimen, considerations include continuing the regimen or adding zidovudine, in the attempt to protect against the development of a K65R mutation and/or virologic failure, versus changing a stable regimen.

The humoral response to human immunodeficiency virus (HIV) remains incompletely understood. In this report, we describe biased λ light chain use during the HIV Env glycoprotein (Env) response in HIV infection and vaccination. We examined HIV Env binding (and neutralization) in the context of light chain use in subjects with acute HIV infection, chronic HIV infection, and among HIV vaccinees. In all populations tested, there was a λ chain bias for HIV Env binding antibodies, compared with other HIV antigens (such as p24) or tetanus toxoid. In subjects with chronic HIV infection, a λ bias was noted for neutralization, with λ antibodies accounting for up to 90% of all neutralization activity observed. This is the first report of antibody function in a human infection being tied to light chain use. In HIV infection, antibodies expressing λ light chains tended to have longer CDRL3s, increased light chain contact with HIV Env, and less hypermutation in the heavy chain, compared with antibodies using the κ light chain. These data also support an evolutionary model for the understanding the various κ to λ light chain ratios observed across species and suggest that the λ light chain bias against HIV provides the host an advantage in developing a more efficient humoral response. [ABSTRACT FROM AUTHOR]