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OBJECTIVE: To evaluate the antiviral activity, safety, pharmacokinetics, and pharmacokinetics/pharmacodynamics of short-term monotherapy with tenofovir alafenamide (TAF), a next-generation tenofovir (TFV) prodrug. DESIGN: A phase 1b, randomized, partially blinded, active- and placebo-controlled, dose-ranging study. METHODS: Treatment-naive and experienced HIV-1-positive adults currently off antiretroviral therapy were randomized to receive 8, 25, or 40 mg TAF, 300 mg tenofovir disoproxil fumarate (TDF), or placebo, each once daily for 10 days. RESULTS: Thirty-eight subjects were enrolled. Baseline characteristics were similar across dose groups. Significant reductions in plasma HIV-1 RNA from baseline to day 11 were observed for all TAF dose groups compared with placebo (P < 0.01), with a median decrease of 1.08-1.73 log10 copies per milliliter, including a dose-response relationship for viral load decrease up to 25 mg. At steady state, 8, 25, and 40 mg TAF yielded mean TFV plasma exposures [area under the plasma concentration-time curve (AUCtau)] of 97%, 86%, and 79% lower, respectively, as compared with the TFV exposures observed with 300 mg TDF. For 25 and 40 mg TAF, the mean intracellular peripheral blood mononuclear cell tenofovir diphosphate AUCtau was ∼7-fold and ∼25-fold higher, relative to 300 mg TDF. CONCLUSIONS: Compared with 300 mg TDF, TAF demonstrated more potent antiviral activity, higher peripheral blood mononuclear cell intracellular tenofovir diphosphate levels, and lower plasma TFV exposures, at approximately 1/10th of the dose. This may translate into greater antiviral efficacy, a higher barrier to resistance, and an improved safety profile relative to TDF, supporting further investigation of TAF dosed once daily in HIV-infected patients.

Analysis of the HIV protease gene from the plasma of HIV-infected patients revealed substitutions at nine different codons selected in response to monotherapy with the protease inhibitor ritonavir. Mutants at valine-82, although insufficient to confer resistance, appeared first in most patients. Significant phenotypic resistance required multiple mutations in HIV protease, which emerged subsequently in an ordered, stepwise fashion. The appearance of resistance mutations was delayed in patients with higher plasma levels of ritonavir. Early mutants retained susceptibility to structurally diverse protease inhibitors, suggesting that dual protease inhibitor therapy might increase the duration of viral suppression.

Inhibitors of HIV-1 protease represent a new class of antiretroviral compounds. Here, we report the design and synthesis of two novel C2 symmetry-based inhibitors, MP-134 and MP-167, specifically targeted against HIV-1 variants with reduced sensitivity to another related protease inhibitor, A-77003. In addition, we describe the in vitro selection of viral variants with reduced sensitivity to these two protease inhibitors. An isoleucine-to-valine substitution at residue 84 (I84V) of the HIV-1 protease confers resistance to MP-134, whereas a glycine-to-valine substitution at residue 48 (G48V) confers resistance to MP-167. Testing other protease inhibitors against these variants has revealed specific overlapping patterns of resistance among these agents. These findings have important implications in the design of combination regimens using multiple protease inhibitors and underscore the need to develop non-cross-resistant compounds to be used toward this goal.

Treatment of infected patients with ABT-538, an inhibitor of the protease of human immunodeficiency virus type 1 (HIV-1), causes plasma HIV-1 levels to decrease exponentially (mean half-life, 2.1 +/- 0.4 days) and CD4 lymphocyte counts to rise substantially. Minimum estimates of HIV-1 production and clearance and of CD4 lymphocyte turnover indicate that replication of HIV-1 in vivo is continuous and highly productive, driving the rapid turnover of CD4 lymphocytes.

Given the limitations of antiretroviral therapy and recent advances in our understanding of HIV persistence during effective treatment, there is a growing recognition that a cure for HIV infection is both needed and feasible. The International AIDS Society convened a group of international experts to develop a scientific strategy for research towards an HIV cure. Several priorities for basic, translational and clinical research were identified. This Opinion article summarizes the group's recommended key goals for the international community.

Critical advances in the early diagnosis of HIV now allow for treatment opportunities during acute infection. It remains unclear whether treatment of acute HIV infection with antiretroviral therapy improves long-term clinical outcomes for the individual and current guidelines are not definitive in recommending therapy at this stage of infection. However, treatment of acute HIV infection may have short-term benefit on viral set point when compared to delayed therapy as well as reducing the risk of transmission to others. Herein we review the immunological and clinical literature to discuss whether we should treat acute HIV infection, both from the perspective of the individual HIV-infected patient and from the public health perspective. As transmission of drug-resistant HIV variants are of concern, we also review recent clinical trial data to provide recommendations for which specific antiretroviral treatment regimens should be considered for the treatment of acute HIV infection.

Transmitted drug resistance (TDR) is critical to managing HIV-1-infected individuals and being a public health concern. We report on TDR prevalence and include analyses of phylogenetic clustering of HIV-1 in a predominantly men who have sex with men cohort diagnosed during acute/recent HIV-1 infection in New York City.Genotypic resistance testing was conducted on plasma samples of 600 individuals with acute/recent HIV-1 infection (1995-2010). Sequences were used for resistance and phylogenetic analyses. Demographic and clinical data were abstracted from medical records. TDR was defined according to International AIDS Society-USA and Stanford HIV database guidelines. Phylogenetic and other analyses were conducted using PAUP*4.0 and SAS, respectively.The mean duration since HIV-1 infection was 66.5 days. TDR prevalence was 14.3% and stably ranged between 10.8% and 21.6% (P(trend) = 0.42). Nucleoside reverse transcriptase inhibitors resistance declined from 15.5% to 2.7% over the study period (P(trend) = 0.005). M41L (3.7%), T215Y (4.0%), and K103N/S (4.7%) were the most common mutations. K103N/S prevalence increased from 1.9% to 8.0% between 1995 and 2010 (P(trend) = 0.04). Using a rigorous definition of clustering, 19.3% (112 of 581) of subtype B viral sequences cosegregated into transmission clusters and clusters increased over time. There were fewer and smaller transmission clusters than had been reported in a similar cohort in Montreal but similar to reports from elsewhere.TDR is stable in this cohort and remains a significant concern to both individual patient management and the public health.

The role of antiretroviral therapy (ART) during acute and early human immunodeficiency virus type 1 (HIV-1) infection has been an area of investigation for several years; however, the benefits of such treatment remain unproved, and best practice for clinical management of this unique stage of infection remains unknown [1]. The initiation of ART shortly after HIV-1 infection has been shown to preserve HIV-1–specific immune responses that could improve virologic control on discontinuation of treatment [2–4]. However, prospective observational studies have evaluated the effects of early ART followed by treatment cessation on subsequent virologic control with conflicting results [5–15], and few randomized clinical trials have been performed in the setting of acute and early HIV-1 infection [16–20]. We hypothesized that 36 weeks of ART administered to participants within 6 months of acquiring HIV-1 infection would lower the virologic set point after treatment discontinuation. The AIDS Clinical Trials Group (ACTG) Setpoint Study (A5217) was a multicenter, randomized clinical trial during which individuals with recent but not acute HIV-1 infection were randomized to begin immediate treatment (IT) with a 36-week course of ART and then discontinue treatment, or to defer treatment (DT) until prespecified criteria for initiation of therapy were met. During a scheduled interim review, the Data and Safety Monitoring Board (DSMB) of the National Institute of Allergy and Infectious Diseases (NIAID) noted a higher than expected rate of disease progression and subsequent initiation of ART in the DT group, limiting the ability to compare the actual virologic set point between the 2 groups. As a result of these findings in June 2009, the DSMB stated that further enrollment and follow-up as designed could not be justified and recommended study discontinuation. We report here on the data collected through the time of the DSMB recommendations.

Here we have identified HIV-1 B clade Envelope (Env) amino acid signatures from early in infection that may be favored at transmission, as well as patterns of recurrent mutation in chronic infection that may reflect common pathways of immune evasion. To accomplish this, we compared thousands of sequences derived by single genome amplification from several hundred individuals that were sampled either early in infection or were chronically infected. Samples were divided at the outset into hypothesis-forming and validation sets, and we used phylogenetically corrected statistical strategies to identify signatures, systematically scanning all of Env. Signatures included single amino acids, glycosylation motifs, and multi-site patterns based on functional or structural groupings of amino acids. We identified signatures near the CCR5 co-receptor-binding region, near the CD4 binding site, and in the signal peptide and cytoplasmic domain, which may influence Env expression and processing. Two signatures patterns associated with transmission were particularly interesting. The first was the most statistically robust signature, located in position 12 in the signal peptide. The second was the loss of an N-linked glycosylation site at positions 413–415; the presence of this site has been recently found to be associated with escape from potent and broad neutralizing antibodies, consistent with enabling a common pathway for immune escape during chronic infection. Its recurrent loss in early infection suggests it may impact fitness at the time of transmission or during early viral expansion. The signature patterns we identified implicate Env expression levels in selection at viral transmission or in early expansion, and suggest that immune evasion patterns that recur in many individuals during chronic infection when antibodies are present can be selected against when the infection is being established prior to the adaptive immune response., Author Summary A single virus most often establishes HIV-1 infection. As a consequence, virus sampled early in infection is usually very homogeneous. A few months into the infection, the virus begins to accumulate mutations as it evolves to evade HIV-specific immune responses mounted by the infected host. During chronic infection, the viral population diversifies, reflecting the history of mutations that arose within that infected individual. We hypothesized that particular amino acids might confer a selective advantage during transmission or early infection, and others might recur during chronic infection because they provide common and effective strategies of immune escape. We compared a large number of viral sequences from several hundred infected people sampled soon after transmission or during chronic infection to identify such infection-status “signature” patterns. A particularly robust signature was identified in the signal peptide of Envelope, a region that regulates its expression. Other signatures were found in regions of Envelope that interact with its cellular receptors, or are implicated in immune escape.

Plasmacytoid DCs (pDCs) are innate immune cells that are specialized to produce IFN-α and to activate adaptive immune responses. Although IFN-α inhibits HIV-1 replication in vitro, the production of IFN-α by HIV-activated pDCs in vivo may contribute more to HIV pathogenesis than to protection. We have now shown that HIV-stimulated human pDCs allow for persistent IFN-α production upon repeated stimulation, express low levels of maturation molecules, and stimulate weak T cell responses. Persistent IFN-α production by HIV-stimulated pDCs correlated with increased levels of IRF7 and was dependent upon the autocrine IFN-α/β receptor feedback loop. Because it has been shown that early endosomal trafficking of TLR9 agonists causes strong activation of the IFN-α pathway but weak activation of the NF-κB pathway, we sought to investigate whether early endosomal trafficking of HIV, a TLR7 agonist, leads to the IFN-α-producing phenotype we observed. We demonstrated that HIV preferentially traffics to the early endosome in human pDCs and therefore skews pDCs toward a partially matured, persistently IFN-α-secreting phenotype.

Mutations that allow escape from CD8 T-cell responses are common in HIV-1 and may attenuate pathogenesis by reducing viral fitness. While this has been demonstrated for individual cases, a systematic investigation of the consequence of HLA class I-mediated selection on HIV-1 in vitro replication capacity (RC) has not been undertaken. We examined this question by generating recombinant viruses expressing plasma HIV-1 RNA-derived Gag-Protease sequences from 66 acute/early and 803 chronic untreated subtype B-infected individuals in an NL4-3 background and measuring their RCs using a green fluorescent protein (GFP) reporter CD4 T-cell assay. In acute/early infection, viruses derived from individuals expressing the protective alleles HLA-B*57, -B*5801, and/or -B*13 displayed significantly lower RCs than did viruses from individuals lacking these alleles ( P < 0.05). Furthermore, acute/early RC inversely correlated with the presence of HLA-B-associated Gag polymorphisms ( R = −0.27; P = 0.03), suggesting a cumulative effect of primary escape mutations on fitness during the first months of infection. At the chronic stage of infection, no strong correlations were observed between RC and protective HLA-B alleles or with the presence of HLA-B-associated polymorphisms restricted by protective alleles despite increased statistical power to detect these associations. However, RC correlated positively with the presence of known compensatory mutations in chronic viruses from B*57-expressing individuals harboring the Gag T242N mutation ( n = 50; R = 0.36; P = 0.01), suggesting that the rescue of fitness defects occurred through mutations at secondary sites. Additional mutations in Gag that may modulate the impact of the T242N mutation on RC were identified. A modest inverse correlation was observed between RC and CD4 cell count in chronic infection ( R = −0.17; P < 0.0001), suggesting that Gag-Protease RC could increase over the disease course. Notably, this association was stronger for individuals who expressed B*57, B*58, or B*13 ( R = −0.27; P = 0.004). Taken together, these data indicate that certain protective HLA alleles contribute to early defects in HIV-1 fitness through the selection of detrimental mutations in Gag; however, these effects wane as compensatory mutations accumulate in chronic infection. The long-term control of HIV-1 in some persons who express protective alleles suggests that early fitness hits may provide lasting benefits.

Human immunodeficiency virus type 1 (HIV-1) controllers maintain viremia at g ag-protease chimeric viruses constructed using the earliest postinfection samples displayed significantly lower replication capacities than isolates from persons who failed to control viremia ( P = 0.0003). Protective HLA class I alleles were not enriched in these early HIV controllers, but viral sequencing revealed a significantly higher prevalence of drug resistance mutations associated with impaired viral fitness in controllers than in noncontrollers (6/15 [40.0%] versus 10/80 [12.5%], P = 0.018). Moreover, of two HLA-B57-positive (B57 + ) controllers identified, both harbored, at the earliest time point tested, signature escape mutations within Gag that likewise impair viral replication capacity. Only five controllers did not express “protective” alleles or harbor viruses with drug resistance mutations; intriguingly, two of them displayed typical B57 signature mutations (T242N), suggesting the acquisition of attenuated viruses from B57 + donors. These data indicate that acute/early stage viruses from persons who become controllers have evidence of reduced replication capacity during the initial stages of infection which is likely associated with transmitted or acquired CTL escape mutations or transmitted drug resistance mutations. These data suggest that viral dynamics during acute infection have a major impact on HIV disease outcome.

Elucidating virus-host interactions responsible for HIV-1 transmission is important for advancing HIV-1 prevention strategies. To this end, single genome amplification (SGA) and sequencing of HIV-1 within the context of a model of random virus evolution has made possible for the first time an unambiguous identification of transmitted/founder viruses and a precise estimation of their numbers. Here, we applied this approach to HIV-1 env analyses in a cohort of acutely infected men who have sex with men (MSM) and found that a high proportion (10 of 28; 36%) had been productively infected by more than one virus. In subjects with multivariant transmission, the minimum number of transmitted viruses ranged from 2 to 10 with viral recombination leading to rapid and extensive genetic shuffling among virus lineages. A combined analysis of these results, together with recently published findings based on identical SGA methods in largely heterosexual (HSX) cohorts, revealed a significantly higher frequency of multivariant transmission in MSM than in HSX [19 of 50 subjects (38%) versus 34 of 175 subjects (19%); Fisher's exact p = 0.008]. To further evaluate the SGA strategy for identifying transmitted/founder viruses, we analyzed 239 overlapping 5′ and 3′ half genome or env-only sequences from plasma viral RNA (vRNA) and blood mononuclear cell DNA in an MSM subject who had a particularly well-documented virus exposure history 3–6 days before symptom onset and 14–17 days before peak plasma viremia (47,600,000 vRNA molecules/ml). All 239 sequences coalesced to a single transmitted/founder virus genome in a time frame consistent with the clinical history, and a molecular clone of this genome encoded replication competent virus in accord with model predictions. Higher multiplicity of HIV-1 infection in MSM compared with HSX is consistent with the demonstrably higher epidemiological risk of virus acquisition in MSM and could indicate a greater challenge for HIV-1 vaccines than previously recognized., Author Summary Understanding the biology of sexual transmission of HIV-1 could contribute importantly to the development of effective prevention measures. However, different routes of virus transmission (vaginal, rectal, penile or oral) and inaccessibility of tissues at or near the time of virus transmission make this goal elusive. Here, we apply single genome amplification and sequencing of plasma HIV-1 and a model of random virus evolution to a cohort of acutely infected men who have sex with men (MSM) and find that MSM are twice as likely as heterosexuals to become infected by multiple viruses as opposed to a single virus. Some MSM subjects were infected by as many as 7 to 10 or more genetically distinct viruses as a consequence of a single exposure event. We go on to molecularly clone the first full-length transmitted/founder subtype B HIV-1 virus and show that it is highly replicative in human CD4+ T-cells but not macrophages. Our study provides the first comparative, quantitative analysis of the multiplicity of HIV-1 infection in the two primary risk groups—MSM and heterosexuals—driving the global pandemic, and we discuss the implications of the findings to HIV-1 vaccine development and prevention research.

Acute human immunodeficiency virus type 1 (HIV-1) infection is characterized by high levels of immune activation. Immunomodulation with cyclosporine combined with antiretroviral therapy (ART) in the setting of acute and early HIV-1 infection has been reported to result in enhanced immune reconstitution. Fifty-four individuals with acute and early infection were randomized to receive ART with 4 weeks of cyclosporine versus ART alone. In 48 subjects who completed the study, there were no significant differences between treatment arms in levels of proviral DNA or CD4(+) T cell counts. Adjunctive therapy with cyclosporine in this setting does not provide apparent virologic or immunologic benefit.

Background We conducted a Phase I dose escalation trial of ADVAX, a DNA-based candidate HIV-1 vaccine expressing Clade C/B' env, gag, pol, nef, and tat genes. Sequences were derived from a prevalent circulating recombinant form in Yunnan, China, an area of high HIV-1 incidence. The objective was to evaluate the safety and immunogenicity of ADVAX in human volunteers. Methodology/Principal Findings ADVAX or placebo was administered intramuscularly at months 0, 1 and 3 to 45 healthy volunteers not at high risk for HIV-1. Three dosage levels [0.2 mg (low), 1.0 mg (mid), and 4.0 mg (high)] were tested. Twelve volunteers in each dosage group were assigned to receive ADVAX and three to receive placebo in a double-blind design. Subjects were followed for local and systemic reactogenicity, adverse events, and clinical laboratory parameters. Study follow up was 18 months. Humoral immunogenicity was evaluated by anti-gp120 binding ELISA. Cellular immunogenicity was assessed by a validated IFNγ ELISpot assay and intracellular cytokine staining. ADVAX was safe and well-tolerated, with no vaccine-related serious adverse events. Local and systemic reactogenicity events were reported by 64% and 42% of vaccine recipients, respectively. The majority of events were mild. The IFNγ ELISpot response rates to any HIV antigen were 0/9 (0%) in the placebo group, 3/12 (25%) in the low-dosage group, 4/12 (33%) in the mid-dosage group, and 2/12 (17%) in the high-dosage group. Overall, responses were generally transient and occurred to each gene product, although volunteers responded to single antigens only. Binding antibodies to gp120 were not detected in any volunteers, and HIV seroconversion did not occur. Conclusions/Significance ADVAX delivered intramuscularly is safe, well-tolerated, and elicits modest but transient cellular immune responses. Trial Registration Clinicaltrials.gov NCT00249106

Background Immunological characterization of acute/early HIV-1 infection is important for the design of effective vaccine capable of neutralizing early transmitted virus. However, while recently there is significant progress in our understanding of the nature of such virus, our knowledge of the antibodies elicited during this period and their dynamics is scarce. In particular, there are no such well characterized human monoclonal antibodies (mAbs).

Background We have recently shown that transmitted/founder virus(es) can be identified unambiguously using single genome amplification (SGA) (Keele, PNAS, 2008; Salazar, JEM, 2009) and that in heterosexual transmissions approximately 80% of patients are infected by a single virus or infected cell (Keele, PNAS, 2008; Haaland, PLoS Pathogens, 2009; Abrahams, JVirol, 2009). Here we explore the characteristics of virus transmission in men who have sex with men (MSM) and injection drug users (IDU).

We evaluated the human immunodeficiency virus type 1 (HIV-1) integrase coding region of thepolgene for the presence of natural polymorphisms in patients during early infection (AHI) and with triple-class drug-resistant HIV-1 (MDR). We analyzed selected recombinant viruses containing patient-derived HIV-1 integrase for susceptibility to a panel of strand transfer integrase inhibitors (InSTI). A pretreatment sequence analysis of the integrase coding region was performed for 112 patients identified during acute or early infection and 15 patients with triple-class resistance. A phenotypic analysis was done on 10 recombinant viruses derived from nine patients against a panel of six diverse InSTI. Few of the polymorphisms associated with in vitro InSTI resistance were identified in the samples from newly infected individuals or those patients with MDR HIV-1. We identified polymorphisms V72I, L74I, T97A, V151I, M154I/L, E157Q, V165I, V201I, I203M, T206S, and S230N. V72I was the most common, seen in 63 (56.3%) of the AHI samples. E157Q was the only naturally occurring mutation thought to contribute to resistance to elvitegravir, raltegravir, and L-870,810. None of the patient-derived viruses demonstrated any significant decrease in susceptibility to the drugs tested. In summary, the integrase coding region contains as much natural variation as that seen in protease, but mutations associated with high-level resistance to existing InSTI are rarely, if ever, present in integrase naïve patients, especially those being used clinically. Most of the highly prevalent polymorphisms have little effect on InSTI susceptibility in the absence of specific primary mutations. Baseline testing for integrase susceptibility in InSTI-naïve patients is not currently warranted.

Background: Little is known about modifications to highly active antiretroviral therapy (HAART) initiated during acute or early HIV infection. Methods: Reasons for first modifications of HAART regimens were recorded using the AIDS Clinical Trials Group form among 363 subjects who initiated HAART within 1 year of seroconversion from 2005 in the Acute Infection and Early Disease Research Program. Modifications recorded as due to "patient choice" or "physician choice" were clarified by query to the recording site. Times to events were analyzed by Kaplan-Meier methods; significance of differences was assessed by the log-rank test. Results: Two hundred five of 363 (56%) subjects modified therapy, at a median of 425 days after initiation, by changing drugs, discontinuing treatment, or removing or adding drugs. Most modifications were attributed to toxicity (n = 105, 51%), most of which was low grade; regimen simplification (n = 18, 5%); and achievement of viral suppression (n = 15, 7%). Time to first modification was shorter for those with shorter time from infection to initiation (P = 0.005) and those having higher CD4 lymphocyte count at initiation (P = 0.06). Modifications occurred sooner in subjects receiving regimens taken more than once daily (P < 0.001) or with more than 2 pills daily (P < 0.001). Most regimens were nonnucleoside reverse transcriptase inhibitor based or protease inhibitor based, and these did not differ significantly in rate and timing of modification. Conclusions: HAART initiated early in HIV infection was modified in the majority of cases, usually due to minor toxicities whose incidence was similar for protease inhibitor-based and nonnucleoside reverse transcriptase inhibitor-based regimens. Convenience of regimens (lower pill burden and dosing frequency) was associated with a lower rate of modification.

In the developed world, access to highly active antiretroviral therapy (HAART) has led to significant reductions in the morbidity and mortality attributed to HIV/AIDS. However, the continual emergence of HIV-1 strains resistant to currently available classes of antiretrovirals highlights the need to develop agents with novel mechanisms of action. Successful completion of the HIV-1 viral life cycle depends in part on the integration of complementary DNA mediated by the enzyme HIV-1 integrase, one of three essential enzymes encoded in the viral genome. The integrase inhibitors have demonstrated the ability to act specifically at the strand transfer step during integration, making HIV-1 integrase a valid and attractive chemotherapeutic target for the treatment of HIV/AIDS. In clinical trials, raltegravir has been shown to be a potent drug with a pharmacokinetic profile that supports a twice-daily dosing schedule. In addition, it has demonstrated a favorable side-effect profile in treatment-naive and -experienced patients and a subset of heavy treatment-experienced patients have been able a achieve virologic suppression with raltegravir as part of combination therapy despite limited treatment options. In October 2007, raltegravir was approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV-1 as part of combination antiretroviral therapy in treatment-experienced patients-providing an additional option for the management of the HIV-1 infected individual.

Three neutralizing monoclonal antibodies (MAbs), 2G12, 2F5, and 4E10, with activity in vitro and in vivo were administered in an open-label, nonrandomized, proof-of-concept study to attempt to prevent viral rebound after interruption of antiretroviral therapy (ART). Ten human immunodeficiency virus type 1-infected individuals identified and treated with ART during acute and early infection were enrolled. The first six patients were administered 1.0 g of each of the three MAbs per infusion. The remaining four patients received 2G12 at 1.0 g/infusion and 2.0 g/infusion of 2F5 and 4E10. The MAbs were well tolerated. Grade I post-partial thromboplastin time prolongations were noted. Viral rebound was observed in 8/10 subjects (28 to 73 days post-ART interruption), and 2/10 subjects remained aviremic over the course of the study. In seven of eight subjects with viral rebound, clear resistance to 2G12 emerged, whereas reductions in the susceptibilities of plasma-derived recombinant viruses to 2F5 and 4E10 were neither sustained nor consistently measured. Viral rebound was associated with a preferential depletion of CD4 + T cells within the gastrointestinal tract. Though safe, the use of MAbs generally delayed, but did not prevent, virologic rebound. Consideration should be given to further pilot studies with alternative combinations of MAbs and perhaps additional novel treatment modalities.

The continuing, randomised, multinational, phase IIB POWER 1 and 2 studies aim to evaluate efficacy and safety of darunavir in combination with low-dose ritonavir in treatment-experienced HIV-1-infected patients. We did a pooled subgroup analysis to update results at week 48 for patients receiving the recommended dose of darunavir-ritonavir compared with those receiving other protease inhibitors (PIs).After 24-week dose-finding phases and primary efficacy analyses, patients randomised to receive darunavir-ritonavir were given 600/100 mg twice daily, and patients receiving control PIs continued on assigned treatment into the longer-term, open-label phase; all patients continued on optimised background regimen. We assessed patients who had reached week 48 or discontinued earlier at the time of analysis; for the darunavir-ritonavir group, only patients who received 600/100 mg twice daily from baseline were included. Analyses were intention-to-treat. The POWER 2 study (TMC114-C202) is registered with ClinicalTrials.gov (NCT00071097).At week 48, 67 of 110 (61%) darunavir-ritonavir patients compared with 18 of 120 (15%) of control PI patients had viral load reductions of 1 log10 copies per mL or greater from baseline (primary endpoint; difference in response rates 46%, 95% CI 35%-57%, p0.0001). Based on a logistic regression model including stratification factors (baseline number of primary PI mutations, use of enfuvirtide, baseline viral load) and study as covariates, the difference in response was 50% (odds ratio 11.72, 95% CI 5.75-23.89). In the darunavir-ritonavir group, rates of adverse events were mostly lower than or similar to those in the control group when corrected for treatment exposure. No unexpected safety concerns were identified.Efficacy responses with darunavir-ritonavir 600/100 mg twice daily plus optimised background regimen were greater than those with control PI and were sustained to at least week 48, with favourable safety and tolerability in treatment-experienced patients. This regimen could expand the treatment options available for such patients.

BACKGROUND: During acute and early HIV-1 infection (AEI), up to 60% of CD4(+) T cells in the lamina propria of the lower gastrointestinal (GI) tract are lost as early as 2-4 wk after infection. Reconstitution in the peripheral blood during therapy with highly active antiretroviral therapy (HAART) is well established. However, the extent of immune reconstitution in the GI tract is unknown. METHODS AND FINDINGS: Fifty-four AEI patients and 18 uninfected control participants underwent colonic biopsy. Forty of the 54 AEI patients were followed after initiation of antiretroviral therapy (18 were studied longitudinally with sequential biopsies over a 3-y period after beginning HAART, and 22 were studied cross sectionally after 1-7 y of uninterrupted therapy). Lymphocyte subsets, markers of immune activation and memory in the peripheral blood and GI tract were determined by flow cytometry and immunohistochemistry. In situ hybridization was performed in order to identify persistent HIV-1 RNA expression. Of the patients studied, 70% maintained, on average, a 50%-60% depletion of lamina propria lymphocytes despite 1-7 y of HAART. Lymphocytes expressing CCR5 and both CCR5 and CXCR4 were persistently and preferentially depleted. Levels of immune activation in the memory cell population, CD45RO+ HLA-DR+, returned to levels seen in the uninfected control participants in the peripheral blood, but were elevated in the GI tract of patients with persistent CD4+ T cell depletion despite therapy. Rare HIV-1 RNA-expressing cells were detected by in situ hybridization. CONCLUSIONS: Apparently suppressive treatment with HAART during acute and early infection does not lead to complete immune reconstitution in the GI mucosa in the majority of patients studied, despite immune reconstitution in the peripheral blood. Though the mechanism remains obscure, the data suggest that there is either viral or immune-mediated accelerated T cell destruction or, possibly, alterations in T cell homing to the GI tract. Although clinically silent over the short term, the long-term consequences of the persistence of this lesion may emerge as the HIV-1-infected population survives longer owing to the benefits of HAART.

We sought to determine whether pretreatment low pol replication capacity (polRC) is associated with CD4 T-cell count gains during antiretroviral therapy (ART). Patients were recruited at north American and Australian sites. Viral po/RC was measured before starting ART in all subjects. We examined 243 individuals for a median 260 days after initiating ART. Low baseline polRC was associated with greater CD4 T-cell gains independent of virological responses.

The increasing prevalence of transmitted drug-resistant HIV-1 has highlighted the challenging issue of the optimal management of antiretroviral-naïve, newly infected patients with multidrug-resistant HIV-1. This review discusses current trends in the evolution and transmission of HIV-1 with reduced susceptibility to multiple antiretroviral agents. In most cases, clinical strategies for the management of such patients with stable virological and immunological parameters involve deferment of therapy until clinically indicated. When a decision is made to initiate therapy, the process of selecting a regimen should consider baseline viral genotype and phenotype results, as well as the inclusion of novel agents with diverse mechanisms of action, in order to achieve a more complete suppression of viral replication. A summary of established and investigational antiretroviral agents is presented in this review, together with novel therapeutic approaches to decrease the burden of viral replication and maintain immunological status in cases of transmitted multidrug-resistant HIV-1 infection.

The effective management of HIV-1 infection has evolved dramatically over the past decade. As treatments have become more effective, better tolerated, and easier to take, treatment success as defined by surrogate markers has become increasingly common. Nevertheless, responses to therapy are not uniform, and even in the ideal setting of clinical trials with a select patient population treated with a compact and well-tolerated regimen, up to 20% of patients will fail to achieve sustained antiviral responses. The factors that are predictors of response to antiretroviral therapy, including adherence, stage of disease at baseline, treatment history, and demographic factors, are discussed.

Transmitted resistance to antiretroviral drugs in acute and early HIV-1 infection has been well documented, although overall trends vary depending on geography and cohort characteristics. To describe the changing pattern of transmitted drug-resistant HIV-1 in a well-defined cohort in New York City, a total of 361 patients with acute or recent HIV-1 infection were prospectively studied over a decade (1995-2004) with respect to HIV-1 genotypes and longitudinal T-cell subsets and HIV-1 RNA levels. The prevalence of overall transmitted resistance changed from 13.2% to 24.1% (P = 0.11) during the periods 1995 to 1998 and 2003 to 2004. Nonnucleoside reverse transcriptase inhibitor resistance prevalence increased significantly from 2.6% to 13.4% (P = 0.007) during the same periods, whereas prevalence of multidrug-resistant virus shifted from 2.6% to 9.8% (P = 0.07) but did not achieve statistical significance. A comparable immunologic and virologic response of appropriately treated individuals was observed regardless of viral drug susceptibility status, suggesting that initial combination therapy guided by baseline resistance testing in the case of acute and early infection may result in a favorable treatment response even in the case of a drug-resistant virus. These data have important implications for selection of empiric first-line regimens for treatment of acutely infected antiretroviral-naive individuals and reinforce the need for baseline resistance testing in acute and early HIV-1 infection.

It has become evident that the gastrointestinal tract is preferentially and profoundly depleted of CD4+ T cells during acute HIV-1 infection. The enhanced susceptibility of gastrointestinal lymphoid tissue to HIV-1 is in part due to the large complement of CCR5+ memory CD4+ T cells resident at this site. Here we summarize the recent findings demonstrating that the gastrointestinal tract plays a critical role in the pathogenesis of acute HIV-1 and simian immunodeficiency virus infections. Ongoing work in this field is likely to have a significant effect on HIV research in the near future.

Summary Background Rapid progression to AIDS after acute HIV-1 infection, though uncommon, has been noted, as has the transmission of multidrug resistant viruses. Here, we describe a patient in whom these two factors arose concomitantly and assess the effects. Methods We did a case study of a patient with HIV-1 seroconversion. We genotyped the virus and host genetic markers by PCR and nucleotide sequencing. To ascertain the drug susceptibility of our patient's HIV-1 we did phenotypic studies with the PhenoSense assay. We assessed viral coreceptor use via syncytium formation in vitro and with a modified PhenoSense assay. Findings Our patient seems to have been recently infected by a viral variant of HIV-1 resistant to multiple classes of antiretroviral drugs. Furthermore, his virus population is dual tropic for cells that express CCR5 or CXCR4 coreceptor. The infection has resulted in progression to symptomatic AIDS in 4–20 months. Interpretation The intersection of multidrug resistance and rapid development of AIDS in this patient is of concern, especially in view of his case history, which includes high-risk sexual contacts and use of metamfetamine. The public health ramifications of such a case are great.

As the AIDS epidemic continues unabated, the development of a human immunodeficiency virus (HIV) vaccine is critical. Ideally, an effective vaccine should elicit cell-mediated and neutralizing humoral immune responses. We have determined the in vitro susceptibility profile of sexually transmitted viruses from 91 patients with acute and early HIV-1 infection to three monoclonal antibodies, 2G12, 2F5, and 4E10. Using a recombinant virus assay to measure neutralization, we found all transmitted viruses were neutralized by 4E10, 80% were neutralized by 2F5, and only 37% were neutralized by 2G12. We propose that the induction of 4E10-like antibodies should be a priority in designing immunogens to prevent HIV-1 infection.

Given its population of CCR5-expressing, immunologically activated CD4+ T cells, the gastrointestinal (GI) mucosa is uniquely susceptible to human immunodeficiency virus (HIV)-1 infection. We undertook this study to assess whether a preferential depletion of mucosal CD4+ T cells would be observed in HIV-1–infected subjects during the primary infection period, to examine the anatomic subcompartment from which these cells are depleted, and to examine whether suppressive highly active antiretroviral therapy could result in complete immune reconstitution in the mucosal compartment. Our results demonstrate that a significant and preferential depletion of mucosal CD4+ T cells compared with peripheral blood CD4+ T cells is seen during primary HIV-1 infection. CD4+ T cell loss predominated in the effector subcompartment of the GI mucosa, in distinction to the inductive compartment, where HIV-1 RNA was present. Cross-sectional analysis of a cohort of primary HIV-1 infection subjects showed that although chronic suppression of HIV-1 permits near-complete immune recovery of the peripheral blood CD4+ T cell population, a significantly greater CD4+ T cell loss remains in the GI mucosa, despite up to 5 yr of fully suppressive therapy. Given the importance of the mucosal compartment in HIV-1 pathogenesis, further study to elucidate the significance of the changes observed here is critical.

We analyse viral load data of five patients under ritonavir monotherapy using a model of HIV dynamics under antiretroviral therapy that includes both drug pharmacokinetics and the intracellular delay from the time of cell infection to viral production. Using this approach we separate pharamacokinetic from intracellular delays, and obtain new estimates of intracellular delay and the antiviral efficacy of ritonavir. We find the average intracellular delay to be 1 day, in agreement with experiments. The average viral generation time is now estimated at 2 days, resulting in approximately 180 replication cycles per year. The model also reveals that ritonavir monotherapy is approximately 65% as efficacious as a recently used potent four-drug therapy, suggesting that selection for drug resistance may be facilitated by the relatively low efficacy of individual drugs, contributing in part to the inherent limitations of current therapies in combating HIV-1 infection.

HIV-1 infected patients after being treated with potent combinations of antiretroviral drugs for 2–6 months typically reach a state in which virus can no longer be detected within their blood. These patients with undetectable virus occasionally have viral load measurements that are above the limit of detection of current assays. Such measurements are called blips. Here we examine the possibility that such blips represent infrequent measurements taken during a period of time in which there is a transient elevation of virus in the patient’s blood, i.e., a so-called transient episode of viremia. By analyzing time series of blips from a large number of patients, we conclude that transient episodes of viremia exist and that on average they extend for a period of about 3 weeks.

Since the introduction of highly active antiretroviral therapy (HAART), there has been a dramatic decrease in human immunodeficiency virus (HIV)-related mortality. In diverse cohorts, most HAART-treated patients attain “undetectable” levels of plasma viral RNA ( 400 copies/ml were three times more likely to experience sustained viral rebound and to have impaired CD4 cell rises relative to those that maintained undetectable viral loads (VLs

Human immunodeficiency virus type 1 (HIV-1) infected patients treated with combination antiretroviral therapy frequently have the level of HIV-1 RNA detectable in plasma driven below the lower limit of detection of current assays, 50 copies ml(-1). Patients may continue to exhibit viral loads (VLs) below the assay limit for years, yet on some occasions the VL may be above the limit of detection. Whether these 'blips' in VL are simply assay errors or are indicative of intermittent episodes of increased viral replication is of great clinical concern. By analyzing the occurrence of viral blips in 123 treated HIV-infected patients, we show that patients do not share a common probability distribution of blip amplitude and thus reject the hypothesis that blips are solely due to assay variation.

Mathematical models provide an understanding of in vivo replication kinetics of human immunodeficiency virus type 1 (HIV-1). With a novel intervention designed for increased potency, we have more accurately deduced the half-lives of virus-producing CD4 + T cells, 0.7 day, and the generation time of HIV-1 in vivo, approximately 2 days, confirming the dynamic nature of HIV-1 replication.

Highly active antiretroviral therapy (HAART), administered to a HAART-naïve patient, perturbs the steady state of chronic infection. This perturbation provides an opportunity to investigate the existence and dynamics of different sources of viral production. Models of HIV dynamics can be used to make a comparative analysis of the efficacies of different drug regimens. When HAART is administered for long periods of time, most patients achieve 'undetectable' viral loads (VLs), i.e., below 50 copies/ml. Use of an ultrasensitive VL assay demonstrates that some of these patients obtain a low steady state VL in the range 5-50 copies/ml, while others continue to exhibit VL declines to below 5 copies/ml. Interestingly, when patients exhibit continued declines below 50 copies/ml the virus has a half-life of approximately 6 months, consistent with some estimates of the rate of latent cell decline. Some patients, despite having sustained undetectable VLs, show periods of transient viremia (blips). We present a statistical characterization of the blips observed in a set of 123 patients, suggesting that patients have different tendencies to show blips during the period of VL suppression, that intermittent episodes of viremia have common amplitude profiles, and that VL decay from the peak of a blip may have two phases.

Despite the clinical benefits of combination antiviral therapy, whether maximal antiviral potency has been achieved with current drug combinations remains unclear. We studied the first phase of decay of human immunodeficiency virus type 1 (HIV-1) RNA in plasma, one early indicator of antiviral activity, after the administration of a novel combination of lopinavir/ritonavir, efavirenz, tenofovir disoproxil fumarate, and lamivudine and compared it with that observed in matched cohorts treated with alternative combination regimens. On the basis of these comparisons, we conclude that the relative potency of highly active antiretroviral therapy may be augmented by as much as 25%-30%. However, it is important to emphasize that further study is warranted to explore whether these early measurements of relative efficacy provide long-term virologic and clinical benefits. Nevertheless, we believe that optimal treatment regimens for HIV-1 have yet to be identified and that continued research to achieve this goal is warranted.

Objective To assess temporal changes in prevalence of transmitted HIV-1 drug resistance in a homogeneous cohort of newly infected individuals. Methods Pretreatment genotypic and phenotypic drug resistance was tested in 154 subjects with primary HIV-1 infection identified between 1995 and 2001 (group A; n = 76) and 1999 and 2001 (group B; n = 78). Sequence analysis was assessed by population-based sequencing. Virus susceptibility to antiretroviral agents was determined by the PhenoSense assay (ViroLogic). Results The frequency of resistance-associated mutations in protease (PR) and reverse transcriptase (RT) genes increased from 13.2% (1995–1998) to 19.7% (1999–2001). Although the overall prevalence of viruses with phenotypic resistance did not vary (1995–1998, 10.0%; 1999–2001, 10.8%), the distribution of drug classes changed [nucleoside RT inhibitor (NRTI): 8.3% to 2.7%; non-NRTI: 5.0% to 8.1%; protease inhibitors (PI): 1.7% to 5.4%]. The decrease of phenotypic resistance to NRTI in 1999–2001 was caused by the absence of transmitted lamivudine-resistant variants. Phenotypically susceptible variants with aspartic acid or serine residues at position 215 of RT (5.3%;P = 0.04) instead emerged. Hypersusceptibility to PI decreased from 18.3% to 5.4% (P = 0.02) while the amino acid substitutions in PR increased over time: M36I (6.6% to 19.7%) and A71V/T (3.9% to 15.8%). Conclusions There was an increase in the number of HIV-1 variants with both genotypic and phenotypic resistance to non-NRTI and PI over time. Furthermore, viruses with altered genotypes compatible with thymidine analogue or PI exposure but susceptible phenotypes were seen in 1999–2001. The latter findings suggest transmission of viruses from subjects who have either changed or discontinued therapy.

Highly active antiretroviral therapy (HAART) has reduced the morbidity and mortality related to infection with the human immunodeficiency virus-1 (HIV-1) through its ability to suppress viral replication and preserve and reconstitute specific immune responses in many infected individuals. However, the complete eradication of HIV-1 with current HAART regimens is not considered possible by most experts. Moreover, many current antivirals have metabolic complications and limiting side effects. Consequently, the treatment paradigm has shifted from 'hit hard and early' to delaying the initiation of therapy until later in the course of HIV-1-related disease, with corresponding modifications of consensus treatment guidelines. Factors that need to be considered in deciding when to initiate therapy and with what regimen include the patient's risk of disease progression, the possible adverse drug effects, the patient's ability to adhere to the prescribed therapy, and the need to preserve future therapeutic options. In this article, we discuss the issues surrounding the initiation of HAART, and describe the virologic and immunologic milestones that may be achieved with effective antiretroviral therapy.

In order to boost immune responses in persons in whom highly active antiretroviral therapy (HAART) was initiated within 120 days of the onset of symptoms of newly acquired human immunodeficiency virus type 1 (HIV-1) infection, we administered vaccines containing a canarypox virus vector, vCP1452, with HIV-1 genes encoding multiple HIV-1 proteins, and recombinant gp160. Fifteen HIV-1-infected subjects who achieved sustained suppression of plasma viremia for at least 2 years were enrolled. While continuing antiretroviral therapy, each subject received at least four intramuscular injections of the vaccines on days 0, 30, 90, and 180. Adverse events were mild, with the most common being transient tenderness at the vCP1452 injection site. Of the 14 patients who completed vaccination, 13 had significant increases in anti-gp120 or anti-p24 antibody titers, and 9 had transient augmentation of their T-cell proliferation responses to gp160 and/or p24. HIV-1-specific CD8 + T cells were quantified using an intracellular gamma interferon staining assay. Among 11 patients who had increased CD8 + T-cell responses, seven had responses to more than one HIV-1 antigen. In summary, vaccination with vCP1452 and recombinant gp160 appears safe and immunogenic in newly HIV-1-infected patients on HAART.

We calculated the relative efficacy of treatment, defined as the rate of decline of virus levels in plasma during treatment relative to the rate of decline during highly potent combination therapy, in human immunodeficiency virus type 1 (HIV-1) patients treated for 56 days with different doses of the protease inhibitor nelfinavir. Relative efficacies based on the rate of decline of HIV-1 RNA levels in plasma over the first 14 to 21 days correlated with drug dose and viral load reduction by day 56. Calculation of relative treatment efficacies over the first 2 to 3 weeks of treatment can allow rapid assessment of new antiretroviral agents and dosing regimens, reducing the need to keep subjects in clinical trials on monotherapy for prolonged periods of time. Relative efficacy may also serve as a measure of treatment efficacy in patients in initiating established therapies.

Objectives: We evaluated virologic and immunologic responses to antiretroviral therapy in gut-associated lymphoid tissue (GALT) compared with those found in peripheral blood. Methods: Eight HIV-1-infected individuals were treated with three reverse transcriptase inhibitors and one protease inhibitor. Endoscopic biopsies were performed at baseline, and at months 1, 2, and 6. We measured the level of cell-associated multiply spliced and unspliced HIV-1 mRNA in GALT and in peripheral blood mononuclear cells. Immunologic responses were assessed by flow cytometry. Results: Levels of multiply spliced HIV-I mRNA declined in parallel fashion both in peripheral blood and GALT. After 6 months of therapy, unspliced HIV-1 mRNA in the GALT was below assay detection although it persisted in peripheral blood mononuclear cells in 4 study subjects. Although the percentage of CD4 + lymphocytes increased significantly in peripheral blood, only modest increases occurred in GALT. The percentage of activated CD8 + T cells decreased significantly in peripheral blood whereas only modest reductions occurred in GALT. Conclusions: Antiretroviral therapy effectively suppressed HIV-1 replication in GALT. The percentage of CD4 + T cells in peripheral blood uniformly increased in all study subjects, whereas it was more variable in the GALT.

Forty-seven patients presenting with primary human immunodeficiency virus (HIV) infection were treated with zidovudine 200 mg 3 times a day, lamivudine 150 mg 2 times a day, and indinavir 800 mg 3 times a day for 1 year. From a mean pretreatment viral RNA level of 4.93 log(10) copies/mL, the proportions of patients having

We have analyzed factors that might influence the in vitro quantitation of the T-proliferative response to HIV-1 Gag antigens, a common and increasingly used clinical measurement of helper T cell function in the context of HIV-1 infection. We have compared the rate and extent of T cell proliferation in freshly prepared and previously frozen PBMC samples, and have concluded that frozen cells can be used successfully; we have assessed whether the suppression of any HIV-1 replication in the PBMC cultures affects the extent of T cell proliferation; we have studied which forms of the Gag antigens are the most efficient at inducing T cell proliferation. From the latter experiments, we conclude that Gag proteins that include p17, and perhaps also p7, sequences flanking the central p24 capsid protein, are better stimulants than proteins that comprise only p24 sequences.

Replication-competent HIV-1 can be isolated from infected patients despite prolonged plasma virus suppression by anti-retroviral treatment1,2,3. Recent studies have identified resting, memory CD4+ T lymphocytes as a long-lived latent reservoir of HIV-1 (refs. 4,5). Cross-sectional analyses indicate that the reservoir is rather small, between 103 and 107 cells per patient5,6. In individuals whose plasma viremia levels are well suppressed by anti-retroviral therapy, peripheral blood mononuclear cells containing replication-competent HIV-1 were found to decay with a mean half-life of approximately 6 months7, close to the decay characteristics of memory lymphocytes in humans and monkeys8,9,10. In contrast, little decay was found in a less-selective patient population11. We undertook this study to address this apparent discrepancy. Using a quantitative micro-culture assay, we demonstrate here that the latent reservoir decays with a mean half-life of 6.3 months in patients who consistently maintain plasma HIV-1 RNA levels of fewer than 50 copies/ml. Slower decay rates occur in individuals who experience intermittent episodes of plasma viremia. Our findings indicate that the persistence of the latent reservoir of HIV-1 despite prolonged treatment is due not only to its slow intrinsic decay characteristics but also to the inability of current drug regimens to completely block HIV-1 replication.

Summary Background In chronic HIV-1 infection, dynamic equilibrium exists between viral production and clearance. The half-life of free virions can be estimated by inhibiting virion production with antiretroviral agents and modelling the resulting decline in plasma HIV-1 RNA. To define HIV-1 and hepatitis C virus (HCV) dynamics, we used plasma apheresis to increase virion clearance temporarily while leaving virion production unaffected. Methods Plasma virus loads were measured frequently before, during, and after apheresis in four HIV-1-infected patients, two of whom were also co-infected with HCV. Rates of virion clearance were derived by non-linear least-square fitting of plasma virus load to a model of viral dynamics. Findings Virion clearance rate constants were 0·0063/min (9·1/day) to 0·025/min (36·0/day; half-life 28–110 min) for HIV-1 and 0·0038/min (5·5/day) to 0·0069/min (9·9/day; half-life 100–182 min) for HCV. These values provided estimates of daily particle production of 9·3 log 10 -10·2 log 10 particles for HIV-1 and 11·6 log 10 -13·0 log 10 particles for HCV. Interpretation Our findings confirm that HIV-1 and HCV are produced and cleared extremely rapidly. New estimates for HIV-1 clearance are up to ten times higher than previous ones, whereas HCV clearance is similar to previous estimates.

The emergence of drug-resistant human immunodeficiency virus type 1 is a frequent cause of failure of combination therapies comprising reverse transcriptase and protease inhibitors. Rational design of salvage therapies requires new methods to assess drug susceptibility. A novel phenotypic drug susceptibility assay was developed and used to measure the drug susceptibilities of viruses obtained from 2 patients treated with zidovudine, lamivudine, and nelfinavir. Results showed that phenotypic drug resistance may be detectable before virus load rebound, treatment failure does not always imply viral resistance to all drugs in a treatment regimen, and persons with similar antiviral treatment histories and clinical courses may have different phenotypic drug resistance profiles at the time that treatment fails.