Although HAART suppresses HIV replication, it is often unable to restore immune homeostasis. Consequently, non-AIDS-defining diseases are increasingly seen in treated individuals. This is attributed to persistent virus expression in reservoirs and to cell activation. Of note, in CD4+ T cells and monocyte-macrophages of virologically-suppressed individuals, there is continued expression of multi-spliced transcripts encoding HIV regulatory proteins. Among them, Tat is essential for virus gene expression and replication, either in primary infection or for virus reactivation during HAART, when Tat is expressed, released extracellularly and exerts, on both the virus and the immune system, effects that contribute to disease maintenance. Here we report results of an ad hoc exploratory interim analysis (up to 48 weeks) on 87 virologically-suppressed HAART-treated individuals enrolled in a phase II randomized open-label multicentric clinical trial of therapeutic immunization with Tat (ISS T-002). Eighty-eight virologically-suppressed HAART-treated individuals, enrolled in a parallel prospective observational study at the same sites (ISS OBS T-002), served for intergroup comparison. Immunization with Tat was safe, induced durable immune responses, and modified the pattern of CD4+ and CD8+ cellular activation (CD38 and HLA-DR) together with reduction of biochemical activation markers and persistent increases of regulatory T cells. This was accompanied by a progressive increment of CD4+ T cells and B cells with reduction of CD8+ T cells and NK cells, which were independent from the type of antiretroviral regimen. Increase in central and effector memory and reduction in terminally-differentiated effector memory CD4+ and CD8+ T cells were accompanied by increases of CD4+ and CD8+ T cell responses against Env and recall antigens. Of note, more immune-compromised individuals experienced greater therapeutic effects. In contrast, these changes were opposite, absent or partial in the OBS population. These findings support the use of Tat immunization to intensify HAART efficacy and to restore immune homeostasis.Trial registrationClinicalTrials.gov NCT00751595
BackgroundThe phase II multicenter, randomized, open label, therapeutic trial (ISS T-002, Clinicaltrials.gov NCT00751595) was aimed at evaluating the immunogenicity and the safety of the biologically active HIV-1 Tat protein administered at 7.5 or 30 μg, given 3 or 5 times monthly, and at exploring immunological and virological disease biomarkers. The study duration was 48 weeks, however, vaccinees were followed until the last enrolled subject reached the 48 weeks.Reported are final data up to 144 weeks of follow-up. The ISS T-002 trial was conducted in 11 clinical centers in Italy on 168 HIV positive subjects under Highly Active Antiretroviral Therapy (HAART), anti-Tat Antibody (Ab) negative at baseline, with plasma viremia <50 copies/mL in the last 6 months prior to enrollment, and CD4+ T-cell number ≥200 cells/μL. Subjects from a parallel observational study (ISS OBS T-002, Clinicaltrials.gov NCT0102455) enrolled at the same clinical sites with the same criteria constituted an external reference group to explore biomarkers of disease.ResultsThe vaccine was safe and well tolerated and induced anti-Tat Abs in most patients (79%), with the highest frequency and durability in the Tat 30 μg groups (89%) particularly when given 3 times (92%). Vaccination promoted a durable and significant restoration of T, B, natural killer (NK) cells, and CD4+ and CD8+ central memory subsets. Moreover, a significant reduction of blood proviral DNA was seen after week 72, particularly under PI-based regimens and with Tat 30 μg given 3 times (30 μg, 3x), reaching a predicted 70% decay after 3 years from vaccination with a half-life of 88 weeks. This decay was significantly associated with anti-Tat IgM and IgG Abs and neutralization of Tat-mediated entry of oligomeric Env in dendritic cells, which predicted HIV-1 DNA decay. Finally, the 30 μg, 3x group was the only one showing significant increases of NK cells and CD38+HLA-DR+/CD8+ T cells, a phenotype associated with increased killing activity in elite controllers.ConclusionsAnti-Tat immune responses are needed to restore immune homeostasis and effective anti-viral responses capable of attacking the virus reservoir. Thus, Tat immunization represents a promising pathogenesis-driven intervention to intensify HAART efficacy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12977-015-0151-y) contains supplementary material, which is available to authorized users.
Resistance to antivirals is a complex and dynamic phenomenon that involves more mutations than are currently known. Here, we characterize 10 additional mutations (L74V, K101Q, I135M/T, V179I, H221Y, K223E/Q, and L228H/R) in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase which are involved in the regulation of resistance to nonnucleoside reverse transcriptase inhibitors (NNRTIs). These mutations are strongly associated with NNRTI failure and strongly correlate with the classical NNRTI resistance mutations in a data set of 1,904 HIV-1 B-subtype pol sequences from 758 drug-naïve patients, 592 nucleoside reverse transcriptase inhibitor (NRTI)-treated but NNRTI-naïve patients, and 554 patients treated with both NRTIs and NNRTIs. In particular, L74V and H221Y, positively correlated with Y181C, were associated with an increase in Y181C-mediated resistance to nevirapine, while I135M/T mutations, positively correlated with K103N, were associated with an increase in K103N-mediated resistance to efavirenz. In addition, the presence of the I135T polymorphism in NNRTI-naïve patients significantly correlated with the appearance of K103N in cases of NNRTI failure, suggesting that I135T may represent a crucial determinant of NNRTI resistance evolution. Molecular dynamics simulations show that I135T can contribute to the stabilization of the K103N-induced closure of the NNRTI binding pocket by reducing the distance and increasing the number of hydrogen bonds between 103N and 188Y. H221Y also showed negative correlations with type 2 thymidine analogue mutations (TAM2s); its copresence with the TAM2s was associated with a higher level of zidovudine susceptibility. Our study reinforces the complexity of NNRTI resistance and the significant interplay between NRTI-and NNRTI-selected mutations. Mutations beyond those currently known to confer resistance should be considered for a better prediction of clinical response to reverse transcriptase inhibitors and for the development of more efficient new-generation NNRTIs.
Background: We tested whether pre-HAART viraemia affects the achievement and maintenance of virological success in HIV-1-infected patients starting modern firstline therapies. Methods: A total of 1,430 patients starting their first HAART (genotype-tailored) in 2008 (median; IQR: 2006-2009) were grouped according to levels of pre-HAART viraemia (≤30,000, 30,001-100,000, 100,001-300,000, 300,001-500,000 and >500,000 copies/ml). The impact of pre-therapy viraemia on the time to virological success (viraemia ≤50 copies/ml) and on the time to virological rebound (first of two consecutive viraemia values >50 copies/ml after virological success) were evaluated by Kaplan-Meier curves and Cox regression analyses. Results: Median pre-HAART viraemia was 5.1 log 10 copies/ml (IQR 4.5-5.5), and 53% of patients had viraemia >100,000 copies/ml. By week 48, the prevalence of patients reaching virological success was >90% in all pre-HAART viraemia ranges, with the only exception of range >500,000 copies/ml (virological success =83%; P<0.001). Higher pre-HAART viraemia was tightly correlated with longer median time to achieve virological success. Cox multivariable estimates confirmed this result: patients with pre-HAART viraemia >500,000 copies/ml showed the lowest hazard of virological undetectability after adjusting for age, gender, pre-HAART CD4 + T-cell count, transmitted drug resistance, calendar year and third drug administered (adjusted hazard ratio [95% CI]: 0.27 [0.21, 0.35]; P<0.001). Pre-HAART viraemia >500,000 copies/ml was also associated with higher probability of virological rebound compared with patients belonging to lower viraemia strata at weeks 4, 12 and 24 (P=0.050). Conclusions: At the time of modern HAART, and even though an average >90% of virological success, high pre-HAART viraemia remains an independent factor associated with delayed and decreased virological success. Patients starting HAART with >500,000 copies/ml represent a significant population that may deserve special attention.HAART has significantly extended the time to development of AIDS and to death in HIV-infected individuals [1,2]. Its efficacy in suppression of plasma HIV-1 RNA to undetectable levels, and in increasing CD4 + T-cell count, is well documented in several clinical trials [3][4][5][6].Despite years of great progress in treating AIDS, however, in some patients starting their first treatment; the effectiveness of HAART is still not sufficient, with consequent virological failures [7][8][9]. These failures can be caused by several factors, such as drug potency, drug
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