CD8+ T-cell activation in HIV-1-infected patients experiencing transient low-level viremia during antiretroviral therapy

Persistent Low-Level Viremia is an Independent Risk Factor for Virologic Failure: A Retrospective Cohort Study in China

Background

Whether intermittent low-level viremia (iLLV/blip) or persistent low-level viremia (pLLV) increases the risk of virologic failure (VF) in HIV-1 patients is controversial. The objective of this study was to investigate the incidence of blip/pLLV and the association between blip/pLLV and VF in a Chinese antiretroviral therapy cohort.

Methods

HIV-1 patients who underwent antiretroviral therapy (ART) from 2005 to 2018 and had at least two viral load (VL) measurements after a minimum of 6 months ART treatment were included. VF was defined as one or more VL measurements of ≥1000 copies/mL. Blip was described as an isolated VL measurement between 50 and 999 copies/mL, and pLLV was defined as two or more consecutive VL measurements between 50 and 999 copies/mL. Blip and pLLV were categorized separately into three groups: 50–200, 201–400 and 401–999 copies/mL. The Cox proportional hazard model was used to explore the association between blip/pLLV and VF.

Results

In total, 8098 participants were enrolled in this long-term cohort study. A 94.3% of the participants were male and among which 77.3% were infected through homosexual transmission. Blip occurred in 4.0% (325/8098) of the patients with an incidence of 0.73 per 100 person-years (/100 PYS) of follow-up (95% CI: 0.71–0.76), whereas pLLV occurred in 1.3% of the patients (102/8098) with an incidence of 0.23/100 PYS of follow-up (95% CI: 0.21–0.25). All the three categories of pLLV were associated with VF: pLLV 50–200 [aHR: 3.82 (1.95–7.47)], pLLV 201–400 [aHR: 5.36 (2.35–12.22)] and pLLV 401–999 [aHR: 13.51 (8.28–22.02)]. However, blip is not significantly associated with VF in any category.

Conclusion

Our study suggested that patients with pLLV had an increased risk of subsequent VF. Therefore, if pLLV occurs in patients, monitoring and corresponding measurements must be strengthened to avoid the subsequent VF.

HIV-1 viral blips are associated with repeated and increasingly high levels of cell-associated HIV-1 RNA transcriptional activity

OBJECTIVE

Some HIV+ patients, virally suppressed on ART, show occasional 'blips' of detectable HIV-1 plasma RNA. We used a new highly sensitive assay of cell-associated HIV-1 RNA to measure transcriptional activity in PBMCs and production of infectious virus from the viral reservoir, in patients with and without 'blips'.

DESIGN/METHODS

RNA and DNA extracted from cells in 6 ml of peripheral blood, from suppressed patients with one to two 'blip' episodes over the past 2 years of ART (n = 55), or no 'blips' (n = 52), were assayed for HIV-1 RNA transcripts and proviral DNA targeting the highly conserved 'R' region of the LTR. Follow-up samples were also collected. Purified CD4+ T cells were cultured with anti-CD3/CD28/CD2 T-cell activator to amplify transcription and measure replication competent virus.

RESULTS

HIV-1 RNA transcripts ranged from 1.3 to 5415 copies/106 white blood cells. 'Blip' patients had significantly higher levels vs. without blips (median 192 vs. 49; P = 0.0007), which correlated with: higher levels of inducible transcripts after activation in vitro, sustained higher HIV-1 transcription levels in follow-up samples along with increasing HIV-1 DNA in some, and production of replication-competent HIV-1.

CONCLUSION

Viral 'blips' are significant reflecting higher transcriptional activity from the reservoir and contribute to the reservoir over time. This sensitive assay can be used in monitoring the size and activity of the HIV-1 reservoir and will be useful in HIV-1 cure strategies.

The role of CD38 in HIV infection

The widely-expressed molecule CD38 is a single-stranded type II transmembrane glycoprotein that is mainly involved in regulating the differentiation and activation state of the cell. CD38 has broad and complex functions, including enzymatic activity, intercellular signal transduction, cell activation, cytokine production, receptor function and adhesion activity, and it plays an important role in the physiological and pathological processes of many diseases. Many studies have shown that CD38 is related to the occurrence and development of HIV infection, and CD38 may regulate its progression through different mechanisms. Therefore, investigating the role of CD38 in HIV infection and the potential signaling pathways that are involved may provide a new perspective on potential treatments for HIV infection. In the present review, the current understanding of the roles CD38 plays in HIV infection are summarized. In addition, the specific role of CD38 in the process of HIV infection of human CD4⁺ T lymphocytes is also discussed.

Persistent high levels of immune activation and their correlation with the HIV-1 proviral DNA and 2-LTR circles loads, in a cohort of Mexican individuals following long-term and fully suppressive treatment

OBJECTIVES

The aim of this study was to investigate the correlation between the HIV-1 reservoir and the levels of immune activation in chronic patients under fully suppressive cART.

METHODS

We quantified the HIV proviral DNA and 2-LTR circles loads from PBMCs, the levels of CD38+ and Ki-67+ T-cells, and the levels of IL-7 in a cohort of patients with more than 5 years of ART at enrollment and after 1 year.

RESULTS

In 29 participants with a median of 8 years (IQR, 6.9-9.4) under suppressive cART we found higher levels of CD8+ CD38+ T-cells after 1-year (P = .000). There was a non-statistically significant poor correlation between the levels of immune activation and the proviral DNA of CD4+ and CD8+ T-cells. Ki-67+ T-cells declined without significant differences, and there was no significant correlation with the proportion of CD38+. IL-7 decreased at the follow-up observation (P = .094), but there was no correlation with the levels of CD38+ and Ki-67+ T-cells.

CONCLUSIONS

We found a weak but non-statistically significant correlation of the levels of T-cell activation with the proviral DNA and 2-LTR circles. This suggests the likely occurrence of further mechanisms driving chronic versus early immune activation other than viral replication by itself in chronic patients.

Patterns of detectable viraemia among children and adults with HIV infection taking antiretroviral therapy in Zimbabwe

OBJECTIVE

To investigate the incidence and predictors of viraemia among individuals on antiretroviral therapy (ART) in Harare, Zimbabwe.

METHODS

Children (0-19 years) and adults (>19 years) starting ART between 2013 and 2015 were followed for a median of 2.8 and 2.7 years, respectively. The incidence rates of virological failure (VF), low-level viraemia (LLV), and viral blips were assessed and the predictors of viraemia were determined using logistic and parametric survival regression analyses.

RESULTS

A total of 630 individuals initiated ART, and 19.7% of children and 5.6% of adults did not achieve viral suppression by 12 months. Younger age and CD4 count ≤200 cells/mm3 at baseline were associated with not being virally suppressed at 12 months in adults. Among those who achieved viral suppression during the follow-up period, the incidence of VF was higher in children (4.0/100 person-years vs. 0.4/100 person-years in adults; p<0.001), as was the incidence of LLV (1.9/100 person-years vs. 0.3/100 person-years in adults; p=0.03). The incidence rate of blips was 10.9 per 100 person-years in children and 4.0 per 100 person-years in adults.

CONCLUSIONS

Children are less likely to reach viral suppression and are at higher risk of viraemia while on ART than adults. The significance of LLV and blips needs further study.

Is weak CD4+ gain in the course of suppressive combination antiretroviral therapy for HIV infection a current clinical challenge? A case report and brief review of the literature

Background

Individuals lacking immune recovery during suppressive cART will still represent a clinical issue in the years to come, given the high proportion of HIV-infected subjects introducing therapy late in the course of disease. Understanding the mechanisms underlying poor CD4+ T-cell gain is crucial for the correct clinical management of individuals in this context.

Case presentation

An HIV-infected subject with poor CD4+ T-cell gain in the course of suppressive antiretroviral therapy was extensively investigated to identify the mechanisms behind inadequate CD4+ reconstitution. In particular, we studied the phenotype of circulating T-cells, interleukin-7 signaling in peripheral blood and bone marrow, gut function and microbial translocation markers as well as the composition of the faecal microbiota. Numerous therapeutic interventions ranging from antiretroviral therapy intensification to immunotherapy and anti-hepatitis C virus treatment were also employed in order to target the possible causes of poor immune-recovery.

Conclusions

Poor CD4+ T-cell gain on suppressive antiretroviral therapy is multifactorial and thus represents a clinical challenge. Clinicians should investigate subjects’ immune profile as well as possible causes of chronic antigenic stimulation for the administration of the most appropriate therapeutic strategies in this setting.

Polymorphisms in the CD14 and TLR4 genes independently predict CD4+ T-cell recovery in HIV-infected individuals on antiretroviral therapy

BACKGROUND

Chronic HIV infection leads to marked depletion of CD4 T cells in the gastrointestinal tract and increased microbial translocation measured by an increase in circulating lipopolysaccharide (LPS) levels. Here, we hypothesized that single-nucleotide polymorphisms (SNPs) in genes encoding the Toll-like receptor 4 (TLR4) and CD14, the principal receptors for LPS, were associated with CD4 T-cell recovery postantiretroviral therapy (ART).

METHODS

Prospective study of predominantly white HIV-infected participants receiving suppressive ART for at least 12 months. We analysed the CD14 SNPs C-260T and the TLR4 SNPs A+896G, C+1196T. We also determined the levels of LPS and soluble CD14 in plasma samples collected pre-ART and post-ART initiation. CD4 T-cell recovery was assessed by linear mixed models.

RESULTS

Following ART, individuals with a TT genotype compared with a CT or CC genotype for CD14 C-260T SNP showed higher levels of soluble CD14 (P = 0.008 and 0.003, respectively). The CC genotype for the CD14 C-260T SNP, compared with CT or TT, and the TLR4 SNP (AC/GT), compared with the homozygous genotype (AA/CC), were both independently associated with enhanced long-term CD4 T-cell recovery (>3 months; P < 0.001).

CONCLUSION

Polymorphisms in CD14 and TLR4 are independently associated with long-term CD4 T-cell recovery in HIV-infected individuals post-ART.

Increased CD38 expression on T lymphocytes as a marker of HIV dissemination into the central nervous system

Cross-sectional analysis on 20 HIV-1 patients with neurological symptoms admitted to two infectious disease units. Cut-off of HIV-RNA (VL) was 20 copies/ml for plasma and cerebral spinal fluid (CSF). Flow cytometry was used to analyze the phenotype of circulating and CSF T lymphocytes. CD38 mean fluorescence intensity (MFI) was higher on circulating CD4+T lymphocytes from patients with VL>20 copies/ml in plasma (P=0.001) or CSF (P=0.001). The frequency of circulating CD8+CD38+T cells and CD38 MFI on these cells were higher in patients with VL>20 copies/ml than in those with undetectable plasma VL (P=0.030 and P=0.023). The frequency of CSF CD4+CD38+T, as well as their CD38 and CD95 MFI, were increased in patients with detectable than non-detectable plasma VL (P=0.01, P=0.03, and P=0.05). The % CD38+CD8+T in CSF correlated with time of virological suppression (ρ=-0.462, P=0.040) and the CNS penetration-effectiveness (CPE) score (ρ=-0.467, P=0.038). In conclusion, (a) the expression of CD38+ on both CD4+, CD8+T lymphocytes from peripheral blood and CSF discriminated between viremic and non-viremic patients and (b) T cell activation/apoptosis markers inversely correlated with CPE to remark the importance for therapy to restore immunological functions.

Soluble biomarkers of immune activation and inflammation in HIV infection: impact of 2 years of effective first-line combination antiretroviral therapy

OBJECTIVES

The aim of the study was to assess the impact of rapid and sustained viral control produced by combination antiretroviral therapy (cART) on HIV-associated immune activation and inflammation.

METHODS

In this longitudinal observational study, we examined changes in interleukin-6 (IL-6), interferon-γ-inducible protein-10 (IP-10), monokine induced by interferon-γ (MIG) and soluble CD14 (sCD14) levels during 2 years of effective first-line cART. Biomarker levels before and after cART were compared with those observed in healthy subjects, using the Wilcoxon signed rank test. Elevated biomarker levels were defined with respect to values for healthy subject (mean + 2 standard deviations). Factors associated with persistently elevated biomarker levels after 2 years of cART were identified by logistic regression.

RESULTS

We included in the study 139 patients with a median HIV-1 RNA level of 4.8 log10 HIV-1 RNA copies/mL and a median CD4 cell count of 294 cells/μL at cART initiation [day 0 (D0)]. At D0, all biomarker levels were higher than in healthy subjects (P < 0.05). After 2 years of cART, IL-6, IP-10 and MIG levels fell significantly, by a median of 0.54, 420 and 1107 pg/mL, respectively (all P < 0.001), and were no longer elevated in > 75% of patients. In contrast, sCD14 levels did not change significantly (0.18 × 10(6)  pg/mL; P = 0.102) and remained elevated. Older age was associated with elevated levels of IP-10 [odds ratio (OR) 1.60 per 10 years older; P = 0.047] and MIG (OR 1.92 per 10 years older; P = 0.007) after 2 years of cART.

CONCLUSIONS

The rapid and sustained viral suppression produced by first-line cART reduced IL-6, IP-10 and MIG to normal levels, while sCD14, a marker of monocyte activation, remained elevated. High levels of IP-10 and MIG tended to persist in older patients.

Latent and Active Tuberculosis Infection Increase Immune Activation in Individuals Co-Infected with HIV

In recent years, chronic immune activation and systemic inflammation have emerged as hallmarks of HIV disease progression and mortality. Several studies indicate that soluble inflammatory biomarkers (sCD14, IL-6, IL-8, CRP and hyaluronic acid), as well as surface markers of T-cell activation (CD38, HLA-DR) independently predict progression to AIDS and mortality in HIV-infected individuals. While co-infections have been shown to contribute to immune activation, the impact of latent tuberculosis infection (LTBI), which is widely endemic in the areas most affected by the global AIDS epidemic, has not been evaluated. We hypothesized that both active and latent states of Mycobacterium tuberculosis co-infection contribute to elevated immune activation as measured by these markers. In HIV-infected individuals with active, but not latent TB, we found elevated levels of soluble markers associated with monocyte activation. Interestingly, T-cell activation was elevated individuals with both latent and active TB. These results suggest that in the highly TB- and HIV-endemic settings of southern Africa, latent TB-associated T-cell activation may contribute to HIV disease progression and exacerbate the HIV epidemic. In addition, our findings indicate that aggressive campaigns to treat LTBI in HIV-infected individuals in high-burden countries will not only impact TB rates, but may also slow HIV progression.

Significance

Latent tuberculosis, which affects an estimated 1/3 of the world's population, has long been thought to be a relatively benign, quiescent state of M. tuberculosis infection. While HIV co-infection is known to exacerbate M. tuberculosis infection and increase the risk of developing active TB, little is known about the potential effect of latent TB infection on HIV disease. This study shows that HIV-infected individuals with both active and latent TB have elevated levels of inflammation and immune activation, biomarkers of HIV disease progression and elevated risk of mortality. These results suggest that, in the context of HIV, latent TB infection may be associated with increased risk of progression to AIDS and mortality.

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While HIV co-infection is known to exacerbate TB, little is known about the effect of latent TB infection on HIV disease.

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In HIV-infected individuals, active and latent TB elevate immunological biomarkers of HIV morbidity and mortality.

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In the context of HIV, latent TB infection may be associated with increased risk of progression to AIDS and mortality.

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In addition to reducing TB transmission, aggressive treatment of latent TB infection may also reduce the progression of HIV.

Tripterygium wilfordii Hook F extract in cART-treated HIV patients with poor immune response: a pilot study to assess its immunomodulatory effects and safety

BACKGROUND

Despite combination antiretroviral therapy (cART), 20% of HIV-infected patients are unable to achieve adequate immunologic recovery, in which immune activation plays a crucial role. We hypothesize that extract of Tripterygium wilfordii Hook F (TwHF), a Chinese medication used to treat autoimmune diseases, has immunomodulatory effects that may help CD4 cell recovery.

METHODS

Eighteen cART-treated HIV-infected patients virally suppressed for over 12 months with suboptimal CD4 cell recovery were enrolled. TwHF extract was administered at a dosage of 10 mg three times daily for 12 months. T-cell subsets and activation markers were evaluated at baseline and during follow-up. The trial was registered at Clinicaltrials.gov (NCT02002286).

RESULTS

TwHF extract was associated with a mean increase in CD4 cell count of 88 cells/μl (95% confidential interval [CI], 72-105 cells/μl) after one year of treatment. A significant increase in the mean rate of CD4 cell recovery (26 before vs 75 cells/μl/year after TwHF use, P < 0.001) was observed. Analysis of 13 patients with activation profiles suggested that TwHF extract was associated with a decrease in T-cell immune activation which was temporally correlated with CD4 cell recovery. No discontinuation of TwHF extract was reported.

CONCLUSION

Use of TwHF extract in HIV-infected patients was associated with a reduction in T-cell activation and improved CD4 recovery with an excellent safety profile.

Factors associated with CD8+ T-cell activation in HIV-1-infected patients on long-term antiretroviral therapy

BACKGROUND

Abnormal levels of CD8 T-cell activation persist in HIV-1-infected patients on suppressive antiretroviral therapy (ART) and may be deleterious.

METHODS

CD8 T-cell activation (% coexpressing CD38/HLA-DR) was analyzed on blood specimens from 833 HIV-1-infected patients on ART for ≥96 weeks with concurrent plasma HIV RNA (vRNA) ≤200 copies per milliliter. Factors associated with CD8 T-cell activation were assessed using generalized estimating equations to incorporate longitudinal measurements (median 4/participant).

RESULTS

Participants were 84% men, 47% white, 28% black, and 22% Hispanic, with median pre-ART age 38 years and median ART exposure 144 weeks. CD8 T-cell activation was higher at timepoints when vRNA was 51-200 versus ≤50 copies per milliliter [mean CD8 T-cell activation 23.4% vs. 19.7%; adjusted difference: 1.7% (95% confidence interval: 0.1 to 3.4), P = 0.042]. Restricting to vRNA ≤50 copies per milliliter, multivariable models showed the following factors associated with higher CD8 T-cell activation: older age [≥45 vs. ≤30 years: 3.6% (1.4 to 5.7), P = 0.004], hepatitis C virus antibody positivity [3.6% (0.9 to 6.2), P = 0.032], Hispanic vs. white [7.2% (5.3 to 9.0), P < 0.001], lower concurrent CD4 count [≤200 vs. >500 cells/mm: 2.2% (0.7 to 3.7), P < 0.001], lower concurrent CD4/CD8 ratio [-2.6% (-3.7 to -1.5) per 0.5 unit increase, P < 0.001], and higher pre-ART CD8 T-cell activation [2.0% (1.6 to 2.5) per 10% higher, P < 0.001].

CONCLUSIONS

In participants included in our analysis, residual low-level viremia between 51 and 200 copies per milliliter during ART was shown to be associated with greater CD8 T-cell activation than full suppression to <50 copies per milliliter. Older age, hepatitis C virus antibody positivity, race/ethnicity, higher pre-ART CD8 T-cell activation, and lower concurrent CD4/CD8 ratio and CD4 T-cell count also contribute to greater CD8 T-cell activation during suppressive ART.

Potential implication of residual viremia in patients on effective antiretroviral therapy

The current antiretroviral therapy (ART) has suppressed viremia to below the limit of detection of clinical viral load assays; however, it cannot eliminate viremia completely in the body even after prolonged treatment. Plasma HIV-1 loads persist at extremely low levels below the clinical detection limit. This low-level viremia (termed "residual viremia") cannot be abolished in most patients, even after the addition of a new class of drug, i.e., viral integrase inhibitor, to the combined antiretroviral regimens. Neither the cellular source nor the clinical significance of this residual viremia in patients on ART remains fully clear at present. Since residual plasma viruses generally do not evolve with time in the presence of effective ART, one prediction is that these viruses are persistently released at low levels from one or more stable but yet unknown HIV-1 reservoirs in the body during therapy. This review attempts to emphasize the source of residual viremia as another important reservoir (namely, "active reservoir") distinct from the well-known latent HIV-1 reservoir in the body, and why its elimination should be a priority in the effort for HIV-1 eradication.

Residual viremia is preceding viral blips and persistent low-level viremia in treated HIV-1 patients

BACKGROUND

It has been suggested that low-level viremia or blips in HIV-infected patients on antiretroviral treatment are related to assay variation and/or increased sensitivity of new commercial assays. The 50-copy cut-off for virologic failure is, therefore, under debate.

METHODS

Treated patients with low-level viremia (persistent viral loads (VL) of 50-1000 copies/mL, group A, N = 16) or a blip (single detectable VL, group B, N = 77) were compared to a control group (consistently suppressed viremia since start therapy (<50 copies/mL), N = 79). Residual viremia (detectable viral RNA <50 copies/ml) in the year preceding the first VL above 50 copies/mL (T0) was determined using Roche Cobas-Amplicor v1.5 or CAP-CTM v2.0. Subsequent virologic failure (2 consecutive VLs>500 or 1 VL>1000 copies/mL that was not followed by a VL<50 copies/mL; median follow up 34 months) was assessed.

RESULTS

Significantly more patients in groups A and B had residual viremia in the year preceding T0 compared to controls (50% and 19% vs 3% respectively; p<0.001). Residual viremia was associated with development of low-level viremia or blips (OR 10.9 (95% CI 2.9-40.6)). Subsequent virologic failure was seen more often in group A (3/16) and B (2/77) than in the control group (0/79).

CONCLUSION

Residual viremia is associated with development of blips and low-level viremia. Virologic failure occurred more often in patients with low-level viremia. These results suggest that low-level viremia results from viral production/replication rather than only assay variation.

Significance and clinical management of persistent low-level viremia and very-low-level viremia in HIV-1-infected patients

A goal of HIV therapy is to sustain suppression of the plasma viral load below the detection limits of clinical assays. However, widely followed treatment guidelines diverge in their interpretation and recommended management of persistent viremia of low magnitude, reflecting the limited evidence base for this common clinical finding. Here, we review the incidence, risk factors, and potential consequences of low-level HIV viremia (LLV; defined in this review as a viremia level of 50 to 500 copies/ml) and very-low-level viremia (VLLV; defined as a viremia level of <50 copies/ml detected by clinical assays that have quantification cutoffs of <50 copies/ml). Using this framework, we discuss practical issues related to the diagnosis and management of patients experiencing persistent LLV and VLLV. Compared to viral suppression at <50 or 40 copies/ml, persistent LLV is associated with increased risk of antiretroviral drug resistance and overt virologic failure. Higher immune activation and HIV transmission may be additional undesirable consequences in this population. It is uncertain whether LLV of <200 copies/ml confers independent risks, as this level of viremia may reflect assay-dependent artifacts or biologically meaningful events during suppression. Resistance genotyping should be considered in patients with persistent LLV when feasible, and treatment should be modified if resistance is detected. There is a dearth of clinical evidence to guide management when genotyping is not feasible. Increased availability of genotypic assays for samples with viral loads of <400 copies/ml is needed.

Immune activation throughout a boosted darunavir monotherapy simplification strategy

Our aim was to assess the evolution and the impact that blips, intermittent low-level viraemia and virological failure (VF) episodes have on patients' immune activation (IA) profiles during ritonavir-boosted darunavir monotherapy (mtDRV/rtv). A prospective cohort of human immunodeficiency virus-1-infected patients who switched to mtDRV/rtv was followed for 2 years. Cellular IA was assessed according to HLA-DR and CD38 expression in CD4(+) and CD8(+) T-cells and their naïve, effector memory and central memory subpopulations, and systemic IA was evaluated according to sCD14 and D-dimer levels. Seventy-five patients from the MonDAR cohort were selected for this substudy, and classified according to viral outcome as having continuous undetectable viraemia (n = 19), blips (n = 19), intermittent viraemia (n = 21), and VF (n = 16). The IA profile was closely linked to viral behaviour. Patients on viral suppression for 24 months showed a significant decrease in CD4(+) and CD8(+) T-cell activation and sCD14 and D-dimer levels. Patients with transient low-level viraemia episodes (blips and intermittent viraemia) showed cellular and systemic IA similar to baseline values. In contrast, significant increases in T-cell activation and sCD14 and D-dimer levels were observed in patients with VF. Baseline levels of HLA-DR(+)CD38(+)CD8(+) T-cells of >6.4% were independently associated with the emergence of VF. Therefore, mtDRV/rtv might be considered as a safe simplification strategy, on the basis of the IA results, whenever viral replication is under medium-term and long-term control. Transient low-level viraemia episodes do not affect patients' IA status. Moreover, HLA-DR(+)CD38(+)CD8(+) T-cell baseline levels should be considered when patients are switched to mtDRV/rtv.

Immune activation and HIV persistence: implications for curative approaches to HIV infection

Despite complete or near-complete suppression of human immunodeficiency virus (HIV) replication with combination antiretroviral therapy, both HIV and chronic inflammation/immune dysfunction persist indefinitely. Untangling the association between the virus and the host immune environment during therapy might lead to novel interventions aimed at either curing the infection or preventing the development of inflammation-associated end-organ disease. Chronic inflammation and immune dysfunction might lead to HIV persistence by causing virus production, generating new target cells, enabling infecting of activated and resting target cells, altering the migration patterns of susceptible target cells, increasing the proliferation of infected cells, and preventing normal HIV-specific clearance mechanisms from function. Chronic HIV production or replication might contribute to persistent inflammation and immune dysfunction. The rapidly evolving data on these issues strongly suggest that a vicious cycle might exist in which HIV persistence causes inflammation that in turn contributes to HIV persistence.

Performance of HIV-1 drug resistance testing at low-level viremia and its ability to predict future virologic outcomes and viral evolution in treatment-naive individuals

BACKGROUND

Low-level viremia (LLV; human immunodeficiency virus [HIV-1] RNA 50-999 copies/mL) occurs frequently in patients receiving antiretroviral therapy (ART), but there are few or no data available demonstrating that HIV-1 drug resistance testing at a plasma viral load (pVL) <1000 copies/mL provides potentially clinically useful information. Here, we assess the ability to perform resistance testing by genotyping at LLV and whether it is predictive of future virologic outcomes in patients beginning ART.

METHODS

Resistance testing by genotyping at LLV was attempted on 4915 plasma samples from 2492 patients. A subset of previously ART-naive patients was analyzed who achieved undetectable pVL and subsequently rebounded with LLV (n = 212). A genotypic sensitivity score (GSS) was calculated based on therapy and resistance testing results by genotyping, and stratified according to number of active drugs.

RESULTS

Eighty-eight percent of LLV resistance assays produced useable sequences, with higher success at higher pVL. Overall, 16 of 212 (8%) patients had pretherapy resistance. Thirty-eight of 196 (19%) patients without pretherapy resistance evolved resistance to 1 or more drug classes, primarily the nucleoside reverse transcriptase (14%) and/or nonnucleoside reverse transcriptase (9%) inhibitors. Patients with resistance at LLV (GSS <3) had a 2.1-fold higher risk of virologic failure (95% confidence interval, 1.2- to 3.7-fold) than those without resistance (P = .007). Progressively lower GSS scores at LLV were associated with a higher increase in pVL over time (P < .001). Acquisition of additional resistance mutations to a new class of antiretroviral drugs during LLV was not found in a subset of patients.

CONCLUSIONS

Routine HIV-1 genotyping of LLV samples can be performed with a reasonably high success rate, and the results appear predictive of future virologic outcomes.

Altering cell death pathways as an approach to cure HIV infection

Recent cases of successful control of human immunodeficiency virus (HIV) by bone marrow transplant in combination with suppressive antiretroviral therapy (ART) and very early initiation of ART have provided proof of concept that HIV infection might now be cured. Current efforts focusing on gene therapy, boosting HIV-specific immunity, reducing inflammation and activation of latency have all been the subject of recent excellent reviews. We now propose an additional avenue of research towards a cure for HIV: targeting HIV apoptosis regulatory pathways. The central enigma of HIV disease is that HIV infection kills most of the CD4 T cells that it infects, but those cells that are spared subsequently become a latent reservoir for HIV against which current medications are ineffective. We propose that if strategies could be devised which would favor the death of all cells which HIV infects, or if all latently infected cells that release HIV would succumb to viral-induced cytotoxicity, then these approaches combined with effective ART to prevent spreading infection, would together result in a cure for HIV. This premise is supported by observations in other viral systems where the relationship between productive infection, apoptosis resistance, and the development of latency or persistence has been established. Therefore we propose that research focused at understanding the mechanisms by which HIV induces apoptosis of infected cells, and ways that some cells escape the pro-apoptotic effects of productive HIV infection are critical to devising novel and rational approaches to cure HIV infection.