Time of initiation of antiretroviral therapy: impact on HIV-1 viraemia. The Swiss HIV Cohort Study

Comparison of two digital PCR methods for EGFR DNA and SARS-CoV-2 RNA quantification

BACKGROUND

The COVID-19 pandemic caused by the severe acute SARS-CoV-2 virus has undeniably highlighted the importance of reliable nucleic acid quantification. Digital PCR (dPCR) is capable of the absolute quantification of nucleic acids.

METHOD

By using the droplet dPCR (QX200) and the digital real-time PCR (LOAA), the copy numbers were compared via multiple assays for three distinct targerts; EGFR DNA, SARS-CoV-2 and HIV-1 RNA.

RESULTS

The droplet dPCR and digital real-time PCR showed similar copy numbers for both DNA and RNA quantification. When the limit of detection (LOD) and limit of quantitation (LOQ) of each method were estimated for DNA and RNA targets, the digital real-time PCR showed a higher sensitivity and precision especially with low copy number targets.

CONCLUSION

The breath of nucleic acid testing in diagnostic applications continues to expand. In this study we applied common diagnostic targets to a novel digital real-time PCR methodology. It performed comparably to the established dPCR method with distinctive advantages and disadvantages for implementing in laboratories. These rapidly developing dPCR systems can be applied to benefit the accurate and sensitive nucleic acid testing for various clinical areas.

Impact of Analytical Treatment Interruption on Burden and Diversification of HIV Peripheral Reservoir: A Pilot Study

BACKGROUND

If analytical antiretroviral-treatment (ART) interruption (ATI) might significantly impact quantitative or qualitative peripheral-total HIV-DNA is still debated.

METHODS

Six chronically HIV-1 infected patients enrolled in APACHE-study were analysed for peripheral-total HIV-DNA and residual viremia, major-resistance-mutations (MRMs) and C2-V3-C3 evolution at pre-ATI (T1), during ATI (T2) and at achievement of virological success after ART-resumption (post-ATI, T3). These data were obtained at three comparable time-points in five chronically HIV-1 infected patients on suppressive ART for ≥1 year, enrolled in MODAt-study.

RESULTS

At T1, APACHE and MODAt individuals had similar peripheral-total HIV-DNA and residual viremia (p = 0.792 and 0.662, respectively), and no significant changes for these parameters were observed between T1 and T3 in both groups. At T1, 4/6 APACHE and 2/5 MODAt carried HIV-DNA MRMs. MRMs disappeared at T3 in 3/4 APACHE. All disappearing MRMs were characterized by T1 intra-patient prevalence <80%, and mainly occurred in APOBEC3-related sites. All MRMs persisted over-time in the 2 MODAt. C2-V3-C3 genetic-distance significantly changed from T1 to T3 in APACHE individuals (+0.36[0.11-0.41], p = 0.04), while no significant changes were found in MODAt. Accordingly, maximum likelihood trees (bootstrap > 70%) and genealogical sorting indices (GSI > 0.50 with p-value < 0.05) showed that T1 C2-V3-C3 DNA sequences were distinct from T2 and T3 viruses in 4/6 APACHE. Virus populations at all three time-points were highly interspersed in MODAt.

CONCLUSIONS

This pilot study indicates that short ATI does not alter peripheral-total HIV-DNA burden and residual viremia, but in some cases could cause a genetic diversification of peripheral viral reservoir in term of both MRMs rearrangement and viral evolution.

Reduction of HIV-1 Reservoir Size and Diversity After 1 Year of cART Among Brazilian Individuals Starting Treatment During Early Stages of Acute Infection

The aim of early combined antiretroviral therapy (cART) of HIV is to limit the seeding of the viral reservoir during the initial phase of infection and, consequently, decrease intrahost viral diversity. Here, we assessed the effect of early cART on size and complexity of the proviral reservoir. Peripheral blood mononuclear cell (PBMC) and plasma samples were obtained from ten HIV-infected Brazilian individuals diagnosed at the acute phase of infection, before (PRE_ART) and 12 months (M12_ART) after suppressive cART. HIV proviral reservoir size was determined by quantitative real-time PCR; intrahost viral diversity of the env C2-V3 region was assessed by single genome amplification or next-generation sequencing in PBMC and plasma, respectively. Mean nucleotide diversity (π) and normalized Shannon entropy (H_SN) were used to infer the complexity of the viral population. Compared to PRE_ART, M12_ART saw an immunological recovery with a gain of ∼200 CD4⁺ T cells (P = 0.008) and a normalization of the CD4/CD8 ratio [1.0 (IQR: 0.88–1.18), P = 0.016], as well as a significant decrease in HIV-1 RNA (∼4 log, P = 0.004) and DNA (∼1 log, P = 0.002) levels. The median time to achieve viral suppression was 3 months (IQR: 2.8–5.8 months). The high intermixing between sequences from both visits suggests that the HIV-1 DNA reservoir remained remarkably stable under cART. After 1 year of cART, there was a minor reduction in proviral π (Pre_ART = 0.20 vs. M12_ART = 0.10; P = 0.156) but a significant decrease in H_SN (Pre_ART = 0.41 vs. M12_ART = 0.25; P = 0.019). We found no correlation between π or H_SN at Pre_ART and the rate of HIV DNA decay, T CD4⁺ counts, or CD4/CD8 ratio at M12_ART. Based on a small cohort of Brazilian infected individuals under early cART and analyses of the env region, 1 year of follow-up suggested a reservoir size reduction, allowed a significant decrease of HIV-1 complexity, and achieved immunological restoration regardless of the initial HIV-1 plasma viral load, CD4⁺ T cell counts, or HIV-1 subtype. However, further studies in the Brazilian setting aiming a longer follow-up and larger cohort are required in this field.

The anti-caspase inhibitor Q-VD-OPH prevents AIDS disease progression in SIV-infected rhesus macaques

Apoptosis has been proposed as a key mechanism responsible for CD4+ T cell depletion and immune dysfunction during HIV infection. We demonstrated that Q-VD-OPH, a caspase inhibitor, inhibits spontaneous and activation-induced death of T cells from SIV-infected rhesus macaques (RMs). When administered during the acute phase of infection, Q-VD-OPH was associated with (a) reduced levels of T cell death, (b) preservation of CD4+/CD8+ T cell ratio in lymphoid organs and in the gut, (c) maintenance of memory CD4+ T cells, and (d) increased specific CD4+ T cell response associated with the expression of cytotoxic molecules. Although therapy was limited to the acute phase of infection, Q-VD-OPH-treated RMs showed lower levels of both viral load and cell-associated SIV DNA as compared with control SIV-infected RMs throughout the chronic phase of infection, and prevented the development of AIDS. Overall, our data demonstrate that Q-VD-OPH injection in SIV-infected RMs may represent an adjunctive therapeutic agent to control HIV infection and delaying disease progression to AIDS.

Impact of Early Initiation of Antiretroviral Therapy in Patients with Acute HIV Infection in Vienna, Austria

Background

It is unclear whether antiretroviral therapy (ART) should be initiated during acute HIV infection. Most recent data provides evidence of benefits of early ART.

Methods

We retrospectively compared the clinical and immunological course of individuals with acute HIV infection, who received ART within 3 months (group A) or not (group B) after diagnosis.

Results

Among the 84 individuals with acute HIV infection, 57 (68%) received ART within 3 months (A) whereas 27 (32%) did not receive ART within 3 months (B), respectively. Clinical progression to CDC stadium B or C within 5 years after the diagnosis of HIV was less common in (A) when compared to (B) (P = 0.002). After twelve months, both the mean increase in CD4+ T cell count and the mean decrease in viral load was more pronounced in (A), when compared to (B) (225 vs. 87 cells/μl; P = 0.002 and -4.19 vs. -1.14 log10 copies/mL; P<0.001). Twenty-four months after diagnosis the mean increase from baseline of CD4+ T cells was still higher in group A compared to group B (251 vs. 67 cells/μl, P = 0.004).

Conclusions

Initiation of ART during acute HIV infection is associated with a lower probability of clinical progression to more advanced CDC stages and significant immunological benefits.

Implications of prioritizing HIV cure: new momentum to overcome old challenges in HIV

Background

Curing HIV is a new strategic priority for several major AIDS organizations. In step with this new priority, HIV cure research and related programs are advancing in low, middle, and high-income country settings. This HIV cure momentum may influence existing HIV programs and research priorities.

Discussion

Despite the early stage of ongoing HIV cure efforts, these changes have directly influenced HIV research funding priorities, pilot programs, and HIV messaging. The building momentum to cure HIV infection may synergize with strategic priorities to better identify adults and infants with very early HIV infection. Although HIV cure represents a new goal, many existing programs and research techniques can be repurposed towards an HIV cure. HIV messages focused on engaging communities towards an HIV cure need to be careful to promote ARV adherence and retention within the HIV continuum of care.

Summary

An increased emphasis within the AIDS field on finding an HIV cure has several important implications. Strengthening connections between HIV cure research and other areas of HIV research may help to catalyze research and facilitate implementation in the future.

Combined ART started during acute HIV infection protects central memory CD4+ T cells and can induce remission

BACKGROUND

Therapeutic control of HIV replication reduces the size of the viral reservoir, particularly among central memory CD4+ T cells, and this effect might be accentuated by early treatment.

METHODS

We examined the effect of ART initiated at the time of the primary HIV infection (early ART), lasting 2 and 6 years in 11 and 10 patients, respectively, on the HIV reservoir in peripheral resting CD4+ T cells, sorted into naive (TN), central memory (TCM), transitional memory (TTM) and effector memory (TEM) cells, by comparison with 11 post-treatment controllers (PTCs).

RESULTS

Between baseline and 2 years, CD4+ T cell subset numbers increased markedly (P < 0.004) and HIV DNA levels decreased in all subsets (P < 0.009). TTM cells represented the majority of reservoir cells at both timepoints, T cell activation status normalized and viral diversity remained stable over time. The HIV reservoir was smaller after 6 years of early ART than after 2 years (P < 0.019), and did not differ between PTCs and patients treated for 6 years. One patient, who had low reservoir levels in all T cell subsets after 2 years of treatment similar to the levels in PTCs, spontaneously controlled viral replication during 18 months off treatment.

CONCLUSIONS

Early prolonged ART thus limits the size of the HIV reservoir, protects long-lived cells from persistent infection and may enhance post-treatment control.

Use of observational data in evaluating treatments: antiretroviral therapy and HIV

Observational data are increasingly used in various therapeutic areas to evaluate the use, effectiveness and side effects of new treatments. Whilst randomized clinical trials remain the gold standard for evaluating the efficacy of new agents, they have a number of limitations for HIV, including the limited number of combinations that are compared and the costs of long-term follow-up. Observational data from seroconverter and clinical cohorts have been used to compare the short- and longer-term effectiveness of different therapy combinations and to evaluate the longer-term risks associated with antiretroviral therapy. Furthermore, they provide the opportunity to evaluate the relative success of more complex patterns of therapy, such as sequencing of different regimens over time. However, because of the nature of these data, a number of potential biases may arise which can influence interpretation.

Cell-associated HIV RNA: a dynamic biomarker of viral persistence

In most HIV-infected individuals adherent to modern antiretroviral therapy (ART), plasma viremia stays undetectable by clinical assays and therefore, additional virological markers for monitoring and predicting therapy responses and for measuring the degree of HIV persistence in patients on ART should be identified. For the above purposes, quantitation of cell-associated HIV biomarkers could provide a useful alternative to measurements of viral RNA in plasma. This review concentrates on cell-associated (CA) HIV RNA with the emphasis on its use as a virological biomarker. We discuss the significance of CA HIV RNA as a prognostic marker of disease progression in untreated patients and as an indicator of residual virus replication and the size of the dynamic viral reservoir in ART-treated patients. Potential value of this biomarker for monitoring the response to ART and to novel HIV eradication therapies is highlighted.

Post-treatment HIV-1 controllers with a long-term virological remission after the interruption of early initiated antiretroviral therapy ANRS VISCONTI Study

Combination antiretroviral therapy (cART) reduces HIV-associated morbidities and mortalities but cannot cure the infection. Given the difficulty of eradicating HIV-1, a functional cure for HIV-infected patients appears to be a more reachable short-term goal. We identified 14 HIV patients (post-treatment controllers [PTCs]) whose viremia remained controlled for several years after the interruption of prolonged cART initiated during the primary infection. Most PTCs lacked the protective HLA B alleles that are overrepresented in spontaneous HIV controllers (HICs); instead, they carried risk-associated HLA alleles that were largely absent among the HICs. Accordingly, the PTCs had poorer CD8+ T cell responses and more severe primary infections than the HICs did. Moreover, the incidence of viral control after the interruption of early antiretroviral therapy was higher among the PTCs than has been reported for spontaneous control. Off therapy, the PTCs were able to maintain and, in some cases, further reduce an extremely low viral reservoir. We found that long-lived HIV-infected CD4+ T cells contributed poorly to the total resting HIV reservoir in the PTCs because of a low rate of infection of naïve T cells and a skewed distribution of resting memory CD4+ T cell subsets. Our results show that early and prolonged cART may allow some individuals with a rather unfavorable background to achieve long-term infection control and may have important implications in the search for a functional HIV cure.

New tools for quantifying HIV-1 reservoirs: plasma RNA single copy assays and beyond

Quantification of plasma HIV-1 RNA below the limit of FDA-approved assays by a single copy quantitative PCR assays (SCA) has provided significant insights into HIV-1 persistence despite potent antiretroviral therapy as well as a means to assess the impact of therapeutic strategies, such as treatment intensification, on residual viremia. In this review, we discuss insights gained from plasma HIV-1 RNA SCA and highlight the need for additional assays to characterize better the cellular and tissue reservoirs of HIV-1. Accurate, reproducible, and sensitive assays to quantify HIV-1 reservoirs, before and after therapeutic interventions, are essential tools in the quest for a cure of HIV-1 infection.

Treatment intensification has no effect on the HIV-1 central nervous system infection in patients on suppressive antiretroviral therapy

BACKGROUND

Antiretroviral treatment (ART) significantly reduces cerebrospinal fluid (CSF) HIV-1 RNA levels and residual viremia is less frequently found in CSF than in blood. However, persistent intrathecal immunoactivation is common, even after several years of ART. To investigate whether low-level CSF viremia and residual immunoactivation within the central nervous system (CNS) derive from ongoing local viral replication, we conducted a study of treatment intensification in patients on effective ART.

METHODS

Ten patients on ART with plasma HIV RNA <50 copies per milliliter for >18 months were included. Intensification was given for in total 8 weeks: 4 weeks with maraviroc or lopinavir/ritonavir (good CNS penetration), and 4 weeks with enfuvirtide (poor CNS penetration). Lumbar punctures were performed 4 weeks before, at intensification commencement, at switchover after 4 weeks, at the conclusion of, and 4 weeks after the intensification period.

RESULTS

No significant changes in HIV RNA, neopterin, β2-microglobulin, immunoglobulin G index, albumin ratio, and CD4(+) T-cell count were observed, either in CSF or blood, neither before, during, nor after the intensification periods.

CONCLUSIONS

ART intensification did not reduce residual CSF HIV RNA levels or intrathecal immunoactivation in patients on ART. These findings do not support an ongoing viral replication in CNS.

Immune and virological benefits of 10 years of permanent viral control with antiretroviral therapy

The effects of a 10-year control of HIV replication without viral blips with antiretroviral therapy were examined in progressors. CD4 cell counts did not plateau but showed a continuous increase until the 10th year. Ultrasensitive techniques showed very low plasma HIV RNA and cell-associated DNA levels. Robust memory T cell responses to HIV-p24 were higher than in 3-year treated patients and comparable to those of Elite controllers, whereas interferon-gamma-producing HIV-specific T cells were infrequent. Long-term and efficient antiretroviral therapy provides continuous benefits both on the immune system and on the HIV reservoirs.

Antiretroviral tissue kinetics: in vivo imaging using positron emission tomography

Our current knowledge on the antiviral efficacy, dosing, and toxicity of available highly active antiretroviral therapy regimens is mostly derived from plasma or blood kinetics of anti-human immunodeficiency virus (anti-HIV) drugs. However, the blood comprises only 2% of the total target cells in the body. Tissue drug levels may differ substantially from corresponding plasma levels, and drug distribution processes may be characterized by high intertissue variability, leading to suboptimal target site concentrations and the potential risk for therapeutic failures. Positron emission tomography has greatly expanded the scope of the pharmacokinetic measurements that can be performed noninvasively in animal models or humans. We have prepared [18F]FPMPA, a fluorine-18-radiolabeled analogue of tenofovir, to study antiretroviral tissue kinetics in vivo noninvasively and tested the imaging probe in rats. The biodistribution of the fluorine-18 analogue closely follows that of nonfluorinated tenofovir. Compared to that in the blood, the levels of penetration of the antiretroviral drug were found to be significantly reduced in the spleen and submandibular lymph nodes (approximately 2-fold), in the mesenteric lymph nodes and the testes (approximately 4-fold), and in the brain compartment (approximately 25-fold). Intersubject variability of the trough drug concentration (measured at 120 min) in certain tissues, like the colon (coefficient of variation, >100%), is not reflected by the intersubject variability in the blood compartment (coefficient of variation, 24%). Positron emission tomography imaging of the fluorine-18 analogue revealed the accumulation of the antiretroviral drug in the cortex of the kidneys, a potential correlate of tenofovir-induced nephrotoxicity observed in HIV-1-infected treated patients. Thus, [18F]FPMPA is a promising radiotracer for evaluation of tenofovir biodistribution under carefully controlled drug administration protocols.

Efficacy of nelfinavir-based treatment in the central nervous system of HIV-1 infected patients

We studied the HIV-1 load and nelfinavir (NFV) concentrations in cerebrospinal fluid (CSF) after long-term successful NFV-based therapy, using ultrasensitive methods of detection. 19 patients without virological failure in plasma, who had been treated with 2 nucleoside analogue reverse transcripaste inhibitors (NRTI) and NFV for a minimum of 18 months were included. HIV-RNA was determined in plasma and CSF using an ultrasensitive method (<2 copies/ml). Total and free concentrations of NFV were analysed using high liquid chromatography with UV-light detection. 12 out of 19 (63%) patients had <2 copies HIV-RNA/ml in CSF. Seven subjects ranged between 3 and 39 copies/ml, 2 of whom had a slightly higher viral load in CSF than in plasma. NFV was detected in CSF in 16 out of 18 patients analysed and was quantifiable in 8 patients, at concentrations ranging from 6 to 29 nM. There was no correlation between NFV concentration and HIV-RNA levels. Long-term therapy with NFV + 2 NRTI showed no increased rate of virological treatment failure within the central nervous system (CNS) in compliant patients, despite earlier reports of lack of NFV penetration to CNS. Using a highly sensitive method, NFV was detected and quantified in the CSF, although at low values, which could have contributed to the high anti-HIV-1 efficacy of the therapy seen in our subjects.

The effect of antiretroviral treatment of different durations in primary HIV infection

OBJECTIVES

To compare immunological, virological and clinical outcomes in persons initiating combination antiretroviral therapy (cART of different durations within 6 months of seroconversion (early treated) with those who deferred therapy (deferred group).

DESIGN

CD4 cell and HIV-RNA measurements for 'early treated' individuals following treatment cessation were compared with the corresponding ART-free period for the 'deferred' group using piecewise linear mixed models. Individuals identified during primary HIV infection were included if they seroconverted from 1st January 1996 and were at least 15 years of age at seroconversion. Those with at least 2 CD4 less than 350 cells/microl or AIDS within the first 6 months following seroconversion were excluded.

RESULTS

Of 348 'early treated' patients, 147 stopped cART following treatment for at least 6 (n = 38), more than 6-12 (n = 40) or more than 12 months (n = 69). CD4 cell loss was steeper for the first 6 months following cART cessation, but subsequent loss rate was similar to the 'deferred' group (n = 675, P = 0.26). Although those treated for more than 12 months appeared to maintain higher CD4 cell counts following cART cessation, those treated for 12 months or less had CD4 cell counts 6 months after cessation comparable to those in the 'deferred' group. There was no difference in HIV-RNA set points between the 'early' and 'deferred' groups (P = 0.57). AIDS rates were similar but death rates, mainly due to non-AIDS causes, were higher in the 'deferred' group (P = 0.05).

CONCLUSION

Transient cART, initiated within 6 months of seroconversion, seems to have no effect on viral load set point and limited beneficial effect on CD4 cell levels in individuals treated for more than 12 months. Its long-term effects remain inconclusive and need further investigation.

Early initiation of highly active antiretroviral therapy fails to reverse immunovirological abnormalities in gut-associated lymphoid tissue induced by acute HIV infection

Background

During the acute phase of HIV infection, large CD4+ T-cell depletion occurs in the gastrointestinal tract. The kinetics of CD4+ T-cell decrease and highly active antiretroviral therapy (HAART)-mediated immune reconstitution were evaluated.

Methods

Rectosigmoid colonic (RSC) biopsies and blood samples of nine patients with acute HIV infection were collected. CD4+ T-cell count, HIV RNA, intracellular HIV DNA and messenger RNA cytokine expression were evaluated before and after 6 months of HAART.

Results

All nine patients presented symptomatic retroviral infection. Early HAART was associated with a sustained and comparable reduction of HIV RNA in plasma, peripheral blood mononuclear cells (PBMCs) and RSC biopsies. HIV DNA decreased in PBMCs, but was only marginally reduced in RSC biopsies. Comparisons between reduction rates of HIV DNA in these two compartments confirmed that HIV DNA clearance was less efficient in RSC biopsies compared with PBMCs. Assessment of immunological profiles in PBMCs and RSC biopsies showed that the T-helper (Th)1-like/Th2-like ratio was sharply decreased in RSC biopsies and increased in PBMCs throughout the study period. A persistent Th2-like profile was detected in RSC biopsies. Efficient clearing of HIV DNA observed in PBMCs correlated with the establishment of a more favourable Th1-like profile.

Conclusions

A less efficient clearance of intracellular HIV DNA following early introduction of HAART is associated with persistent immunological impairment in gut-associated lymphoid tissue (GALT), which is refected by the skewed expression of cytokines in this reservoir. The present study shows that early initiation of HAART, in the short-term, is not effective in containing the establishment of HIV infection and in reversing associated immunological GALT abnormalities.

Nanoparticle-Based biobarcode amplification assay (BCA) for sensitive and early detection of human immunodeficiency type 1 capsid (p24) antigen

Nanotechnology-based techniques are being widely evaluated in medical testing and could provide a new generation of diagnostic assays due to their high degrees of sensitivity, high specificity, multiplexing capabilities, and ability to operate without enzymes. In this article, we have modified a nanoparticle-based biobarcode amplification (BCA) assay for early and sensitive detection of HIV-1 capsid (p24) antigen by using antip24 antibody-coated microplates to capture viral antigen (p24) and streptavidin-coated nanoparticle-based biobarcode DNAs for signal amplification, followed by detection using a chip-based scanometric method. The modified BCA assay exhibited a linear dose-dependent pattern within the detection range of 0.1 to 500 pg/ml and was approximately 150-fold more sensitive than conventional enzyme-linked immunosorbent assay (ELISA). No false positive results were observed in 30 HIV-1-negative samples, while all 45 HIV-1 RNA positive samples were found HIV-1 p24 antigen positive by the BCA assay. In addition, the BCA assay detected HIV-1 infection 3 days earlier than ELISA in seroconversion samples. Preliminary evaluation based on testing a small number of samples indicates that the HIV-1 p24 antigen BCA may provide a new tool for sensitive and early detection of HIV-1 p24 antigen in settings where HIV-1 RNA testing is currently not routinely performed.

HIV-1 Viral Replication below 50 Copies/ml in Patients on Antiretroviral Therapy is not associated with CD8+ T-cell Activation

Objectives

To determine if the expression of CD38 on CD8+ T-cells could be used as a marker of viral replication <50 copies/ml in peripheral blood.

Methods

In a cross-sectional study of patients attending a single HIV clinic in London, an ultra-sensitive HIV RNA viral load assay, with a limit of detection of 3 copies/ml, was used to determine HIV-1 replication in plasma in 70 patients who had sustained viral suppression <50 copies/ml by bDNA assays. Immune activation using the expression of CD38 on CD8+ T-cells was also assessed in patients on antiretroviral therapy (ART) with sustained viral suppression, individuals with persistent low-level viraemia <400 copies/ml and subjects failing ART (viral load >400 copies/ml).

Results

There was no significant difference in the percentage of CD8+CD38++ T-cells between patients with <50 copies or <3 copies/ml. Immune activation was significantly increased in patients with persistent low-level viraemia and in subjects failing ART. CD4+ T-cell counts in patients on long-term successful ART are inversely associated with CD8+ T-cell activation.

Conclusions

T-cell activation in patients on long-term successful ART is not due to residual low-level viral replication in the blood compartment of HIV-1. CD8+ T-cell activation in this patient group appears to be associated with poor CD4+ T-cell recovery.

Evolução da contagem de células T CD4+ de portadores de AIDS em contextos socialmente desiguais

Este estudo analisou a evolução da contagem de células T CD4+ em portadores de AIDS do Município do Rio de Janeiro, submetidos a esquemas anti-retrovirais altamente ativos (HAART), no Centro Municipal de Saúde (CMS) da Maré, localizado em complexo de favelas e no de Copacabana, localizado em área de elites. Imediatamente, antes de HAART, a mediana de linfócitos T CD4+ foi 181células/mm³ na Maré e 182células/mm³ em Copacabana. Após 24 semanas de HAART, a mediana alcançou 302 e 315células/mm³ nos dois CMS, respectivamente. Após HAART, os portadores de AIDS da Maré tiveram 2,8 vezes mais chances de não apresentarem resposta imunológica do que casos de Copacabana (IC95%: 1,1-7,2). Residentes em favelas da Maré tiveram 3,7 mais chances de não apresentarem resposta imunológica do que não residentes em favelas de Copacabana (IC95%: 1,2-11,5). Homens da Maré tiveram 4,4 mais chances de não apresentarem resposta imunológica do que os de Copacabana (IC95%: 1,1-18,2). Resultados sugerem pior prognóstico e maior letalidade para portadores de AIDS residentes em favelas, independente do acesso a HAART.

When to start antiretroviral therapy

The current literature is controversial in providing evidence to determine the optimal time to initiate therapy among patients with HIV. However, there is evidence that initiating early treatment might provide benefits by treating primary HIV infection, preserving normal immune function, suppressing HIV viral replication, deferring clinical progression, and reducing HIV transmission. The biggest challenges in initiating treatment early are issues related with long-term management, including toxicities, adherence, and drug resistance. However, the availability of superior new antiretroviral drugs and simplified regimens, the development of effective treatment strategy, and further improvement of adherence through directly observed treatment are addressing the issues and changing the balance towards earlier treatment.

Experimental approaches to the study of HIV-1 latency

Viral latency is a reversibly non-productive state of infection that allows some viruses to evade host immune responses. As a consequence of its tropism for activated CD4(+) T cells, HIV-1 can establish latent infection in resting memory CD4(+) T cells, which are generated when activated CD4(+) T cells return to a quiescent state. Latent HIV-1 persists as a stably integrated but transcriptionally silent provirus. In this state, the virus is unaffected by immune responses or antiretroviral drugs, and this latent reservoir in resting CD4(+) T cells is a major barrier to curing the infection. Unfortunately, there is no simple assay to measure the number of latently infected cells in a patient, nor is there an entirely representative in vitro model in which to explore the molecular mechanisms of latency. This Review will consider current approaches to the analysis of HIV-1 latency both in vivo and in vitro.

Considerations in the design of randomized controlled trials evaluating the optimal time to initiate antiretroviral therapy in previously untreated HIV-1-infected patients

PURPOSE OF REVIEW

This paper addresses design issues around 'when to start' trials in adults and children and in chronic and acute HIV infection. Issues for young children treated soon after birth and recently seroconverting adults differ, and are also discussed.

RECENT FINDINGS

No trials have been published addressing this question for combination antiretroviral therapy in chronic HIV infection, and the evidence base for guidelines has largely been derived from observational studies. The biases inherent in observational data and recent results from the adult SMART trial may have moved the level of equipoise from 'unstable certainty' (mitigating against randomization) to a renewed call for a very large clinical endpoint trial of when to start therapy in the era of highly active antiretroviral therapy. Older children could also be enrolled in such a trial, as the predictive value of CD4 cell count values in children over 5 years and young adults. In acute infection, ongoing trials in adults and children is similar considering strategies of early short-term combination antiretroviral therapy compared with deferred therapy. Although not strictly 'when to start trials', these approaches could reduce life-long exposure to antiretroviral therapy while maintaining clinical and immunological well being.

SUMMARY

Issues in the design of a future randomized trial of when to start antiretroviral therapy in chronic HIV infected adults and older children are discussed, while the role of early limited therapy in primary infection awaits results of ongoing trials.

Cerebrospinal Fluid Viral Loads Reach Less than 2 Copies/ML in HIV-1-Infected Patients with Effective Antiretroviral Therapy

Background

A low-grade persisting viraemia despite long-term treatment with highly active antiretroviral therapy (HAART) has previously been demonstrated in HIV-1-infected patients. Whether ongoing viral replication also could be detected in cerebrospinal fluid (CSF) in those circumstances has not been studied before.

Methods

Paired CSF and blood samples from 13 neurologically asymptomatic HIV-1-infected patients on stable HAART were analysed regarding HIV-1 RNA, by using a PCR assay with a detection limit of 2 copies/ml.

Results

All 13 patients had HIV-1 RNA <2 copies/ml in CSF, compared with 8/13 in plasma.

Conclusion

We could not demonstrate any persistent viral replication in the CSF of neurologically asymptomatic HIV-1-infected patients on effective HAART, rendering it unlikely that CSF acts as a viral reservoir in this category of patients.

Primary human immunodeficiency virus type 1 infection: clinical, virological and immunological characteristics of 75 patients (1997-2003)

OBJECTIVES

To describe the epidemiological and clinical characteristics and the evolution of a cohort of patients with primary HIV-1 infection from the Barcelona area.

METHODS

Prospective cohort study of HIV-infected patients diagnosed with primary HIV infection in a tertiary hospital in Barcelona (Spain) from 1997 through 2003. Descriptive analysis of epidemiological and clinical characteristics and effect of highly active antiretroviral treatment (HAART) on outcome.

RESULTS

A total of 75 patients were diagnosed, accounting for 2.9% of the total of newly diagnosed HIV patients during the same time period. Eighty-one percent of the patients were males and the median age was 30 years (IQR 26-38). The most frequent transmission route was homosexual (72%), followed by heterosexual (17%) and intravenous drug abuse (11%). Seventy-seven percent of patients presented symptoms, the most frequent being fever (98%), asthenia (86%), arthralgia-myalgia (65%), lymphadenopathy (55%), night sweats (48%) and rash. Sixty-five percent started HAART, although the proportion of patients that received HAART decreased from 79% during the period 1997-2000 to 49% during the period 2001-2003 (p < 0.01). After a median follow-up of 37 months (IQR 26-66), one patient died and eight cases were lost to follow-up. The patients who did not receive HAART had a higher probability of immunological or clinical deterioration during the follow-up when compared to the group that received HAART (42.3% versus 12.3%; p < 0.001). In treated patients, dyslipidemia and lipodystrophy were diagnosed in 58% and 37% of cases, respectively.

CONCLUSIONS

Primary HIV-1 infection was diagnosed more frequently in homosexual males, and its clinical characteristics were similar to those observed in previous studies. HAART given during primary HIV infection was effective, but was associated with a high percentage of adverse effects.

Viral and latent reservoir persistence in HIV-1-infected patients on therapy

Despite many years of potent antiretroviral therapy, latently infected cells and low levels of plasma virus have been found to persist in HIV-infected patients. The factors influencing this persistence and their relative contributions have not been fully elucidated and remain controversial. Here, we address these issues by developing and employing a simple, but mechanistic viral dynamics model. The model has two novel features. First, it assumes that latently infected T cells can undergo bystander proliferation without transitioning into active viral production. Second, it assumes that the rate of latent cell activation decreases with time on antiretroviral therapy due to the activation and subsequent loss of latently infected cells specific for common antigens, leaving behind cells that are successively less frequently activated. Using the model, we examined the quantitative contributions of T cell bystander proliferation, latent cell activation, and ongoing viral replication to the stability of the latent reservoir and persisting low-level viremia. Not surprisingly, proliferation of latently infected cells helped maintain the latent reservoir in spite of loss of latent infected cells through activation and death, and affected viral dynamics to an extent that depended on the magnitude of latent cell activation. In the limit of zero latent cell activation, the latent cell pool and viral load became uncoupled. However, as the activation rate increased, the plasma viral load could be maintained without depleting the latent reservoir, even in the absence of viral replication. The influence of ongoing viral replication on the latent reservoir remained insignificant for drug efficacies above the "critical efficacy" irrespective of the activation rate. However, for lower drug efficacies viral replication enabled the stable maintenance of both the latent reservoir and the virus. Our model and analysis methods provide a quantitative and qualitative framework for probing how different viral and host factors contribute to the dynamics of the latent reservoir and the virus, offering new insights into the principal determinants of their persistence.

Residual human immunodeficiency virus type 1 viremia in some patients on antiretroviral therapy is dominated by a small number of invariant clones rarely found in circulating CD4+ T cells

Antiretroviral therapy can reduce human immunodeficiency virus type 1 (HIV-1) viremia to below the detection limit of ultrasensitive clinical assays (50 copies of HIV-1 RNA/ml). However, latent HIV-1 persists in resting CD4+ T cells, and low residual levels of free virus are found in the plasma. Limited characterization of this residual viremia has been done because of the low number of virions per sample. Using intensive sampling, we analyzed residual viremia and compared these viruses to latent proviruses in resting CD4+ T cells in peripheral blood. For each patient, we found some viruses in the plasma that were identical to viruses in resting CD4+ T cells by pol gene sequencing. However, in a majority of patients, the most common viruses in the plasma were rarely found in resting CD4+ T cells even when the resting cell compartment was analyzed with assays that detect replication-competent viruses. Despite the large diversity of pol sequences in resting CD4+ T cells, the residual viremia was dominated by a homogeneous population of viruses with identical pol sequences. In the most extensively studied case, a predominant plasma sequence was also found in analysis of the env gene, and linkage by long-distance reverse transcriptase PCR established that these predominant plasma sequences represented a single predominant plasma virus clone. The predominant plasma clones were released for months to years without evident sequence change. Thus, in some patients on antiretroviral therapy, the major mechanism for residual viremia involves prolonged production of a small number of viral clones without evident evolution, possibly by cells other than circulating CD4+ T cells. The sequences have been deposited in GenBank. The accession numbers are DQ 391282 to DQ 391351 (for env) and DQ 391352 to DQ 392955 (for RT).

HIV-1-specific CD4+ T cell responses in chronically HIV-1 infected blippers on antiretroviral therapy in relation to viral replication following treatment interruption

The impact of transient viral load blips on anti-HIV-1 immune responses and on HIV-1 rebound following treatment interruption (TI) is not known. Clinical and immunological parameters were measured during 40 weeks of antiretroviral therapy (ART) and following TI in an observational cohort of 16 chronically HIV-1-infected subjects with or without observed viral load blips during ART. During therapy, blips in seven subjects were associated with higher anti-HIV-1 (p24) CD4+ T cell lymphoproliferative responses (p = 0.04), without a significant difference in T cell activation or total anti-HIV-1 CD8+ T cell interferon-gamma (IFN-gamma) responses when compared to nine matched non-blippers. Therapy interruption resulted in a significantly higher viral rebound in blippers by 8 week despite retention of higher lymphoproliferative p24 responses (p = 0.01) and a rise in CD3+ T cell activation (p = 0.04) and anti-HIV-1 CD8+ T cell responses in blippers by week 4 when compared to non-blippers. Past week 4 of interruption, therapy re-initiation criteria were also met by a higher frequency in blippers by week 14 (p < 0.04) with no difference between groups by week 24. These data support that blippers have higher anti-HIV lymphoproliferative responses while on ART but experience equal to higher viral rebound as compared to matched non-blippers upon TI.

Early induction of leukemia inhibitor factor (LIF) in acute HIV-1 infection

BACKGROUND

Leukemia inhibitor factor (LIF) is thought to play a substantial role in protecting CD4 T cells in lymphoid tissues (LT) from infection by HIV-1.

OBJECTIVE

To investigate whether primary HIV-1 infected subjects with sustained virological control (< 1000 HIV-1 RNA copies/ml plasma) post-cessation antiretroviral therapy (ART) had a higher initial LIF response during primary HIV-1 infection (PHI) as compared with those individuals who did not achieve a similar control (> 9000 HIV-1 RNA copies/ml plasma) of HIV-1 replication.

MATERIAL AND METHODS

Consecutively obtained HIV plasma samples were collected from primary HIV-1 infected subjects. A group of acutely Epstein-Barr virus-infected subjects and a group of HIV-1-seronegative healthy individuals served as controls. All samples were tested by ELISA for LIF and sgp130, the soluble form of LIF's signalling receptor.

RESULTS

LIF and sgp130 plasma levels were significantly increased in primary HIV-1-infected subjects as compared with HIV-1-seronegative controls. Peak plasma levels of LIF occurred during the first week of PHI whereas sgp130 peaked between 2 and 4 weeks after the onset of PHI. Furthermore a positive correlation was found between viral load and plasma levels of LIF during PHI. Both LIF and sgp130 plasma concentrations were significantly lower during the viral rebound phase after treatment interruption as compared with the PHI phase.

CONCLUSIONS

LIF induction occurred in the initial stages of viral dissemination during PHI. It may be a part of the virally induced generalized pro-inflammatory response. LIF levels at PHI did not predict low levels of HIV viraemia after discontinuation of ART. LIF was not increased following ART interruption in this early treated population.

HIV-1 intermittent viraemia in patients treated by non-nucleoside reverse transcriptase inhibitor-based regimen

BACKGROUND

It has been demonstrated that, in patients treated by protease-inhibitor-based regimen, intermittent viraemia occurred frequently and was associated with higher concentrations of residual replication but not with virological failure. Risk factors associated with intermittent viraemia and its impact in patients treated by non-nucleoside-reverse-transcriptase-inhibitor-based (NNRTI) regimen need to be evaluated.

METHODS

We analyzed the occurrence of blips (one HIV-1 RNA > 50 copies/ml with a subsequent value < 50 copies/ml), the level of these blips (between 3 and 50 copies/ml) and their effect on CD4 cell count and the occurrence of virological failure in 43 patients with stable suppression of HIV-1 plasma viraemia (< 50 copies/ml) under NNRTI-based therapy.

RESULTS

Eight out of 43 patients had one episode of blips during the follow-up (median = 350 copies/ml). Comparing patients with and without blips, the median level of HIV-1 RNA at baseline was 7.5 versus 3 copies/ml (P = 0.008), respectively. Patients with blips had a significantly lower CD4 cell count after 12 and 18 months than the others. Plasma concentrations of NNRTI before, during, and after the blips were adequate. In addition, the occurrence of blips was not associated with virological failure.

CONCLUSION

These results suggest that blips may reflect ongoing viraemia of below 50 copies/ml and can impair the CD4 cell count recovery under an NNRTI regimen. The impairment of CD4 cell count recovery seems to be affected more by the occurrence of blips than by the level of viraemia (< 50 copies/ml) itself. Nevertheless, despite a tight genetic barrier for resistance with NNRTI drugs, no virologic failure occurred during the follow-up.

Clinical, immunological and virological evolution in patients with CD4 T-cell count above 500/mm3: is there a benefit to treat with highly active antiretroviral therapy (HAART)?

To assess the clinical, immunological and virological evolution in HIV-1 infected patients with CD4 T-cell count above 500/mm3, a historical cohort of 202 untreated and 96 patients treated with HAART was longitudinally studied (median follow-up 36 months). Fourteen untreated and 2 treated patients experienced clinical progression (p = 0.09). The difference between baseline CD4 T-cell count and after 3 years, was -240/mm3 in the untreated group +19/mm3 in the HAART group (p < 10(-3)). A better immunological outcome was significantly associated with a HIV sexual contamination (p = 0.01), HAART (p = 0.01), high baseline CD4 T-cell count (p < 10(-3)) and low baseline HIV viral load (p = 0.01). In the HAART group, the incidence rate of antiretroviral modification due to tolerance difficulties was 0.23+/-0.36/patient year. A sustained undetectable HIV viral load was correlated with a low baseline HIV viral load (p = 0.003) and to be antiretroviral naive (p < 10(-3)). Thus, HAART provide a better immunological outcome in patients with high CD4 T-cell count. However, the CD4 decay slope after 3 years, the risk of therapeutic side-effects and the low risk of clinical progression do not support systematic treatment of those patients.

Dynamics of intermittent viremia during highly active antiretroviral therapy in patients who initiate therapy during chronic versus acute and early human immunodeficiency virus type 1 infection

The meaning of viral blips in human immunodeficiency virus type 1 (HIV-1)-infected patients treated with seemingly effective highly active antiretroviral therapy (HAART) is still controversial and under investigation. Blips might represent low-level ongoing viral replication in the presence of drug or simply release of virions from the latent reservoir. Patients treated early during HIV-1 infection are more likely to have a lower total body viral burden, a homogenous viral population, and preserved HIV-1-specific immune responses. Consequently, viral blips may be less frequent in them than in patients treated during chronic infection. To test this hypothesis, we compared the occurrence of viral blips in 76 acutely infected patients (primary HIV infection [PHI] group) who started therapy within 6 months of the onset of symptoms with that in 47 patients who started HAART therapy during chronic infection (chronic HIV infection [CHI] group). Viral blip frequency was approximately twofold higher in CHI patients (0.122 +/- 0.12/viral load [VL] sample, mean +/- standard deviation) than in PHI patients (0.066 +/- 0.09/VL sample). However, in both groups, viral blip frequency did not increase with longer periods of observation. Also, no difference in viral blip frequency was observed between treatment subgroups, and the occurrence of a blip was not associated with a recent change in CD4(+) T-cell count. Finally, in PHI patients the VL set point was a significant predictor of blip frequency during treatment.

Evaluation of nevirapine and/or hydroxyurea with nucleoside reverse transcriptase inhibitors in treatment-naive HIV-1-infected subjects

OBJECTIVE

To examine the effect of adding nevirapine (NVP) and/or hydroxyurea (HU) to a triple nucleoside analogue reverse transcriptase inhibitor (NRTI) regimen in terms of efficacy and tolerability.

METHODS

: HIV-1-infected, treatment-naive adults were randomized, using a factorial design, to add NVP and/or HU to the triple NRTI backbone of zidovudine plus lamivudine plus abacavir. Primary endpoint was treatment failure, defined as having plasma HIV RNA levels > 50 copies/ml after week 24, or discontinuation of randomized treatment. Follow-up was 72 weeks.

RESULTS

For the 229 subjects, median plasma HIV-1 RNA was 4.61 log10 copies/ml and median CD4 cell count was 269 x 10 cells/l. NVP users reached plasma HIV-1 RNA < 50 copies/ml more rapidly than subjects using no NVP (log-rank test; P = 0.011). In the as-treated analysis, 21.6% of subjects using NVP versus 48.8% using no NVP reached the primary endpoint (P = 0.013). In the intent-to-treat analysis, 83.3% of subjects using HU versus 73.0% using no HU experienced treatment failure (P = 0.060), while no difference was observed in the as-treated analysis (34.5 versus 36.7%). Differences in the intent-to-treat analysis were accounted for by toxicity: 52.6% of subjects using HU experienced toxicity leading to discontinuation of randomized treatment versus 28.7% of subjects using no HU.

CONCLUSION

The use of NVP in addition to a triple NRTI regimen improved both short- and long-term antiretroviral efficacy. The use of HU significantly contributed to treatment failure because of toxicity.

Determinants of long-term highly active antiretroviral treatment efficacy

OBJECTIVES

Predictors of the efficacy of highly active antiretroviral therapy (HAART) have been investigated in several studies. To increase current knowledge, the study aimed to acquire comprehensive data over an extended observation time, to obtain information on possible performance differences among individual drugs, and to identify factors with influence on the initial response to a HAART regimen and the sustainability of the response.

METHODS

The data were obtained from a prospective, single University Medical School HIV cohort. Clinical, laboratory, and treatment parameters for 475 patients were collected over 4.5 years. HAART efficacy was determined by analysis of variance and multivariate survival analysis.

RESULTS

The overall initial complete response (CR) (<500 HIV-1 RNA copies/mL) was 76.3%. Use of indinavir [odds ratio (OR)=2.747, P=0.0009] and the number of new nucleoside reverse transcriptase inhibitors (NRTIs) (OR=1.862, P=0.0017) were positively associated with CR, while initial peripheral blood HIV RNA concentration (OR=0.383, P<0.0001), use of saquinavir hard gel capsules (OR=0.531, P=0.0302), the number of successive HAART regimens (OR=0.631, P<0.0001), and the number of previously used NRTIs (OR=0.728, P=0.0081) were negatively associated with CR. Sustainability of CR was positively correlated with use of indinavir [hazard ratio of relapse (HR)=0.255, P<0.0001] and haemoglobin levels (HR=0.873, P=0.0124), but negatively correlated with initial HIV RNA concentration (HR=1.273, P=0.0003) and the number of previously used NRTIs (HR=1.587, P<0.0001). A higher number of consecutive HAART regimens was associated with a markedly reduced CR, but with only a slightly higher risk of relapse.

CONCLUSIONS

The initial response to HAART, as well as long-term efficacy, depends strongly on a few fundamental parameters that can easily be assessed in a clinical setting. There is a need for effective suppression of HIV replication over decades, and these factors should be considered early in treatment planning to identify patients with an unfavourable profile of risk factors for treatment failure.

A Randomized Trial Comparing Initial Haart Regimens of Nelfinavir/Nevirapine and Ritonavir/Saquinavir in Combination with Two Nucleoside Reverse Transcriptase Inhibitors

Background

A triple-class HAART regimen may be associated with a better virological effect than conventional regimens, but may also lead to toxicity and more profound resistance.

Methods

Randomized, controlled, open-label trial of 233 protease inhibitor- and non-nucleoside reverse transcriptase inhibitor-naive HIV-infected patients allocated to a regimen of nelfinavir and nevirapine (1250/200 mg twice daily; n=118) or ritonavir and saquinavir (400/400 mg twice daily; n=115), both in combination with two nucleoside reverse transcriptase inhibitors. The primary end-point was HIV RNA ≤20 copies/ml after 48 weeks (missing value=failure). Patients remained under follow-up also in case of switch from the randomized therapy.

Results

At baseline, the median CD4 cell counts were 126 (range: 0–942) (nelfinavir/nevirapine) and 150 (0–642) (ritonavir/saquinavir) cells/mm3, and HIV RNA measurements 5.0 copies/ml (1.3–6.4) in both groups. A total of 102 (86%) and 101 (88%) were antiretroviral-naive. Within 48 weeks, 35 and 44% discontinued randomized therapy; P=0.13. Of these, 80 and 73% switched therapy due to adverse events; P=0.99. At week 48, 69 and 56%, respectively, had a HIV RNA ≤20 copies/ml; P=0.037.

Conclusion

A regimen of nelfinavir/nevirapine had a favourable virological effect and tolerability over a 48-week period compared with ritonavir/saquinavir, when administered in combination with two nucleoside reverse transcriptase inhibitors. However, more extensive follow-up is required to determine the long-term consequences of triple class HAART regimens, including the development of broad drug resistance.

Rapid whole-blood finger-stick test for HIV antibody: performance and acceptability among women in northern Thailand

Although use of rapid HIV antibody tests of finger-stick blood specimens could expand voluntary counseling and testing in areas where fear of venipuncture and delays in learning test results are barriers, there is little information on performance and acceptability of these tests in Asia. We used the Hema. Strip HIV-1/2 test (Saliva Diagnostic Systems, Vancouver, WA) in a prospective cohort study of HIV seroincidence among women in northern Thailand from 1998 to 1999. Nurses obtained whole-blood specimens by finger-stick testing and provided test results and counseling at each visit. Acceptability of the rapid test was assessed at the first 6-month follow-up visit. HIV-1 seroprevalence among the 804 women screened at enrollment was 3.1%. Positive rapid test results from 25 women were confirmed by enzyme immunoassay and Western blot analysis using serum obtained by venipuncture. Of the 741 women who returned for follow-up, 56% preferred specimen collection by finger-stick testing to venipuncture, 80% preferred immediate rather than delayed test results, 79% preferred the rapid test method to typical testing methods, and 97% were satisfied with the test method used. Results from this study demonstrate the utility and acceptability of the rapid finger-stick test for HIV antibody among women in northern Thailand.

HIV-1 RNA and viral load

Viral load monitoring has become the standard of care in clinical practice to assess risk for disease progression and to monitor treatment response. Furthermore, viral load monitoring has contributed greatly to the understanding of HIV disease pathogenesis and response to various antiretroviral regimens, and has broadened its applications to include blood bank screening. The assays that are currently available are more sensitive, precise, and robust. There is now a better understanding of their limitations and the clinical scenarios and assay performance issues that result in variations of viral load results.

Greater reversal of CD4+ cell abnormalities and viral load reduction after initiation of antiretroviral therapy with zidovudine, lamivudine, and nelfinavir before complete HIV type 1 seroconversion

In a prospective open-label study, 41 male subjects received nelfinavir, zidovudine, and lamivudine stratified as either: early stage (ES; negative/indeterminate Western blot; n = 19) or late stage (LS; positive Western blot; n = 22) primary HIV-1 infection. Despite higher median baseline HIV-1 RNA levels and lower CD4(+) cell numbers in the ES subjects, a significantly greater decline in viral load (-3.46 vs. -2.83 log(10) copies/ml; p = 0.023) and increase in CD4(+) cell number (+85 vs. +41 cells/month increase, p = 0.01) were observed over the first 3 months of therapy such that both groups had comparable results at 1 year. The proportion with HIV-1 RNA < 50 copies/mL at 1 year was similar (9 of 19 ES subjects and 11 of 22 LS subjects by intention-to-treat analysis). Memory CD4(+) cell numbers, and activated CD4(+) percentages, were also significantly improved in ES subjects. Despite poorer prognostic markers at baseline ES subjects achieved responses similar to those of LS subjects after 1 year of treatment.

HIV-1 reservoirs

In most infected individuals, HIV-1 replicates high levels throughout the duration of infection, including the clinically quiescent phase of disease. The level of this active viral replication correlates directly with disease progression and survival. The advent of combination therapeutics for HIV-1 (i.e., highly active antiretroviral therapy [HAART]) has led to dramatic reductions in viral replication in vivo and morbidity and mortality, at least in the developed world.

The challenge of viral reservoirs in HIV-1 infection

A viral reservoir is a cell type or anatomical site in association with which a replication-competent form of the virus accumulates and persists with more stable kinetic properties than the main pool of actively replicating virus. This article reviews several cell types and anatomical sites proposed as potential reservoirs for HIV-1. It is now clear that HIV-1 persists in a small reservoir of latently infected resting memory CD4(+) T cells, which shows minimal decay even in patients on highly active antiretroviral therapy (HAART). The persistence of virus in this reservoir is consistent with the biology of these cells and the long-term persistence of immunologic memory. The viral replication that continues in patients on suppressive HAART may also contribute to the stability of this reservoir. There may be other reservoirs, but the latent reservoir in resting CD4(+) T cells appears to be sufficient to guarantee lifetime persistence of HIV-1 in the majority of patients on current HAART regimens, and unless new approaches are developed, eradication will not be possible. The clinical implications of this and other HIV-1 reservoirs are discussed.

On the use of magnitude of reduction in HIV-1 RNA in clinical trials: statistical analysis and potential biases

Clinical trials endpoints based on magnitude of reduction in HIV-1 RNA levels provide an important complement to endpoints based on either virologic failure or a proportion of patients having HIV-1 RNA levels below a threshold value. However, reductions in HIV-1 RNA often are not completely observed, because many patients have HIV-1 RNA levels below the limit of quantification at the primary follow-up visit. The crude method of analyzing such data is to define all HIV-1 RNA levels that fall below the limit of quantification as being equal to that limit of quantification. This method is widely used even though the underestimation inherent in such a method may also lead to underestimation of treatment difference in terms of HIV-1 RNA reduction. Analyses based on Kaplan-Meier method and censored regression can be used to estimate such a reduction. When a high percentage of patients have HIV-1 RNA levels below the limit of quantification at the time of primary follow-up, which corresponds to censored observations, the Kaplan-Meier method does not always provide an estimate of the median HIV-1 RNA reduction. We discuss a statistical method to provide lower and upper limits of such median reduction or of other percentiles of reduction. We found that when the percentage of censoring is high, the censored method may overestimate the HIV-1 RNA reduction and then may also overestimate the treatment difference. Although the censored method is preferable to the crude method, when the level of censoring is high, we suggest computation of the upper and lower limits either to provide a range of potential values of HIV-1 RNA reduction or to detect overestimation by the censored method.

HIV-1 therapeutic vaccines

In this review, we address recent advances in the understanding of the pathogenesis of human immunodeficiency type 1 virus infection, which have provided the rationale for present trials of therapeutic vaccines. We shall relate this work to lessons of the past few years both in the use of highly active antiretroviral therapy to attempt eradication of the HIV virus, and in the study of treatment interruptions.

Improved long-term suppression of HIV-1 replication with a triple-class multidrug regimen compared with standard of care antiretroviral therapy

BACKGROUND

The treatment of HIV-1-infected patients with triple-drug combination therapy results in profound suppression of viral replication. In most therapy-naive patients plasma HIV-1-RNA levels (pVL) drop below the lower limit of quantification (LLQ) of currently used assays. In a large percentage of such patients, more sensitive assays provide evidence of residual viral replication. The question is whether more potent therapy can further suppress this residual replication.

METHODS

Thirty control patients who, using very strict criteria, had not experienced virological failure during 3 years of standard therapy, were compared with 10 patients treated with a five-drug regimen, consisting of three different classes of antiretroviral drugs (alternative multidrug regimen). A modified ultrasensitive assay with an LLQ of 5 copies/ml was used to re-test plasma obtained at week 48 and at three timepoints at and around week 144.

RESULTS

At weeks 48 and 144 pVL could be quantified significantly more frequently in control patients than in patients using the alternative multidrug regimen (week 48: 42 versus 0% with quantifiable pVL, P = 0.017; week 144: 60 versus 14% with at least one quantifiable pVL, P = 0.036, respectively). A low baseline CD4T cell count was predictive of quantifiable pVL in control patients, but not in alternative multidrug patients.

CONCLUSION

This proof-of-principle study demonstrates that the use of an alternative multidrug regimen results in stronger long-term suppression of pVL compared with clinically successful treatment with standard therapy.

Predictors of virological rebound in HIV-1-infected patients initiating a protease inhibitor-containing regimen

OBJECTIVE

To study the predictors of virological rebound in patients having early virological response to protease inhibitor (PI)-containing regimen.

DESIGN AND METHODS

APROCO cohort study prospectively enrolled 1283 HIV-infected patients starting a PI-containing regimen in 1997-1999. Adherence to therapy was measured with self-administered questionnaires after 4 months of therapy (M4). Virological rebound was defined as a viral load (VL) > 500 copies/ml in patients having early virological response, defined as a VL < 500 copies/ml at M4. Predictors of time to virological rebound were studied with multivariate proportional hazards model.

RESULTS

During a median follow-up of 20 months, virological rebound was observed in 32% of the 830 patients with early virological response. Virological rebound was more frequent when patients had received previous antiretroviral treatment [adjusted hazards ratio (HR) = 2.4; P < 0.0001], were younger (HR = 1.4 per each 10 years younger; P < 0.0001), had baseline CD4 cell count < 500 x 106/l (HR = 2.3; P < 0.001), had higher baseline VL (HR = 1.4 per each log10 copies/ml higher; P < 0.001), reported low adherence to therapy at M4 (HR = 2.1; P < 0.001) or had stopped PI at M4 (HR = 1.7; P = 0.04).

CONCLUSION

Initiation of treatment at a stage of preserved immunity is associated with a more durable virological response under protease inhibitor. Every effort should be made to monitor and strengthen adherence to therapy, even in patients having early virological response.