Comparison of viro-immunological marker changes between HIV-1 and HIV-2-infected patients in France

HIV-1 p17 matrix protein enhances type I interferon responses through the p17-OLA1-STING axis

Stimulator of IFN genes (STING; also known as STING1) is an important adaptor protein for detecting cytosolic double-stranded DNA, which can come from HIV infection. Several HIV proteins, such as p6, Vpx and Vif, can influence STING-mediated innate immunity, but the function of p17 is still unknown. In this study, we find that HIV-1 p17, but not HIV-2 p17 or SIV p17, promotes STING signaling induced by cyclic GMP-AMP (cGAMP) treatment. Mechanistically, HIV-1 p17 binds to Obg-like ATPase 1 (OLA1) and inhibits the regulation of STING by OLA1. Here, OLA1 interacts with STING and inhibits the translocation and phosphorylation of STING upon cGAMP stimulation. Furthermore, compared with HIV-2 and SIV, the ATPase and GTPase activities of OLA1 are only promoted by HIV-1 p17. Our study shows that the p17 of HIV-1, but not HIV-2 or SIV, promotes STING-mediated innate immunity by interfering the interaction between OLA1 and STING, thus providing a new clue for specific immune activation of HIV-1.

The HIV-2 OGH double reporter virus shows that HIV-2 is less cytotoxic and less sensitive to reactivation from latency than HIV-1 in cell culture

A better understanding of HIV-1 latency is a research priority in HIV cure research. Conversely, little is known about the latency characteristics of HIV-2, the closely related human lentivirus. Though both viruses cause AIDS, HIV-2 infection progresses more slowly with significantly lower viral loads, even when corrected for CD4+ T cell counts. Hence a direct comparison of latency characteristics between HIV-1 and HIV-2 could provide important clues towards a functional cure. Transduction of SupT1 cells with single-round HIV-1 and HIV-2 viruses with an enhanced green fluorescent protein (eGFP) reporter showed higher levels of eGFP expression for HIV-2 than HIV-1, while HIV-1 expression appeared more cytotoxic. To compare HIV-1 and HIV-2 gene expression, latency and reactivation in more detail, we have generated HIV-2 OGH, a replication deficient, near full- length, double reporter virus that discriminates latently and productively infected cells in cell culture. This construct is based on HIV-1 OGH, and to our knowledge, first of its kind for HIV-2. Using this construct we have observed a higher eGFP expression for HIV-2, but higher losses of HIV-1 transduced cells in SupT1 and Jurkat cells and a reduced sensitivity of HIV-2 for reactivation with TNF-α. In addition, we have analysed HIV-2 integration sites and their epigenetic environment. HIV-1 and HIV-2 share a preference for actively transcribed genes in gene-dense regions and favor active chromatin marks while disfavoring methylation markers associated with heterochromatin. In conclusion the HIV-2 OGH construct provides an interesting tool for studying HIV-2 expression, latency and reactivation. As simian immunodeficiency virus (SIV) and HIV-2 have been proposed to model a functional HIV cure, a better understanding of the mechanisms governing HIV-2 and SIV latency will be important to move forward. Further research is needed to investigate if HIV-2 uses similar mechanisms as HIV-1 to achieve its integration site selectivity.

Novel assays to investigate the mechanisms of latent infection with HIV-2

Although there have been great advancements in the field of HIV treatment and prevention, there is no cure. There are two types of HIV: HIV-1 and HIV-2. In addition to genetic differences between the two types of HIV, HIV-2 infection causes a slower disease progression, and the rate of new HIV-2 infections has dramatically decreased since 2003. Like HIV-1, HIV-2 is capable of establishing latent infection in CD4+ T cells, thereby allowing the virus to evade viral cytopathic effects and detection by the immune system. The mechanisms underlying HIV latency are not fully understood, rendering this a significant barrier to development of a cure. Using RT-ddPCR, we previously demonstrated that latent infection with HIV-1 may be due to blocks to HIV transcriptional elongation, distal transcription/polyadenylation, and multiple splicing. In this study, we describe the development of seven highly-specific RT-ddPCR assays for HIV-2 that can be applied to the study of HIV-2 infections and latency. We designed and validated seven assays targeting different HIV-2 RNA regions along the genome that can be used to measure the degree of progression through different blocks to HIV-2 transcription and splicing. Given that HIV-2 is vastly understudied relative to HIV-1 and that it can be considered a model of a less virulent infection, application of these assays to studies of HIV-2 latency may inform new therapies for HIV-2, HIV-1, and other retroviruses.

HIV-2 Neutralization Sensitivity in Relation to Co-Receptor Entry Pathways and Env Motifs

HIV-2, compared to HIV-1, elicits potent and broadly neutralizing antibodies, and uses a broad range of co-receptors. However, both sensitivity to neutralization and breadth of co-receptor use varies between HIV-2 isolates, and the molecular background is still not fully understood. Thus, in the current study, we have deciphered relationships between HIV-2 neutralization sensitivity, co-receptor use and viral envelope glycoprotein (Env) molecular motifs. A panel of primary HIV-2 isolates, with predefined use of co-receptors, was assessed for neutralization sensitivity using a set of HIV-2 Env-directed monoclonal antibodies and co-receptor indicator cell lines. Neutralization sensitivity of the isolates was analysed in relation target cell co-receptor expression, in addition to amino acid motifs and predicted structures of Env regions. Results showed that HIV-2 isolates were more resistant to neutralizing antibodies when entering target cells via the alternative co-receptor GPR15, as compared to CCR5. A similar pattern was noted for isolates using the alternative co-receptor CXCR6. Sensitivity to neutralizing antibodies appeared also to be linked to specific Env motifs in V1/V2 and C3 regions. Our findings suggest that HIV-2 sensitivity to neutralization depends both on which co-receptor is used for cell entry and on specific Env motifs. This study highlights the multifactorial mechanisms behind HIV-2 neutralization sensitivity.

Lymphoma in HIV-2-infected patients in combination antiretroviral therapy era

OBJECTIVE

To describe lymphoma in HIV-2-infected patients and compare their characteristics with lymphoma in HIV-1-infected patients.

DESIGN

Ancillary analysis from a single center prospective cohort of HIV-lymphoma.

METHODS

We report on 16 patients with HIV-2-lymphoma diagnosed after 1996 and included in a prospective cohort of HIV lymphoma. Five additional HIV-2-infected patients coinfected with HIV-1 or/and HTLV-I (6 lymphomas) are separately reported. The incidence of lymphoma in HIV-2-infected patients was evaluated in the French multicentric HIV-2 cohort.

RESULTS

Incidence of lymphoma in the French HIV-2 cohort was estimated as 0.6/1000 patient-years. In our series, the median CD4+ cell count was 166 × 106/l at the time of lymphoma diagnosis and 50% of patients had undetectable plasma HIV-2-RNA. Lymphomas were non-Hodgkin lymphoma (n = 12) and classical Hodgkin lymphoma (n = 4). Similarly to HIV-1-lymphoma, clinical presentation was aggressive in most cases. All but one patient received intensive chemotherapy. Complete remission was achieved in 13 cases and 1 patient relapsed. The overall survival was not statistically different from that observed in patients with HIV-1 lymphoma. The six additional lymphomas observed in five HIV-2-infected patients coinfected with HIV-1 or/and HTLV-I presented with similar clinical presentation but worse prognosis.

CONCLUSION

Despite the lower pathogenicity of HIV-2, the risk of developing lymphoma seems to be close to that observed in HIV-1 population with similar lymphoma characteristics. Compared with HIV-1, HIV-2-infected patients developed lymphoma later in their life but at a similar CD4+ cell count level.

Human Immunodeficiency Virus Type 2: The Neglected Threat

West Africa has the highest prevalence of human immunodeficiency virus (HIV)-2 infection in the world, but a high number of cases has been recognized in Europe, India, and the United States. The virus is less transmissible than HIV-1, with sexual contacts being the most frequent route of acquisition. In the absence of specific antiretroviral therapy, most HIV-2 carriers will develop AIDS. Although, it requires more time than HIV-1 infection, CD4+ T cell decline occurs more slowly in HIV-2 than in HIV-1 patients. HIV-2 is resistant to non-nucleoside reverse transcriptase inhibitors (NNRTIs) and some protease inhibitors. Misdiagnosis of HIV-2 in patients mistakenly considered HIV-1-positive or in those with dual infections can cause treatment failures with undetectable HIV-1 RNA. In this era of global integration, clinicians must be aware of when to consider the diagnosis of HIV-2 infection and how to test for this virus. Although there is debate regarding when therapy should be initiated and which regimen should be chosen, recent trials have provided important information on treatment options for HIV-2 infection. In this review, we focus mainly on data available and on the insight they offer about molecular epidemiology, clinical presentation, antiretroviral therapy, and diagnostic tests of HIV-2 infection.

HIV-2 diversity displays two clades within group A with distinct geographical distribution and evolution

Genetic diversity of HIV-2 groups A and B has not yet been fully described, especially in a few Western Africa countries such as Ivory-Coast or Mali. We collected 444 pol, 152 vif, 129 env, and 74 LTR sequences from patients of the French ANRS CO5 HIV-2 cohort completed by 221 pol, 18 vif, 377 env, and 63 LTR unique sequences from public databases. We performed phylogenetic reconstructions and revealed two distinct lineages within HIV-2 group A, herein called A1 and A2, presenting non-negligible genetic distances and distinct geographic distributions as A1 is related to coastal Western African countries and A2 to inland Western countries. Estimated early diversification times for groups A and B in human populations were 1940 [95% higher probability densitiy: 1935–53] and 1961 [1952–70]. A1 experienced an early diversification in 1942 [1937–58] with two distinct early epidemics in Guinea-Bissau or Senegal, raising the possibility of group A emergence in those countries from an initial introduction from Ivory-Coast to Senegal, two former French colonies. Changes in effective population sizes over time revealed that A1 exponentially grew concomitantly to Guinea-Bissau independence war, but both A2 and B lineages experienced a latter growth, starting during the 80s economic crisis. This large HIV-2 genetic analysis provides the existence of two distinct subtypes within group A and new data about HIV-2 early spreading patterns and recent epidemiologic evolution for which data are scarce outside Guinea-Bissau.

Evolution toward beta common chain receptor usage links the matrix proteins of HIV-1 and its ancestors to human erythropoietin

The HIV-1 matrix protein p17 (p17) is a pleiotropic molecule impacting on different cell types. Its interaction with many cellular proteins underlines the importance of the viral protein as a major determinant of human specific adaptation. We previously showed the proangiogenic capability of p17. Here, by integrating functional analysis and receptor binding, we identify a functional epitope that displays molecular mimicry with human erythropoietin (EPO) and promotes angiogenesis through common beta chain receptor (βCR) activation. The functional EPO-like epitope was found to be present in the matrix protein of HIV-1 ancestors SIV originated in chimpanzees (SIVcpz) and gorillas (SIVgor) but not in that of HIV-2 and its ancestor SIVsmm from sooty mangabeys. According to biological data, evolution of the EPO-like epitope showed a clear differentiation between HIV-1/SIVcpz-gor and HIV-2/SIVsmm branches, thus highlighting this epitope on p17 as a divergent signature discriminating HIV-1 and HIV-2 ancestors. P17 is known to enhance HIV-1 replication. Similarly to other βCR ligands, p17 is capable of attracting and activating HIV-1 target cells and promoting a proinflammatory microenvironment. Thus, it is tempting to speculate that acquisition of an epitope on the matrix proteins of HIV-1 ancestors capable of triggering βCR may have represented a critical step to enhance viral aggressiveness and early human-to-human SIVcpz/gor dissemination. The hypothesis that the p17/βCR interaction and βCR abnormal stimulation may also play a role in sustaining chronic activation and inflammation, thus marking the difference between HIV-1 and HIV-2 in term of pathogenicity, needs further investigation.

Human Immunodeficiency Virus-2 (HIV-2): A Summary of the Present Standard of Care and Treatment Options for Individuals Living with HIV-2 in Western Europe

Human immunodeficiency virus-2 (HIV-2) is endemic in some countries in West Africa. Due to the lower prevalence in industrialized countries, there is limited experience and knowledge on the management of individuals living with HIV-2 in Europe. Compared to HIV-1, there are differential characteristics of HIV-2 regarding diagnostic procedures, the clinical course, and, most importantly, antiretroviral therapy. We integrated the published literature on HIV-2 (studies and reports on epidemiology, diagnostics, the clinical course, and treatment), as well as expert experience in diagnosing and clinical care, to provide recommendations for a present standard of medical care of those living with HIV-2 in Western European countries, including an overview of strategies for diagnosis, monitoring, and treatment, with suggestions for effective drug combinations for first- and second-line treatments, post-exposure prophylaxis, and the prevention of mother-to-child transmission, as well as listings of mutations related to HIV-2 drug resistance and C-C motif chemokine receptor type 5 and C-X-C motif chemokine receptor type 4 coreceptor tropism.

HIV-1/2 differentiation in a South African public laboratory

Background

The human immunodeficiency virus type-2 (HIV-2) prevalence in South Africa (SA) is unknown, however, sporadic cases have been reported. Human immunodeficiency virus -1 and 2 differentiation is not part of most South African public laboratories’ testing algorithm. Human immunodeficiency virus -2 diagnosis using serology assays may be complicated by HIV-1 and HIV-2 antibody cross-reactivity.

Objectives

To determine the proportion of HIV-2 infections in specimens that tested HIV-1/2 positive at a public laboratory in Tshwane.

Method

A total of 480 specimens that were previously tested with fourth generation ELISA platforms (Modular E170 [Roche, Switzerland] and Architect i2000 [Abbott, Germany]) were randomly selected. Human immunodeficiency virus -1 and 2 antibody differentiation testing was carried out using the Multispot HIV-1/2 rapid assay (Bio-Rad Laboratories, USA). An in-house nested HIV-2 PCR assay targeting the 5′-long terminal repeats (5′-LTR) region was evaluated and used as a confirmatory test.

Results

The study tested 480 HIV-1/2 seropositive patients and their mean age was 36.7 years (range 3–82 years). Of the 480 patients, 292 (60.8%) were female, 182 (37.9%) were male and 6 (1.3%) were not specified. Human immunodeficiency virus differentiation results were as follows: 466 (97.1%) were positive for only HIV-1 antibodies, 11 (2.3%) [95%CI: (0.98%; 3.74%)] were positive for both HIV-1 and HIV-2 antibodies, 3 (0.6%) were negative for both antibodies and none were positive for only HIV-2 antibodies. Of the 11 specimens with both HIV-1 and HIV-2 antibodies, seven had sufficient volume for confirmatory testing and were all negative on the in-house HIV-2 PCR assay.

Conclusion

The multispot HIV-1/2 rapid assay demonstrated cross-reactivity between HIV-1 and HIV-2 antibodies. Human immunodeficiency virus -2 infections were not detected.

First-line Raltegravir/Emtricitabine/Tenofovir Combination in Human Immunodeficiency Virus Type 2 (HIV-2) Infection: A Phase 2, Noncomparative Trial (ANRS 159 HIV-2)

Background

New options for first-line treatment of human immunodeficiency virus type 2 (HIV-2) infection are needed. We evaluated an integrase inhibitor (raltegravir)–containing regimen.

Methods

Antiretroviral therapy (ART)–naive adults with symptomatic infection by HIV-2 only, CD4 count <500 cells/μL or CD4 decrease >50 cells/μL/year over the past 3 years, or a confirmed plasma HIV-2 RNA (pVL) load ≥100 copies/mL were eligible for this noncomparative trial. The composite primary endpoint was survival at 48 weeks without any of the following: CD4 gain from baseline <100 cells/μL, confirmed pVL ≥40 copies/mL from week 24, raltegravir permanent discontinuation, or incident B or C event. HIV-2 ultrasensitive pVL (uspVL) and total DNA were assessed using in-house polymerase chain reaction (PCR) assays.

Results

Baseline median CD4 count of 30 enrolled individuals (67% women) was 436 cells/µL (interquartile range [IQR], 314–507 cells/µL); pVL was ≥40 copies/mL in 67% of them, uspVL was ≥5 copies/mL in 92%, and total DNA was >6 copies by PCR in 32%. At week 48, the composite endpoint of success was reached in 40% [95% confidence interval, 22.7%–59.4%]. Failure was mainly (50%) due to CD4 gain <100 cells/µL; uspVL was <5 copies/mL in 87% and total DNA >6 copies by PCR in 12% of participants. Median CD4 gain was 87 cells/µL (IQR, 38–213 cells/µL; n = 28). No serious adverse reactions were reported.

Conclusions

Raltegravir-containing ART is a safe option for first-line treatment of HIV-2 infection, yielding a comparable success rate to protease inhibitors.

Clinical Trials Registration

NCT 01605890.

Human Immunodeficiency Virus Type 1 Group O Infection in France: Clinical Features and Immunovirological Response to Antiretrovirals

Background

To obtain reliable clinical data of human immunodeficiency virus type 1 group O (HIV-1/O) infection, and immunovirological responses to combination antiretroviral therapy (cART), in a large series of 101 patients.

Methods

Piecewise linear models were used to estimate CD4 count before and after cART initiation. Kaplan-Meier survival curves were used to estimate time to reach clinical stage C before antiretroviral therapy (ART) and to analyze time to achieve a plasma viral load (pVL) <40 copies/mL following cART initiation. Immunovirological response was assessed at the most recent visit in patients on active follow-up.

Results

Data showed a 16.6% cumulative probability of reaching stage C within 5 years following diagnosis, and a mean CD4 decrease of -30.5 cells/μL/year. cART initiation in ART-naive patients led to a mean CD4 gain of 147 cells/μL after 12 months, and to a median pVL of <40 copies/mL after 3.8 months for 89.3%. Initiation with a nonrecommended nonnucleoside reverse transcriptase inhibitor-based vs a ritonavir-boosted protease inhibitor-based regimen resulted in a much smaller gain of around 100 CD4 cells/μL after 1 year. Patients on follow-up since 2007 had a median CD4 count of 498 cells/μL, and 87% had a pVL <40 copies/mL at the most recent follow-up visit.

Conclusions

This work provides unique data on HIV-1/O infection, in favor of a milder natural evolution than HIV-1 group M (HIV-1/M) and of a highly efficient current management, based on HIV-1/M guidelines, despite genetic divergence. Studies of comparable HIV-1/M and HIV-1/O populations are needed to confirm these results.

HIV-2 as a model to identify a functional HIV cure

Two HIV virus types exist: HIV-1 is pandemic and aggressive, whereas HIV-2 is confined mainly to West Africa and less pathogenic. Despite the fact that it has been almost 40 years since the discovery of AIDS, there is still no cure or vaccine against HIV. Consequently, the concepts of functional vaccines and cures that aim to limit HIV disease progression and spread by persistent control of viral replication without life-long treatment have been suggested as more feasible options to control the HIV pandemic. To identify virus-host mechanisms that could be targeted for functional cure development, researchers have focused on a small fraction of HIV-1 infected individuals that control their infection spontaneously, so-called elite controllers. However, these efforts have not been able to unravel the key mechanisms of the infection control. This is partly due to lack in statistical power since only 0.15% of HIV-1 infected individuals are natural elite controllers. The proportion of long-term viral control is larger in HIV-2 infection compared with HIV-1 infection. We therefore present the idea of using HIV-2 as a model for finding a functional cure against HIV. Understanding the key differences between HIV-1 and HIV-2 infections, and the cross-reactive effects in HIV-1/HIV-2 dual-infection could provide novel insights in developing functional HIV cures and vaccines.

Limited HIV-2 reservoirs in central-memory CD4 T-cells associated to CXCR6 co-receptor expression in attenuated HIV-2 infection

The low pathogenicity and replicative potential of HIV-2 are still poorly understood. We investigated whether HIV-2 reservoirs might follow the peculiar distribution reported in models of attenuated HIV-1/SIV infections, i.e. limited infection of central-memory CD4 T lymphocytes (TCM). Antiretroviral-naive HIV-2 infected individuals from the ANRS-CO5 (12 non-progressors, 2 progressors) were prospectively included. Peripheral blood mononuclear cells (PBMCs) were sorted into monocytes and resting CD4 T-cell subsets (naive [TN], central- [TCM], transitional- [TTM] and effector-memory [TEM]). Reactivation of HIV-2 was tested in 30-day cultures of CD8-depleted PBMCs. HIV-2 DNA was quantified by real-time PCR. Cell surface markers, co-receptors and restriction factors were analyzed by flow-cytometry and multiplex transcriptomic study.

HIV-2 DNA was undetectable in monocytes from all individuals and was quantifiable in TTM from 4 individuals (median: 2.25 log₁₀ copies/10⁶ cells [IQR: 1.99–2.94]) but in TCM from only 1 individual (1.75 log₁₀ copies/10⁶ cells). HIV-2 DNA levels in PBMCs (median: 1.94 log₁₀ copies/10⁶ PBMC [IQR = 1.53–2.13]) positively correlated with those in TTM (r = 0.66, p = 0.01) but not TCM. HIV-2 reactivation was observed in the cells from only 3 individuals. The CCR5 co-receptor was distributed similarly in cell populations from individuals and donors. TCM had a lower expression of CXCR6 transcripts (p = 0.002) than TTM confirmed by FACS analysis, and a higher expression of TRIM5 transcripts (p = 0.004). Thus the low HIV-2 reservoirs differ from HIV-1 reservoirs by the lack of monocytic infection and a limited infection of TCM associated to a lower expression of a potential alternative HIV-2 co-receptor, CXCR6 and a higher expression of a restriction factor, TRIM5. These findings shed new light on the low pathogenicity of HIV-2 infection suggesting mechanisms close to those reported in other models of attenuated HIV/SIV infection models.

HIV-2 induces a still poorly understood attenuated infection compared to HIV-1. We investigated whether this infection might follow peculiarities associated with other models of attenuated HIV-1/SIV infection, i.e. a limited infection of a key subset of memory CD4 T lymphocytes, the central-memory ones (TCM). Thus we studied the infection rates in peripheral blood cells from 14 untreated HIV-2 infected individuals from the ANRS-CO5 HIV-2 cohort, and found; 1) a lack of infection of monocytes, 2) extremely low infection in central-memory CD4+ T lymphocytes while HIV-2 predominated in the transitional-memory cells, 3) a poor replicative capacity of HIV-2 in individuals cells. We then investigated the cellular expression of a hundred-host genes potentially involved in HIV-2 control. We found in individuals’ TCM cells, compared to TTM ones, a lower expression of CXCR6, a potentially alternative co-receptor of HIV-2 but not of HIV-1, and a higher expression of TRIM5α, a restriction factor to which HIV-2 is more sensitive than HIV-1. Altogether our findings shed new light on the low pathogenicity of HIV-2 suggesting mechanisms close to those reported in other models of attenuated HIV/SIV infection models.

Long-term follow-up of HIV-2-related AIDS and mortality in Guinea-Bissau: a prospective open cohort study

BACKGROUND

HIV type 2 (HIV-2) is considered more benign and has fewer pathogenic consequences than HIV type 1 (HIV-1) for most infected individuals. However, reliable estimates of time to AIDS and mortality among those with HIV-2 infection are absent. We therefore aimed to compare the time to AIDS and mortality, and the CD4 T-cell dynamics between those infected with HIV-1 and HIV-2.

METHODS

We did a prospective open cohort study. We included all police officers with regular employment from police stations in both urban and rural areas of Guinea-Bissau since Feb 6, 1990. We continued to include participants until Sept 28, 2009, and follow-up of HIV-1-positive and HIV-2-positive individuals continued until Sept 28, 2013. We collected blood samples at enrolment and at scheduled annual follow-up visits at police stations. We analysed longitudinal data from individuals infected with HIV-1 and HIV-2 according to time to AIDS, time to death, and T-cell dynamics. Time of HIV infection was estimated as the mid-timepoint between last HIV-seronegative and first HIV-seropositive sample. Data from an additional 2984 HIV-uninfected individuals from the same population were analysed to assess the effect of natural mortality on HIV-related mortality.

FINDINGS

872 participants tested HIV positive during the 23-year study period: 408 were infected with HIV-1 (183 infected before and 225 infected after enrolment) and 464 were infected with HIV-2 (377 before and 87 after enrolment). The median time from HIV infection to development of AIDS was 6·2 years (95% CI 5·4-7·1) for HIV-1 infection and 14·3 years (10·7-18·0) for HIV-2 infection (p<0·0001). The median survival time after HIV infection was 8·2 years (95% CI 7·5-8·9) for HIV-1 infection and 15·6 years (12·0-19·2) for HIV-2 infection (p<0·0001). Individuals who were infected with HIV-1 or HIV-2 before enrolment showed similar results. Comparison with uninfected individuals indicated limited confounding contribution from natural mortality. Mean CD4 percentages were higher in individuals with HIV-2 than in those with HIV-1 during early infection (28·0% [SE 1·3] vs 22·3% [1·7]; p=0·00094) and declined at a slower rate (0·4% [0·2] vs 0·9% [0·2] per year; p=0·028). HIV-2-infected individuals developed clinical AIDS at higher mean CD4 percentages (18·2%, IQR 7·2-25·4) than HIV-1-infected individuals (8·2%, 3·0-13·8; p<0·0001).

INTERPRETATION

Our results show that both HIV-1-infected and HIV-2-infected individuals have a high probability of developing and dying from AIDS without antiretroviral treatment.

FUNDING

Swedish International Development Agency, Swedish Research Council, Swedish Society of Medical Research, Medical Faculty at Lund University, and Region Skåne Research and Development.

CD4 cell count response to first-line combination ART in HIV-2+ patients compared with HIV-1+ patients: a multinational, multicohort European study

Background

CD4 cell recovery following first-line combination ART (cART) is poorer in HIV-2+ than in HIV-1+ patients. Only large comparisons may allow adjustments for demographic and pretreatment plasma viral load (pVL).

Methods

ART-naive HIV+ adults from two European multicohort collaborations, COHERE (HIV-1 alone) and ACHIeV2e (HIV-2 alone), were included, if they started first-line cART (without NNRTIs or fusion inhibitors) between 1997 and 2011. Patients without at least one CD4 cell count before start of cART, without a pretreatment pVL and with missing a priori-defined covariables were excluded. Evolution of CD4 cell count was studied using adjusted linear mixed models.

Results

We included 185 HIV-2+ and 30321 HIV-1+ patients with median age of 46 years (IQR 36-52) and 37 years (IQR 31-44), respectively. Median observed pretreatment CD4 cell counts/mm3 were 203 (95% CI 100-290) in HIV-2+ patients and 223 (95% CI 100-353) in HIV-1+ patients. Mean observed CD4 cell count changes from start of cART to 12 months were +105 (95% CI 77-134) in HIV-2+ patients and +202 (95% CI 199-205) in HIV-1+ patients, an observed difference of 97 cells/mm3 in 1 year. In adjusted analysis, the mean CD4 cell increase was overall 25 CD4 cells/mm3/year lower (95% CI 5-44; P = 0.0127) in HIV-2+ patients compared with HIV-1+ patients.

Conclusions

A poorer CD4 cell increase during first-line cART was observed in HIV-2+ patients, even after adjusting for pretreatment pVL and other potential confounders. Our results underline the need to identify more potent therapeutic regimens or strategies against HIV-2.

HIV-2 infection is associated with preserved GALT homeostasis and epithelial integrity despite ongoing mucosal viral replication

The mechanisms that enable preservation of gut mucosal integrity during persistent viral replication and inherent inflammation remain unclear. Here, we investigated, for the first time, gut homeostasis in HIV-2 infection, a naturally occurring form of attenuated HIV disease. We found viral replication in both sigmoid and ileum of asymptomatic HIV-2+ patients (range: 240-851 circulating CD4+T-cells per μl) despite their undetectable viremia, accompanied by interferon-γ-producing CD8 T-cell expansion, irrespective of antiretroviral treatment. Nevertheless, there was no CD4 T-cell depletion, and Foxp3+ and IL-17- or IL-22-producing CD4 T-cell numbers were unaffected. Moreover, IL-22-producing innate lymphoid cells and IL-22-induced antimicrobial peptides and mucins were maintained. In agreement, the epithelium histology was preserved, including tight junction protein zonula occludens (ZO-1) levels. Furthermore, in vitro infection of colon epithelia with primary isolates revealed no HIV-2 impact on ZO-1 expression. Notably, sigmoid transcriptional levels of CCL20 and CCL28 were significantly increased, in direct correlation with GM-CSF, indicating a local response able to enhance CD4 T-cell recruitment. In conclusion, maintenance of mucosal integrity in HIV-2 infection was associated with T-cell recruitment responses, potentially counteracting CD4 T-cell depletion due to HIV-2 replication. These data have unique implications for the design of therapies targeting gut homeostasis in HIV-1 infection and other chronic inflammatory settings.

Potency of HIV-2-specific antibodies increase in direct association with loss of memory B cells

: Potent HIV-neutralizing antibodies are critical for vaccination and viral reservoir control. High levels of neutralizing antibodies characterize HIV-2 infection, a naturally occurring model of attenuated HIV disease with low-to-undectable viremia. We found that HIV-2-specific antibody potency increased in direct association with the loss of both switched and unswitched memory B cells in untreated HIV-2 infection. Thus, HIV antibody affinity maturation is linked to memory B-cell exhaustion even in reduced viremia settings.

Insight into HIV-2 latency may disclose strategies for a cure for HIV-1 infection

HIV-1 and HIV-2 originate from two distinct zoonotic transmissions of simian immunodeficiency viruses from primate to human. Although both share similar modes of transmission and can result in the development of AIDS with similar clinical manifestations, HIV-2 infection is generally milder and less likely to progress to AIDS. HIV is currently incurable due to the presence of HIV provirus integrated into the host DNA of long-lived memory cells of the immune system without active replication. As such, the latent virus is immunologically inert and remains insensitive to the administered antiviral drugs targeting active viral replication steps. Recent evidence suggests that persistent HIV replication may occur in anatomical sanctuaries such as the lymphoid tissue due to low drug penetration. At present, different strategies are being evaluated either to completely eradicate the virus from the patient (sterilising cure) or to allow treatment interruption without viral rebound (functional cure). Because HIV-2 is naturally less pathogenic and displays a more latent phenotype than HIV-1, it may represent a valuable model that provides elementary information to cure HIV-1 infection. Insight into the viral and cellular determinants of HIV-2 replication may therefore pave the way for alternative strategies to eradicate HIV-1 or promote viral remission.

Effect of sex and age on outcomes among HIV-2-infected patients starting antiretroviral therapy in West Africa

OBJECTIVES

HIV-2-infected individuals usually initiate antiretroviral therapy (ART) at an advanced age compared with HIV-1 patients, with a potential impact on treatment outcomes. This study aimed to investigate the effect of sex and age on mortality and loss to follow-up (LTFU) among HIV-2-infected individuals initiating ART.

METHODS

Analyses were conducted using the database of the International Epidemiological Databases to Evaluate AIDS's collaboration in West Africa. LTFU was considered if the interval between the last visit and the closing date for this analysis was more than 180 days. Probability of death and LTFU were estimated with Kaplan-Meier methods. A Cox regression model was used to identify factors associated with death and LTFU over the first 24 months on ART.

RESULTS

A total of 1825 HIV-2-infected individuals, including 60% women were considered for this analysis. The median age, baseline CD4 cell count, and follow-up duration were 45 years [interquartile range (IQR; 38-52)], 185 cells/μl [IQR (95-297)], and 28.8 months [IQR (9.8-58.9)], respectively. Over the first 24 months, the mortality rate was 5.2/100 person-years of observation [95% confidence interval (CI; 4.4-6.1)] and 469 (25.7%) were LTFU. Male sex [hazard ratio (HR) = 1.9; 95% CI (1.4; 2.8)], baseline CD4 cell count less than 100 cell/μl [HR = 4.4 95% CI (1.7; 11.1); ref at least 350 cell/μl], haemoglobin 7.5-10 g/dl [HR = 2.4 95% CI (1.3; 4.4); ref at least 12 g/dl], and BMI less than 18 kg/m [HR = 2.1 95% CI (1.3; 3.4); ref = 18-25 kg/m] were associated with higher mortality over the first 24 months. Similar associations were found for LTFU.

CONCLUSION

Mortality and LTFU are high among ART-receiving HIV-2-infected individuals and higher in men than in women. There is a critical need to further determine the causes of poor retention and implement sex-specific solutions that improve outcomes in HIV-2 ART programmes.

Mortality and survival patterns of people living with HIV-2

PURPOSE OF REVIEW

People living with HIV-2 infected usually initiate antiretroviral therapy (ART) at an advanced period in the course of their infection after a long asymptomatic period characterized by high CD4 cell count and thus at a relatively advanced age. In the new international context of early and universal ART initiation, the aim was to review survival patterns among HIV-2 infected patients, either on ART or not.

RECENT FINDINGS

Very few reports were published on mortality in people living with HIV-2 during the last 5 years. People living with HIV-2 experience high mortality rates although lower than people living with HIV-1 before ART initiation. They seem to survive longer regardless of the conditions of ART use. Mortality is associated with late presentation, male sex, CD4 cell count less than 500 cell/μl, high plasma viral load, hemoglobin rate less than 8 g/dl and body mass index less than 18 kg/m.

SUMMARY

People living with HIV-2 initiate ART later than HIV-1 and HIV duals, resulting in higher disease progression and mortality rate. The clinical management of HIV-2 infected patients should now include early diagnosis and treatment initiation as per international guidelines. Further research needs to explore the 'what to start' question and document specific causes of death in people living with HIV-2 and enrolled in care in Africa.

Preservation of Lymphopoietic Potential and Virus Suppressive Capacity by CD8+ T Cells in HIV-2-Infected Controllers

Compared with HIV-1, HIV-2 infection is characterized by a larger proportion of slow or nonprogressors. A better understanding of HIV-2 pathogenesis should open new therapeutic avenues to establish control of HIV-1 replication in infected patients. In this study, we studied the production of CD8(+) T cells and their capacity for viral control in HIV-2 controllers from the French ANRS CO5 HIV-2 cohort. HIV-2 controllers display a robust capacity to support long-term renewal of the CD8(+) T cell compartment by preserving immune resources, including hematopoietic progenitors and thymic activity, which could contribute to the long-term maintenance of the CD8(+) T cell response and the avoidance of premature immune aging. Our data support the presence of HIV-2 Gag-specific CD8(+) T cells that display an early memory differentiation phenotype and robust effector potential in HIV-2 controllers. Accordingly, to our knowledge, we show for the first time that HIV-2 controllers possess CD8(+) T cells that show an unusually strong capacity to suppress HIV-2 infection in autologous CD4(+) T cells ex vivo, an ability that likely depends on the preservation of host immune resources. This effective and durable antiviral response probably participates in a virtuous circle, during which controlled viral replication permits the preservation of potent immune functions, thus preventing HIV-2 disease progression.

Immunologic response in treatment-naïve HIV-2-infected patients: the IeDEA West Africa cohort

INTRODUCTION

Response to antiretroviral therapy (ART) among individuals infected with HIV-2 is poorly described. We compared the immunological response among patients treated with three nucleoside reverse-transcriptase inhibitors (NRTIs) to boosted protease inhibitor (PI) and unboosted PI-based regimens in West Africa.

METHODS

This prospective cohort study enrolled treatment-naïve HIV-2-infected patients within the International Epidemiological Databases to Evaluate AIDS collaboration in West Africa. We used mixed models to compare the CD4 count response to treatment over 12 months between regimens.

RESULTS

Of 422 HIV-2-infected patients, 285 (67.5%) were treated with a boosted PI-based regimen, 104 (24.6%) with an unboosted PI-based regimen and 33 (7.8%) with three NRTIs. Treatment groups were comparable with regard to gender (54.5% female) and median age at ART initiation (45.3 years; interquartile range 38.3 to 51.8). Treatment groups differed by clinical stage (21.2%, 16.8% and 17.3% at CDC Stage C or World Health Organization Stage IV for the triple NRTI, boosted PI and unboosted PI groups, respectively, p=0.02), median length of follow-up (12.9, 17.7 and 44.0 months for the triple NRTI, the boosted PI and the unboosted PI groups, respectively, p<0.001) and baseline median CD4 count (192, 173 and 129 cells/µl in the triple NRTI, the boosted PI and the unboosted PI-based regimen groups, respectively, p=0.003). CD4 count recovery at 12 months was higher for patients treated with boosted PI-based regimens than those treated with three NRTIs or with unboosted PI-based regimens (191 cells/µl, 95% CI 142 to 241; 110 cells/µl, 95% CI 29 to 192; 133 cells/µl, 95% CI 80 to 186, respectively, p=0.004).

CONCLUSIONS

In this observational study using African data, boosted PI-containing regimens had better immunological response compared to triple NRTI combinations and unboosted PI-based regimens at 12 months. A randomized clinical trial is still required to determine the best initial regimen for treating HIV-2 infected patients.

Tropism distribution among antiretroviral-naive HIV-2-infected patients

The aim of this study was to describe HIV-2 R5/X4-tropism distribution in antiretroviral-naive HIV-2-infected patients. Population sequencing of the gp105 region was performed on peripheral blood mononuclear cells issued from 151 antiretroviral-naive patients. Tropism was successfully determined in 46 of 151 samples (30%) with six of 46 (13%) X4-tropic viruses. X4-tropism was associated with lower CD4 cell count (337 vs. 551/mm; P = 0.032) but not with plasma viral load. Thus, X4-tropism prevalence in HIV-2 antiretroviral-naive patients is similar to that observed in HIV-1.

Inferring HIV incidence from case surveillance with CD4+ cell counts

BACKGROUND

In some countries, HIV surveillance is based on case-reporting of newly diagnosed infections. We present a new back-projection method for estimating HIV-incidence trends using individuals' CD4 cell counts at diagnosis.

METHODS

On the basis of a review of CD4 cell count distributions among HIV-uninfected people, CD4 cell count following primary infection, and rates of CD4 cell count decline over time among people with HIV, we simulate the expected distribution in time between infection and diagnosis. Applying this to all diagnosed individuals provides a distribution of likely infection times and estimates for population incidence, level of undiagnosed HIV, and the average time from infection to diagnosis each year. We applied this method to the national HIV case surveillance data of Australia for 1983-2013.

RESULTS

The estimated number of new HIV infections in Australia in 2013 was 912 (95% uncertainty bound 835-1002). We estimate that 2280 (95% uncertainty bound 1900-2830) people were living with undiagnosed HIV at the end of 2013, corresponding to approximately 9.4% (95% uncertainty bound 7.8-10.1%) of all people living with HIV. With increases in the average CD4 count at diagnosis, the inferred HIV testing rate has been increasing over time and the estimated mean and median times between infection and diagnosis have decreased substantially. However, the estimated mean time between infection and diagnosis is considerably greater than the median, indicating that some people remain undiagnosed for long periods. Differences were found between cases attributable to male homosexual exposure versus other cases.

CONCLUSION

This methodology provides a novel way of estimating population incidence by combining diagnosis dates and CD4 cell counts at diagnosis.

Plasma HIV-2 RNA According to CD4 Count Strata among HIV-2-Infected Adults in the IeDEA West Africa Collaboration

Background

Plasma HIV-1 RNA monitoring is one of the standard tests for the management of HIV-1 infection. While HIV-1 RNA can be quantified using several commercial tests, no test has been commercialized for HIV-2 RNA quantification. We studied the relationship between plasma HIV-2 viral load (VL) and CD4 count in West African patients who were either receiving antiretroviral therapy (ART) or treatment-naïve.

Method

A cross sectional survey was conducted among HIV-2-infected individuals followed in three countries in West Africa from March to December 2012. All HIV-2 infected-patients who attended one of the participating clinics were proposed a plasma HIV-2 viral load measurement. HIV-2 RNA was quantified using the new ultrasensitive in-house real-time PCR assay with a detection threshold of 10 copies/ mL (cps/mL).

Results

A total of 351 HIV-2-infected individuals participated in this study, of whom 131 (37.3%) were treatment naïve and 220 (62.7%) had initiated ART. Among treatment-naïve patients, 60 (46.5%) had undetectable plasma HIV-2 viral load (<10 cps/mL), it was detectable between 10-100 cps/mL in 35.8%, between 100-1000 cps/mL in 11.7% and >1000 cps/mL in 6.0% of the patients. Most of the treatment-naïve patients (70.2%) had CD4-T cell count ≥500 cells/mm³ and 43 (46.7%) of these patients had a detectable VL (≥10 cps/mL). Among the 220 patients receiving ART, the median CD4-T cell count rose from 231 to 393 cells/mm³ (IQR [259-561]) after a median follow-up duration of 38 months and 145 (66.0%) patients had CD4-T cell count ≤ 500 cells/mm³ with a median viral load of 10 cps/mL (IQR [10-33]). Seventy five (34.0%) patients had CD4-T cell count ≥ 500 cells/mm³, among them 14 (18.7%) had a VL between 10-100 cps/mL and 2 (2.6%) had VL >100 cps/mL.

Conclusion

This study suggests that the combination of CD4-T cell count and ultrasensitive HIV-2 viral load quantification with a threshold of 10 cps/mL, could improve ART initiation among treatment naïve HIV-2-infected patients and the monitoring of ART response among patients receiving treatment.

Antiretroviral therapy response among HIV-2 infected patients: a systematic review

BACKGROUND

Few data are available on antiretroviral therapy (ART) response among HIV-2 infected patients. We conducted a systematic review on treatment outcomes among HIV-2 infected patients on ART, focusing on the immunological and virological responses in adults.

METHODS

Data were extracted from articles that were selected after screening of PubMed/MEDLINE up to November 2012 and abstracts of the 1996-2012 international conferences. Observational cohorts, clinical trials and program reports were eligible as long as they reported data on ART response (clinical, immunological or virological) among HIV-2 infected patients. The determinants investigated included patients' demographic characteristics, CD4 cell count at baseline and ART received.

RESULTS

Seventeen reports (involving 976 HIV-2 only and 454 HIV1&2 dually reactive patients) were included in the final review, and the analysis presented in this report are related to HIV-2 infected patients only. There was no randomized controlled trial and only two cohorts had enrolled more than 100 HIV-2 only infected patients. The median CD4 count at ART initiation was 165 cells/mm3, [IQR; 137-201] and the median age at ART initiation was 44 years (IQR: 42-48 years). Ten studies included 103 patients treated with three nucleoside reverse transcriptase inhibitors (NRTI). Protease inhibitor (PI) based regimens were reported by 16 studies. Before 2009, the most frequent PIs used were Nelfinavir and Indinavir, whereas it was Lopinavir/ritonavir thereafter. The immunological response at month-12 was reported in six studies and the mean CD4 cell count increase was +118 cells/μL (min-max: 45-200 cells/μL).

CONCLUSION

Overall, clinical and immuno-virologic outcomes in HIV-2 infected individuals treated with ART are suboptimal. There is a need of randomized controlled trials to improve the management and outcomes of people living with HIV-2 infection.

Antiretroviral therapy and drug resistance in human immunodeficiency virus type 2 infection

One to two million people worldwide are infected with the human immunodeficiency virus type 2 (HIV-2), with highest prevalences in West African countries, but also present in Western Europe, Asia and North America. Compared to HIV-1, HIV-2 infection undergoes a longer asymptomatic phase and progresses to AIDS more slowly. In addition, HIV-2 shows lower transmission rates, probably due to its lower viremia in infected individuals. There is limited experience in the treatment of HIV-2 infection and several antiretroviral drugs used to fight HIV-1 are not effective against HIV-2. Effective drugs against HIV-2 include nucleoside analogue reverse transcriptase (RT) inhibitors (e.g. zidovudine, tenofovir, lamivudine, emtricitabine, abacavir, stavudine and didanosine), protease inhibitors (saquinavir, lopinavir and darunavir), and integrase inhibitors (raltegravir, elvitegravir and dolutegravir). Maraviroc, a CCR5 antagonist blocking coreceptor binding during HIV entry, is active in vitro against CCR5-tropic HIV-2 but more studies are needed to validate its use in therapeutic treatments against HIV-2 infection. HIV-2 strains are naturally resistant to a few antiretroviral drugs developed to suppress HIV-1 propagation such as nonnucleoside RT inhibitors, several protease inhibitors and the fusion inhibitor enfuvirtide. Resistance selection in HIV-2 appears to be faster than in HIV-1. In this scenario, the development of novel drugs specific for HIV-2 is an important priority. In this review, we discuss current anti-HIV-2 therapies and mutational pathways leading to drug resistance.

Evolution of the human immunodeficiency virus type 2 envelope in the first years of infection is associated with the dynamics of the neutralizing antibody response

BACKGROUND

Differently from HIV-1, HIV-2 disease progression usually takes decades without antiretroviral therapy and the majority of HIV-2 infected individuals survive as elite controllers with normal CD4⁺ T cell counts and low or undetectable plasma viral load. Neutralizing antibodies (Nabs) are thought to play a central role in HIV-2 evolution and pathogenesis. However, the dynamic of the Nab response and resulting HIV-2 escape during acute infection and their impact in HIV-2 evolution and disease progression remain largely unknown. Our objective was to characterize the Nab response and the molecular and phenotypic evolution of HIV-2 in association with Nab escape in the first years of infection in two children infected at birth.

RESULTS

CD4⁺ T cells decreased from about 50% to below 30% in both children in the first five years of infection and the infecting R5 viruses were replaced by X4 viruses within the same period. With antiretroviral therapy, viral load in child 1 decreased to undetectable levels and CD4+ T cells recovered to normal levels, which have been sustained at least until the age of 12. In contrast, viral load increased in child 2 and she progressed to AIDS and death at age 9. Beginning in the first year of life, child 1 raised high titers of antibodies that neutralized primary R5 isolates more effectively than X4 isolates, both autologous and heterologous. Child 2 raised a weak X4-specific Nab response that decreased sharply as disease progressed. Rate of evolution, nucleotide and amino acid diversity, and positive selection, were significantly higher in the envelope of child 1 compared to child 2. Rates of R5-to-X4 tropism switch, of V1 and V3 sequence diversification, and of convergence of V3 to a β-hairpin structure were related with rate of escape from the neutralizing antibodies.

CONCLUSION

Our data suggests that the molecular and phenotypic evolution of the human immunodeficiency virus type 2 envelope are related with the dynamics of the neutralizing antibody response providing further support for a model in which Nabs play an important role in HIV-2 pathogenesis.

The role of neutralizing antibodies in prevention of HIV-1 infection: what can we learn from the mother-to-child transmission context?

In most viral infections, protection through existing vaccines is linked to the presence of vaccine-induced neutralizing antibodies (NAbs). However, more than 30 years after the identification of AIDS, the design of an immunogen able to induce antibodies that would neutralize the highly diverse HIV-1 variants remains one of the most puzzling challenges of the human microbiology. The role of antibodies in protection against HIV-1 can be studied in a natural situation that is the mother-to-child transmission (MTCT) context. Indeed, at least at the end of pregnancy, maternal antibodies of the IgG class are passively transferred to the fetus protecting the neonate from new infections during the first weeks or months of life. During the last few years, strong data, presented in this review, have suggested that some NAbs might confer protection toward neonatal HIV-1 infection. In cases of transmission, it has been shown that the viral population that is transmitted from the mother to the infant is usually homogeneous, genetically restricted and resistant to the maternal HIV-1-specific antibodies. Although the breath of neutralization was not associated with protection, it has not been excluded that NAbs toward specific HIV-1 strains might be associated with a lower rate of MTCT. A better identification of the antibody specificities that could mediate protection toward MTCT of HIV-1 would provide important insights into the antibody responses that would be useful for vaccine development. The most convincing data suggesting that NAbs migh confer protection against HIV-1 infection have been obtained by experiments of passive immunization of newborn macaques with the first generation of human monoclonal broadly neutralizing antibodies (HuMoNAbs). However, these studies, which included only a few selected subtype B challenge viruses, provide data limited to protection against a very restricted number of isolates and therefore have limitations in addressing the hypervariability of HIV-1. The recent identification of highly potent second-generation cross-clade HuMoNAbs provides a new opportunity to evaluate the efficacy of passive immunization to prevent MTCT of HIV-1.

Natural history of HIV-control since seroconversion

OBJECTIVES

HIV-controllers spontaneously maintain HIV viremia at an undetectable level. We aimed to describe the delay to control from seroconversion, the duration of control, and risk factors for losing control.

METHODS

HIV-controllers were identified from a pooled dataset of 24 seroconverter cohorts from Europe, Australia, and Canada (CASCADE). HIV-controllers had at least five consecutive viral loads less than 400/500 copies/ml, while antiretroviral therapy naive, for at least 5 years after seroconversion. End of control was defined as two consecutive viral loads above 2000 copies/ml. Duration of control was described using Kaplan-Meier estimates; factors associated with duration of control were identified using a Cox model. CD4⁺ cell count evolution during control was described using a mixed model.

RESULTS

Of 9896 eligible seroconverters, we identified 140 (1.4%) HIV-controllers, the largest database of HIV-controllers followed from seroconversion. For 64 with viral load measured within 24 months from seroconversion, median delay to control was 16.7 (interquartile range: 7.8-37.9) months. Probability of maintaining control 20 years after seroconversion was 0.74 [95% confidence interval (CI): 0.64-0.85]. Occurrence of blips followed by return to undetectability did not increase the risk of loss of control [hazard ratio: 0.81 (95% CI: 0.10-6.70)]. However, CD4⁺ cell loss during control was significantly accelerated in individuals with blips.

CONCLUSION

In most individuals, control occurred rapidly after seroconversion; however, more than 3 years were required to achieve control in 25% of HIV-controllers. Control may be sustained even when CD4⁺ cell levels are below 500 cells/μl, opening important new perspectives to understand the physiopathology underlying control.

Highly sensitive plasma RNA quantification by real-time PCR in HIV-2 group A and group B infection

Plasma HIV-2 viral load has been reported as predictive of AIDS in HIV-2 infected patient but the lack of sensitivity of the current HIV2 viral load assay is a limitation for the monitoring of the HIV-2-infected patients.

OBJECTIVE

To validate a new quantification assay based on a synthetic HIV-2 RNA transcript and real-time PCR with primers and probes selected in the LTR region, together with high-performance reagents and a protective RNA carrier.

STUDY DESIGN

We quantified 23 HIV-2 group A and B supernatants and 58 plasma samples with our TAQMAN-PCR assay and compared the results to those of our previously published in a real time reference PCR performed onto Light Cycler technology, the LC-PCR with a detection of 2.0 log10 copies/ml.

RESULTS

The performance of TAQMAN-PCR was significantly improved, yielding a detection limit of 17 RNA copies/ml. There was a major difference (1-5 log10 copies/ml) between LC-PCR and TAQMAN-PCR values for HIV-2 group B supernatants. Twenty-six of 27 plasma samples with levels higher than 2.0 log10 copies/ml in LC-PCR were positive by TAQMAN-PCR. Ten of the 31 plasma samples below the LC-PCR detection limit were quantifiable with the TAQMAN-PCR.

CONCLUSIONS

The new primers and probe in the LTR region can circumvent HIV-2 diversity, making our method suitable for use in HIV-2 group B-infected patients. Use of a high-performance RT enzyme and RNA carrier protection contributed to improving the detection limit. This study confirms that plasma viral load is lower than 17 copies/ml in a large number of HIV-2-infected patients.

Characteristics of HIV-2 and HIV-1/HIV-2 Dually Seropositive Adults in West Africa Presenting for Care and Antiretroviral Therapy: The IeDEA-West Africa HIV-2 Cohort Study

Background

HIV-2 is endemic in West Africa. There is a lack of evidence-based guidelines on the diagnosis, management and antiretroviral therapy (ART) for HIV-2 or HIV-1/HIV-2 dual infections. Because of these issues, we designed a West African collaborative cohort for HIV-2 infection within the framework of the International epidemiological Databases to Evaluate AIDS (IeDEA).

Methods

We collected data on all HIV-2 and HIV-1/HIV-2 dually seropositive patients (both ARV-naive and starting ART) and followed-up in clinical centres in the IeDEA-WA network including a total of 13 clinics in five countries: Benin, Burkina-Faso Côte d’Ivoire, Mali, and Senegal, in the West Africa region.

Results

Data was merged for 1,754 patients (56% female), including 1,021 HIV-2 infected patients (551 on ART) and 733 dually seropositive for both HIV-1 and HIV 2 (463 on ART). At ART initiation, the median age of HIV-2 patients was 45.3 years, IQR: (38.3–51.7) and 42.4 years, IQR (37.0–47.3) for dually seropositive patients (p = 0.048). Overall, 16.7% of HIV-2 patients on ART had an advanced clinical stage (WHO IV or CDC-C). The median CD4 count at the ART initiation is 166 cells/mm³, IQR (83–247) among HIV-2 infected patients and 146 cells/mm³, IQR (55–249) among dually seropositive patients. Overall, in ART-treated patients, the CD4 count increased 126 cells/mm³ after 24 months on ART for HIV-2 patients and 169 cells/mm³ for dually seropositive patients. Of 551 HIV-2 patients on ART, 5.8% died and 10.2% were lost to follow-up during the median time on ART of 2.4 years, IQR (0.7–4.3).

Conclusions

This large multi-country study of HIV-2 and HIV-1/HIV-2 dual infection in West Africa suggests that routine clinical care is less than optimal and that management and treatment of HIV-2 could be further informed by ongoing studies and randomized clinical trials in this population.

Preserved CD4 T-cell telomere length during long-lasting HIV-2 infection

HIV-2 infection features a much slower course than HIV-1 infection, often asymptomatic for over 20 years, without antiretroviral therapy (ART). Nevertheless, CD4 T cells progressively decline, in direct correlation with immune activation and cell cycling. We report, for the first time, preserved telomere length within naive and memory CD4 subsets in prolonged HIV-2 infection despite the increased CD4 turnover.

Resistance to antibody neutralization in HIV-2 infection occurs in late stage disease and is associated with X4 tropism

OBJECTIVES

To characterize the nature and dynamics of the neutralizing antibody (NAb) response and escape in chronically HIV-2 infected patients.

METHODS

Twenty-eight chronically infected adults were studied over a period of 1-4 years. The neutralizing activity of plasma immunoglobulin G (IgG) antibodies against autologous and heterologous primary isolates was analyzed using a standard assay in TZM-bl cells. Coreceptor usage was determined in ghost cells. The sequence and predicted three-dimensional structure of the C2V3C3 Env region were determined for all isolates.

RESULTS

Only 50% of the patients consistently produced IgG NAbs to autologous and contemporaneous virus isolates. In contrast, 96% of the patients produced IgG antibodies that neutralized at least two isolates of a panel of six heterologous R5 isolates. Breadth and potency of the neutralizing antibodies were positively associated with the number of CD4(+) T cells and with the titer and avidity of C2V3C3-specific binding IgG antibodies. X4 isolates were obtained only from late stage disease patients and were fully resistant to neutralization. The V3 loop of X4 viruses was longer, had a higher net charge, and differed markedly in secondary structure compared to R5 viruses.

CONCLUSION

Most HIV-2 patients infected with R5 isolates produce C2V3C3-specific neutralizing antibodies whose potency and breadth decreases as the disease progresses. Resistance to antibody neutralization occurs in late stage disease and is usually associated with X4 viral tropism and major changes in V3 sequence and conformation. Our studies support a model of HIV-2 pathogenesis in which the neutralizing antibodies play a central role and have clear implications for the vaccine field.

Memory B-cell depletion is a feature of HIV-2 infection even in the absence of detectable viremia

OBJECTIVE

Memory B-cell loss has long been recognized as an important contributor to HIV immunodeficiency. HIV-2 infection, which is characterized by a slow rate of progression to AIDS and reduced to undetectable viremia, provides a unique model to investigate B-cell disturbances.

DESIGN AND METHODS

B-cell subsets were evaluated in 38 HIV-2-infected individuals, along with markers of T-cell activation and serum levels of immunoglobulins and a major B-cell homeostatic cytokine, B-cell activating factor (BAFF). Untreated HIV-1-infected and seronegative control individuals were studied in parallel. Statistical analysis was performed using Mann-Whitney tests and Spearman's correlations.

RESULTS

We found that HIV-2 was associated with significant depletion of both unswitched (CD27(+)IgD(+)) and switched (CD27(+)IgD(neg)) memory B-cells that directly correlated with T-cell activation, even in individuals with undetectable plasma viral load. Nevertheless, the presence of detectable viremia, even at low levels, was associated with significant memory B-cell loss and higher BAFF levels. Moreover, these alterations were not recovered by antiretroviral-therapy, as treated HIV-2-infected patients showed more pronounced B-cell disturbances, possibly related to their extended length of infection.

CONCLUSION

These first data regarding B-cell imbalances during HIV-2 infection show that, irrespective of viremia, prolonged HIV infection leads to irreversible damage of memory B-cell homeostasis.

PD-1 and its ligand PD-L1 are progressively up-regulated on CD4 and CD8 T-cells in HIV-2 infection irrespective of the presence of viremia

OBJECTIVE

Hyper-immune activation is a main determinant of HIV disease progression, potentially counter-acted by T-cell inhibitory pathways. Here we investigated, for the first time, inhibitory molecules in HIV-2 infection, a naturally occurring attenuated form of HIV disease, associated with reduced viremia and very slow rates of CD4 T-cell decline.

DESIGN

Programmed death (PD)-1/PD-L1, an important pathway in limiting immunopathology, and its possible relationship with T-cell immunoglobulin and mucin-domain containing molecule-3 (TIM-3), a recently identified inhibitory molecule, were studied in untreated HIV-2 and HIV-1 cohorts, matched for degree of CD4 T-cell depletion, and noninfected individuals.

METHODS

Flow cytometric analysis of T-cell expression of PD-1, PD-L1 and TIM-3, combined with markers of cell differentiation, activation, cycling and survival. Statistical analysis was performed using ANOVA, Mann-Whitney/Wilcoxon tests, Spearman's correlations, multiple linear regressions and canonical correlation analysis.

RESULTS

T-cell expression of PD-1 and PD-L1 was tightly associated and directly correlated with CD4 T-cell depletion and immune activation in HIV-2 infection. No such correlation was found for PD-L1 expression in HIV-1-positive patients. Central memory and intermediate memory cells, rather than terminally differentiated T-cells, expressed the highest levels of both PD-1 and PD-L1 molecules. Conversely, TIM-3 expression was independent of T-cell differentiation and dissociated from cell cycling, suggesting distinct induction mechanisms. Importantly, in contrast with HIV-1, no significant increases in TIM-3 expression were found in the HIV-2 cohort.

CONCLUSIONS

Our data suggest that PD-1/PD-L1 molecules, rather than markers of T-cell exhaustion, may act as modulators of T-cell immune activation, contributing to the slower course of HIV-2 infection. These data have implications for the design of antiretroviral therapy-complementary immune-based strategies.

Mortality and immunovirological outcomes on antiretroviral therapy in HIV-1 and HIV-2-infected individuals in the Gambia

OBJECTIVES

This study's objective was to assess outcomes in HIV-1 and HIV-2 infected antiretroviral therapy (ART)-naïve patients starting ART in the Gambia, West Africa.

DESIGN

A cohort design was used to estimate survival in ART patients and determine whether survival and time to virologic failure varied across patient subgroups.

METHODS

Mortality, virologic failures and CD4(+) cell recovery were assessed in a clinical cohort of patients from the Genito-Urinary Medicine (GUM) clinic of the MRC Laboratories in the Gambia. Kaplan-Meier estimates of survival were determined for mortality and virologic failure. A Cox proportional hazards model was used to identify baseline demographic, clinical, immunologic and virologic factors associated with increased risk of death.

RESULTS

The overall Kaplan-Meier estimate of survival to 36 months was 73.4% (66.5, 80.3). Survival was marginally higher in HIV-2-infected patients compared to HIV-1-infected patients; it was significantly higher in patients with a baseline CD4(+) lymphocyte cell count of greater than 50 cells/μl compared to those with a baseline CD4(+) count of less than 50 cells/μl. CD4(+) cell recovery was faster in HIV-1-infected individuals compared to HIV-2-infected patients up to 24 months, although this did not result higher mortality in the latter group. No differences in virologic failure were observed by HIV type.

CONCLUSION

HIV-1 and HIV-2-infected patients receiving ART in a clinical setting in the Gambia had good survival to 36 months. HIV-2-infected patients did as well as HIV-1-infected patients in terms of long-term immunological and virological responses and overall survival.

Memory and naive-like regulatory CD4+ T cells expand during HIV-2 infection in direct association with CD4+ T-cell depletion irrespectively of viremia

OBJECTIVE

The dynamics of CD4(+) regulatory T cells (Treg) during HIV-1 infection remains unclear. To further investigate Treg in this context, we characterized, for the first time, this population in HIV-2-positive individuals. Although both HIV infections are associated with hyperimmune activation and CD4(+) T-cell lymphopenia, most HIV-2-positive individuals display slower disease progression and low-to-undetectable viremia.

DESIGN/METHODS

Samples were obtained from cohorts of untreated HIV-2-positive and HIV-1-positive, treated HIV-1-positive and seronegative individuals. The proportion of CD4(+) T cells bearing a Treg phenotype, defined in terms of high-level CD25 or Foxp3 expression, was assessed by flow cytometry and correlated with markers of disease progression. The proportions of naive and memory-like subsets as well as cycling cells were determined.

RESULTS

We observed an increased proportion of Treg, associated with disease progression, as well as increased proportions of cycling (Ki67(+)) memory Treg, in untreated HIV-2-positive and HIV-1-positive individuals. We also noted an expansion of Treg that persisted over time in treated, immunologically discordant HIV-1-positive individuals, who, similarly to HIV-2-positive patients, present undetectable viremia and low CD4 T-cell count.

CONCLUSION

Overall, we demonstrated that Treg frequency was increased in all lymphopenic HIV-2-positive and HIV-1-positive individuals irrespective of the presence or absence of viremia or antiretroviral treatment. This, in turn, suggests that the observed alterations in Treg frequency in HIV/AIDS are more directly related to the degree of CD4 depletion than to viremia.

Immunovirological response to triple nucleotide reverse-transcriptase inhibitors and ritonavir-boosted protease inhibitors in treatment-naive HIV-2-infected patients: The ACHIEV2E Collaboration Study Group

BACKGROUND

Triple nucleoside reverse-transcriptase inhibitors (NRTIs) are recommended by the World Health Organization as first-line regimen in treatment-naïve HIV-2-infected patients. However, ritonavir-boosted protease inhibitor (PI/r)-containing regimens are frequently prescribed. In the absence of previous randomized trials, we retrospectively compared these regimens in observational cohorts.

METHODS

HIV-2-infected patients from 7 European cohorts who started triple NRTI or PI/r since January 1998 were included. Piecewise linear models were used to estimate CD4 cell count and plasma HIV-2 RNA level slopes, differentiating an early phase (until end of month 3) and a second phase (months 4-12). On-treatment analyses censored data at major treatment modification and systematically at month 12.

RESULTS

Forty-four patients started triple NRTI therapy and 126 started PI/r therapy. Overall, the median CD4 cell count was 191 cells/mm(3) and the median plasma HIV-2 RNA level was ≥2.7 log(10) copies/ml in 61% of the patients at combination antiretroviral therapy (cART) initiation; the median duration of the first cART was 20 months, not differing between groups. PI/r regimens were associated with better CD4 cell count and HIV-2 RNA level outcomes, compared with NRTI regimens. Estimated CD4 cell count slopes were +6 and +12 cells/mm(3)/month during the early phase (P = .22), and -60 cells/mm(3)/year versus +76 cells/mm(3)/year during the second phase (P = .002), for triple NRTI and PI/r, respectively. Estimated mean HIV-2 RNA levels at month 12 in patients with detectable viremia at cART initiation were 4.0 and 2.2 log(10) copies/ml, respectively (P = .005).

CONCLUSIONS

In this observational study, PI/r-containing regimens showed superior efficacy over triple NRTI regimens as first-line therapy in HIV-2-infected patients.

Clinical significance of HIV reverse-transcriptase inhibitor-resistance mutations

In this article, we summarize recent knowledge on drug-resistance mutations within HIV reverse transcriptase (RT). Several large-scale HIV-1 genotypic analyses have revealed that the most prevalent nucleos(t)ide analog RT inhibitor (NRTI)-resistance mutation is M184V/I followed by a series of thymidine analog-associated mutations: M41L, D67N, K70R, L210W, T215Y/F and K219Q/E. Among non-nucleoside RT inhibitor (NNRTI)-resistance mutations, K103N was frequently observed, followed by Y181C and G190A. Interestingly, V106M was identified in HIV-1 subtype C as a subtype-specific multi-NNRTI-resistance mutation. Regarding mutations in the HIV-1 RT C-terminal region, including the connection subdomain and RNase H domain, their clinical impacts are still controversial, although their effects on NRTI and NNRTI resistance have been confirmed in vitro. In HIV-2 infections, the high prevalence of the Q151M mutation associated with multi-NRTI resistance has been frequently observed.

Update on human immunodeficiency virus (HIV)-2 infection

Infection with human immunodeficiency virus type 2 (HIV-2) occurs mainly in West Africa, but an increasing number of cases have been recognized in Europe, India, and the United States. In this era of global integration, clinicians must be aware of when to consider the diagnosis of HIV-2 infection and how to test for this virus. Although there is debate regarding when therapy should be initiated and which regimen should be chosen, recent trials have provided important information on treatment options for HIV-2 infection. In this review, we present information on recent clinical advances in our understanding of HIV-2 infection and highlight remaining diagnostic and therapeutic challenges.