HIV-2 Infected Subjects Research Articles

Higher Type 1 Interferon Levels in Plasma of Asymptomatic HIV-2 than in HIV-1 Individuals

A number of cytokines are secreted during HIV infection that enhances both innate and adaptive immune responses. Interferon-α/β/γ, IL-12, IL-15 and IL-18 have been found to contribute to the development, maturation, differentiation and function of NK and other immune cells. The levels of IFN-α/β/γ, IL-12, IL-15 and IL-18 were compared in the plasma of 90 HIV-1 infected and 90 HIV-2 infected subjects by ELISA or Cytometric Beads Array assays. The HIV-infected subjects were stratified according to CD4+ T cell counts into three groups: >500, 200 - 500 and <200 cells/ul, with 30 subjects in each group. Cytokine levels were also determined in the plasma of 50 HIV uninfected blood bank donors. Among the cytokines tested, IFN-α was found to be significantly increased in HIV-2 infected compared to HIV-1 infected subjects at high CD4+ T cell counts (p = 0.001). The levels of IFN-β were seen to differ between the two infections in patients from the category of medium CD4+ T cell counts: this was significantly increased in HIV-2 infected patients (p < 0.001) as well as compared to uninfected controls (p = 0.001). The levels of IFN-γ were similar at all the CD4+ T cell categories except for an increase in HIV-2 infected patients at low CD4+ T cell counts (p = 0.02). The levels of these cytokines were similar in all HIV-1 subjects. Also, the level of IL-12p70 was similar between the two infections but significantly higher in HIV-2 at low compared to medium CD4+ T cells categories (p = 0.047). Similar to IFN-γ and IL-12p70, the levels of both IL-18 and IL-15 were found to be significantly higher in HIV-2 infected patients compared to HIV-1 at low CD4+ T cell counts (p < 0.05). These data show that there is variability in the levels of innate cytokines at different stages of HIV infection but the finding of increased IFN-α in HIV-2 infected asymptomatic subjects is consistent with the high innate NK responses previously noted at this stage of infection.

Differential Expressions of Selected Activating and Inhibitory Receptors on K562-Stimulated Natural Killer (NK) Cells in HIV-1 and HIV-2 Infections

Context: The functional activity of NK cells depends on the balance between the engagement of activating and inhibitory receptors on the cell surface with their ligands, which enables them to kill infected cells. Objectives: The aim of this study was to evaluate and compare expressions of selected activating and inhibitory receptors on stimulated NK cells in HIV-1 and HIV-2 infections. Methods: PBMCs were analysed for activating (NKp30, NKp44, NKp46) and inhibitory (CD158a, CD158b, p70) receptor expressions in 30 HIV-1, 30 HIV-2 and 30 HIV uninfected healthy control (HC) subjects by flow cytometry after stimulating with K562 cells. Results: There was an expression of other receptors following an already in vitro engagement of NK cells with K562 cells. Higher expression of the activating receptors, NKp44 (p = 0.029) and NKp46 (p = 0.032) on NK cells from HIV-2 compared to HIV-1 infected individuals but similar NKp30 expression (p = 0.980). The levels of expression of inhibitory receptor CD158a were similar between HIV-1 and HIV-2 infected subjects (p = 0.309) but there was significant up-regulation of inhibitory receptors p70 (p = 0.010) and CD158b (p = 0.05) in HIV-1 compared to HIV-2 subjects. Conclusion: Despite the in vitro engagement of NK cells with stimulating K562 cells, our data showed differential expressions of other selected activating and inhibitory receptors in HIV-1 and HIV-2 infected subjects.

The role of CD8+ T-cell responses in the pathogenesis of HIV-2, a naturally contained human retroviral infection

Background: While a significant proportion of HIV-2-infected individuals are asymptomatic and maintain undetectable viral loads (controllers), 15-20% progress to AIDS and are predicted by detectable viraemia. Identifying immune correlates that distinguish these two groups should provide insights into how a potentially pathogenic retrovirus can be naturally controlled. Methods: We performed a detailed study of HIV-2-specific cellular responses in a unique community cohort in Guinea-Bissau followed for over two decades. T-cell responses were compared between controllers (n 1⁄4 33) and viraemic subjects (n 1⁄4 27) using overlapping peptides, MHC class I tetramers and multi-parameter flow cytometry. Results: HIV-2 viral control was significantly associated with a high magnitude, polyfunctional Gag-specific CD8+ T-cell response, but not with greater perforin upregulation. This potentially protective HIV-2-specific response is surprisingly narrow. HIV-2 Gag-specific CD8+ T-cells are at an earlier stage of differentiation than CMV-specific CD8+ Tcells, do not contain high levels of cytolytic markers and exhibit low levels of activation and proliferation, representing distinct properties from CD8+ T-cells associated with HIV-1 control. Furthermore, comparison of viral capsid sequence data from HIV-1 and HIV-2 infected subjects in this cohort reveal limited T-cell driven changes in HIV-2, despite potent T-cell pressure. Conclusions: These data reveal the potential T-cell correlates of HIV-2 control and the detailed phenotype of virus-specific CD8+ T-cells in a naturally contained retroviral infection, which is distinct from descriptions of CD8+ T-cell populations in HIV-1 infected elite controllers. The lack of potential T-cell escape in HIV-2 may be a significant factor in the benign course of infection seen in most HIV-2 infected subjects. http://dx.doi.org/10.1016/j.jinf.2013.07.006 HIV CONTROL IN POST-PARTUM MOTHERS; A

Are Plasma Biomarkers of Immune Activation Predictive of HIV Progression: A Longitudinal Comparison and Analyses in HIV-1 and HIV-2 Infections?

BackgroundChronic immune activation is a hallmark of HIV infection and has been associated with disease progression. Assessment of soluble biomarkers indicating immune activation provide clues into pathogenesis and hold promise for the development of point-of-care monitoring of HIV in resource-poor-settings. Their evaluation in cohort resources is therefore needed to further their development and use in HIV research.Methodology/Principal FindingsLongitudinal evaluation of βeta-2 microglobulin (β-2 m), neopterin and suPAR soluble urokinase-type plasminogen activator receptor (suPAR) was performed with archived plasma samples to predict disease progression and provided the first direct comparison of levels in HIV-1 and HIV-2 infections. At least 2095 samples from 137 HIV-1 and 198 HIV-2 subjects with starting CD4% of ≥28 and median follow up of 4 years were analysed. All biomarkers were correlated negatively to CD4% and positively to viral load and to each other. Analyses in subjects living for ≥5 years revealed increases in median β-2 m and neopterin and decreases in CD4% over this period and the odds of death within 5 years were positively associated with baseline levels of β-2 m and neopterin. ROC analyses strengthened the evidence of elevation of biomarkers in patients approaching death in both HIV-1 and HIV-2 infections. Regression models showed that rates of biomarker fold change accelerated from 6–8 years before death with no significant differences between biomarker levels in HIV-1 and HIV-2 at equal time points prior to death.An ‘immune activation index’ analysis indicative of biomarker levels at equivalent viral loads also showed no differences between the two infections.Conclusions/SignificanceOur results suggest that β-2 m and neopterin are useful tools for disease monitoring in both HIV-1 and HIV-2 infections, whereas sUPAR performed less well. Levels of immune activation per amount of virus were comparable in HIV-1 and HIV-2 infected subjects.

Greater Expansion of IFN-&amp;lt;i&amp;gt;γ&amp;lt;/i&amp;gt;&amp;lt;sup&amp;gt;﹣&amp;lt;/sup&amp;gt; CD4&amp;lt;sup&amp;gt;+&amp;lt;/sup&amp;gt; NKT Cells in HIV-1 Compared with HIV-2-Infected Subjects with Preserved CD4&amp;lt;sup&amp;gt;+&amp;lt;/sup&amp;gt; T Cell Counts

Context: Human Natural Killer T cells are T lymphocytes that express an invariant αβ T cells receptors and NK cells receptors. They regulate innate and adaptive immune response but are susceptible to HIV-1 infection. Objective: We compare the frequency and the activity of NKT cells in HIV-1 and HIV-2 infected individuals with CD4+ counts greater than 500/mm3 using flow cytometry after overnight stimulation with phytohemagglutinin (PHA). Results: The frequency of NKT cells was similar between both groups and also to sero-negative control subjects. There were also no significant differences in the proportions of total NKT cells and the CD4+ NKT subset that secreted interferon gamma (IFN-γ) after polyclonal stimulation. However, there was a significantly higher frequency of IFN-γ﹣ CD4+ NKT cells in HIV-1-infected compared with HIV-2 infected subjects (p = 0.043). Conclusion: These data suggest there is no relationship between the functional activity of NKT cell subsets and the total NKT cell population in HIV infection. The expansion of IFN-γ﹣ CD4+ NKT cells in HIV-1 infection may serve as target for viral infection and may eventually result in their depletion during chronic infection.

HTLV-1 and HIV-2 Infection Are Associated with Increased Mortality in a Rural West African Community

BackgroundSurvival of people with HIV-2 and HTLV-1 infection is better than that of HIV-1 infected people, but long-term follow-up data are rare. We compared mortality rates of HIV-1, HIV-2, and HTLV-1 infected subjects with those of retrovirus-uninfected people in a rural community in Guinea-Bissau.MethodsIn 1990, 1997 and 2007, adult residents (aged ≥15 years) were interviewed, a blood sample was drawn and retroviral status was determined. An annual census was used to ascertain the vital status of all subjects. Cox regression analysis was used to estimate mortality hazard ratios (HR), comparing retrovirus-infected versus uninfected people.ResultsA total of 5376 subjects were included; 197 with HIV-1, 424 with HIV-2 and 325 with HTLV-1 infection. The median follow-up time was 10.9 years (range 0.0–20.3). The crude mortality rates were 9.6 per 100 person-years of observation (95% confidence interval 7.1-12.9) for HIV-1, 4.1 (3.4–5.0) for HIV-2, 3.6 (2.9–4.6) for HTLV-1, and 1.6 (1.5–1.8) for retrovirus-negative subjects. The HR comparing the mortality rate of infected to that of uninfected subjects varied significantly with age. The adjusted HR for HIV-1 infection varied from 4.0 in the oldest age group (≥60 years) to 12.7 in the youngest (15–29 years). The HR for HIV-2 infection varied from 1.2 (oldest) to 9.1 (youngest), and for HTLV-1 infection from 1.2 (oldest) to 3.8 (youngest).ConclusionsHTLV-1 infection is associated with significantly increased mortality. The mortality rate of HIV-2 infection, although lower than that of HIV-1 infection, is also increased, especially among young people.

Undetectable plasma viral load predicts normal survival in HIV-2-infected people in a West African village

BackgroundThere have been no previous studies of the long-term survival and temporal changes in plasma viral load among HIV-2 infected subjects.Methods133 HIV-2 infected and 158 HIV-uninfected subjects from a rural area in North-west Guinea-Bissau, West Africa were enrolled into a prospective cohort study in 1991 and followed-up to mid-2009. Data were collected on four occasions during that period on HIV antibodies, CD4% and HIV-2 plasma viral load.ResultsMedian age (interquartile range [IQR]) of HIV-2 infected subjects at time of enrollment was 47 (36, 60) years, similar to that of HIV-uninfected control subjects, 49 (38, 62) (p = 0.4). Median (IQR) plasma viral load and CD4 percentage were 347 (50, 4,300) copies/ml and 29 (22, 35) respectively.Overall loss to follow-up to assess vital status was small, at 6.7% and 6.3% for HIV-2 infected and uninfected subjects respectively. An additional 17 (12.8%) and 16 (10.1%) of HIV-2 infected and uninfected subjects respectively were censored during follow-up due to infection with HIV-1. The mortality rate per 100 person-years (95% CI) was 4.5 (3.6, 5.8) among HIV-2 infected subjects compared to 2.1 (1.6, 2.9) among HIV-uninfected (age-sex adjusted rate ratio 1.9 (1.3, 2.8, p < 0.001) representing a 2-fold excess mortality rate associated with HIV-2 infection.Viral load measurements were available for 98%, 78%, 77% and 61% HIV-2 infected subjects who were alive and had not become super-infected with HIV-1, in 1991, 1996, 2003 and 2006 respectively. Median plasma viral load (RNA copies per ml) (IQR) did not change significantly over time, being 150 (50, 1,554; n = 77) in 1996, 203 (50, 2,837; n = 47) in 2003 and 171 (50, 497; n = 31) in 2006. Thirty seven percent of HIV-2 subjects had undetectable viraemia (<100 copies/ml) at baseline: strikingly, mortality in this group was similar to that of the general population.ConclusionsA substantial proportion of HIV-2 infected subjects in this cohort have stable plasma viral load, and those with an undetectable viral load (37%) at study entry had a normal survival rate. However, the sequential laboratory findings need to be interpreted with caution given the number of individuals who could not be re-examined.

Comparison of Cytotoxic activity and Interferon-g secretion by Natural Killer Cells in HIV-1 and HIV-2 infected individuals

Methods In this study peripheral blood mononuclear cells were obtained from 30 HIV-1 and 30 HIV-2 infected subjects from each of 3 categories of CD4 T-cell counts (>500, 200-500 and <200 cells/ul) together with 50 HIV uninfected control subjects. Lytic activity and IFN-g secretion by NK cells from HIV-1 and HIV-2 infected subjects were measured by chromium-release and ELISPOT assays respectively following incubation of PBMC with the NK-sensitive K562 cells. Viral load was also measured from the plasma samples of the subjects.

An adaptation of recombinant vaccinia-based ELISPOT and intracellular cytokine staining for a comparative measurement of cellular immune responses in HIV-1 and HIV-2 infections in West Africa

An efficient and quantitative tool for rapid assessment of human immunodeficiency virus (HIV)-induced cellular immune responses is important for resource-limited settings, such as in sub-Saharan Africa. Modifications are required to previously reported methods for evaluating ex-vivo antigen-specific cellular responses based on direct recombinant vaccinia virus (rVV) stimulation of peripheral blood mononuclear cells (PBMCs) by enzyme linked immunosorbent assay (ELISPOT) and by flow cytometry intracellular cytokine assay (ICA). We made such modifications in order to detect specific responses and compared quantitative cellular immune responses in HIV-1 and HIV-2 infected Gambians. The sensitivity of the rVV-based ELISPOT assay was on average 1.25 interferon (IFN)-gamma spot forming cells (SFC) per 50 000 PBMCs specific for either infection, and 5 IFN-gamma-secreting CD8+ T cells/50 000 in the ICA. The level of IFN-gamma SFC detected by ELISPOT and by ICA were correlated (P < 0.02). ICA detected pol-specific responses in 88% and 67% of HIV-1 and HIV-2 subjects, respectively, and gag-specific responses in more than 80% of both infections. Lower proportions of responders were obtained with ELISPOT, for which pol responses were present in 60% of HIV-1 and 46% of HIV-2 infected patients, and gag responses in 55% and 69%, respectively. The assays did not show any significant difference in cellular immune responses between HIV-1 and HIV-2 infected subjects with CD4% >or= 20%. These outcomes are comparable with results obtained using standard techniques and thus this method is a suitable, rapid and less expensive assessment of cellular immunity.

High frequency of selection of K65R and Q151M mutations in HIV-2 infected patients receiving nucleoside reverse transcriptase inhibitors containing regimen.

The objective of the study was to determine retrospectively which substitutions in the reverse transcriptase (RT) gene are selected in vivo during nucleoside RT inhibitors (NRTI) containing regimen in HIV-2 infected subjects. Thirty-four HIV-2 patients having received NRTI-containing regimen with available specimens and amplifiable RT gene were studied. Analyses of RT gene were undertaken after a median NRTI exposure of 51 months (range: 5-128). Mutations at positions known to be involved in HIV-1 resistance were observed in 26/34 patients. Selection of Q151M mutation was observed in nine out of 34 isolates (26%) after a median NRTIs exposure of 41 months (range: 12-77). In 8/9 cases, Q151M mutation was associated with other substitutions at positions known to be involved in HIV-1 resistance: K65R (n = 6), D67N (n = 1), N69S or T (n = 2), K70R (n = 3), M184V (n = 4), S215Y (n = 1). Compared with HIV-1 infection, there is a high frequency of selection of Q151M mutation in HIV-2 infected patients receiving various combinations of NRTIs. In these highly thymidine analogue pretreated patients, the selection of thymidine analogue mutations was low suggesting that the pathway to resistance is very different between these two viruses.

T‐helper reactivity to simian immunodeficiency virus gag synthetic peptides in human immunodeficiency virus type 2 infected individuals

West African populations are infected with divergent strains of human immunodeficiency virus type 2 (HIV2), some of which are closely related to simian immunodeficiency virus (SIV) and it has been postulated that the HIV2 epidemic might have arisen by cross-species spread of SIV into the human population in West Africa. To gain some insight into the possible basis for cross protection between these two closely related viruses, the T-helper responses to 15 synthetic peptides from SIV gag synthetic peptides were investigated in seven HIV2-infected subjects and in seven healthy controls. Significant reactivity to at least one of the synthetic peptides tested was found in all patients and a statistically significant correlation between CD4+ lymphocyte absolute numbers and the number of reacting peptides was observed. A marginal lymphocyte reactivity was found in two of the healthy controls studied. In conclusion, this preliminary evidence that HIV2-infected patients exhibit T-cell responses to SIV gag peptides suggests that both viruses share t-helper epitopes in the gag viral region and raises the possibility of cross protection between SIV and HIV2 which may be relevant for HIV2 vaccine research based on closely related retroviruses.

HIV 2 infection among blood donors and other subjects in France. The "Retrovirus" Study Group of the French Society of Blood Transfusion.

During a 3 year period, from August 1985 to August 1988, 18 HIV 2-infected blood donors were detected in France as a result of systematic HIV 1 screening. These sera were characterized as HIV 2 by specific Western blot and synthetic peptides. Within the same period, 40 other HIV 2 infected subjects were identified by our study group, independently of blood donations. Thirty of these 58 subjects living in France originate from West Africa (8 blood donors), 3 (I blood donor) are Portuguese men who had lived in West Africa and 25 (9 blood donors) are of French origin; among these, 16 have had a known close contact with West Africa. When HIV 2-infected subjects were asymptomatic, cross reactivity between antibodies to HIV 2 and HIV 1 proteins was generally observed with the two-step ELISA assays using total HIV 1 proteins; it was poor with the competitive assays and variable with the assays using recombinant proteins. When the subjects had signs of immunodeficiency, cross reactivity decreased. The data confirm that HIV 2 is not widespread in France and that most of HIV 2-infected but asymptomatic subjects are recognized by several HIV 1 ELISA assays. Accordingly, systematic screening for HIV 2 with an additional test cannot be recommended at the present time, but a combined HIV 1 and HIV 2 test will be useful when available.