Correlation between gag-specific CD8 T-cell responses, viral load, and CD4 count in HIV-1 infection is dependent on disease status

Helios expressing regulatory T cells are correlated with decreased IL-2 producing CD8 T cells and antibody diversity in Mozambican individuals living chronically with HIV-1

Background

Human immunodeficiency virus type 1 (HIV-1) causes impairment of T and B cell responses, which begins during the acute phase of infection and is not completely restored by antiretroviral treatment. Regulatory T cell (Tregs) can improve overall disease outcome by controlling chronic inflammation but may also suppress beneficial HIV-1 specific immune responses. We aimed to analyze the profile of Tregs and their correlation with the status of T cells activation, the expression of IL-2 and IFNγ and the profile of HIV-1 specific antibodies response in Mozambican people living chronically with HIV-1 (PLWH-C).

Results

In PLWH-C, the proportion of total Tregs was positively correlated with the proportion of IL-2⁺CD4 T cells (r = 0.647; p = 0.032) and IL-2⁺IFNγ⁺CD8 T cells (r = 0.551; p = 0.014), while the proportions of Helios⁺Tregs correlated inversely with levels of IL-2⁺CD8 T cells (r = − 0.541; p = 0.017). Overall, PLWH-C, with (82%) or without virologic suppression (64%), were seronegative for at least HIV-1 p31, gp160 or p24, and the breadth of antibody responses was positively correlated with proportions of CD38⁺HLA-DR⁺CD8 T cells (r = 0.620; p = 0.012), viral load (r = 0.452; p = 0.040) and inversely with absolute CD4 T cells count (r = − 0.481; p = 0.027). Analysis of all individuals living HIV-1 showed that the breadth of HIV-1 antibody responses was inversely correlated with the proportion of Helios⁺Tregs (r = − 0.45; p = 0.02).

Conclusion

Among Mozambican people living with HIV-1, seronegativity to some HIV-1 proteins is common, particularly in virologically suppressed individuals. Furthermore, lower diversity of HIV-specific antibodies is correlated to lower immune activation, lower viral replication and higher CD4 counts, in PLWH-C. Elevation in the proportion of Helios⁺Tregs is related to a reduction of CD8 T expressing intracellular IL-2, in PLWH-C, but may contribute to impairment of B cell function.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00487-3.

A heterologous prime-boosting strategy with replicating Vaccinia virus vectors and plant-produced HIV-1 Gag/dgp41 virus-like particles

Showing modest efficacy, the RV144 HIV-1 vaccine clinical trial utilized a non-replicating canarypox viral vector and a soluble gp120 protein boost. Here we built upon the RV144 strategy by developing a novel combination of a replicating, but highly-attenuated Vaccinia virus vector, NYVAC-KC, and plant-produced HIV-1 virus-like particles (VLPs). Both components contained the full-length Gag and a membrane anchored truncated gp41 presenting the membrane proximal external region with its conserved broadly neutralizing epitopes in the pre-fusion conformation. We tested different prime/boost combinations of these components in mice and showed that the group primed with NYVAC-KC and boosted with both the viral vectors and plant-produced VLPs have the most robust Gag-specific CD8 T cell responses, at 12.7% of CD8 T cells expressing IFN-γ in response to stimulation with five Gag epitopes. The same immunization group elicited the best systemic and mucosal antibody responses to Gag and dgp41 with a bias towards IgG1.

Human leucocyte antigen-Bw4 and Gag-specific T cell responses are associated with slow disease progression in HIV-1B-infected anti-retroviral therapy-naive Chinese

In China, the majority of human immunodeficiency virus (HIV) infections are predominately subtype B. It is important to characterize the HIV-1 subtype B-specific and its T cell response within the Chinese population, with the aim of identifying protective correlates of immunity to control HIV-1 infections. In this study, we performed a comprehensive analysis looking into the magnitude/strength of T cell responses directed at the Gag protein of the HIV-1 subtype B, one of the most conserved HIV-1 proteins. The study group consisted of anti-retroviral native and chronic HIV-1 subtype B-infected individuals. We used enzyme-linked immunospot (ELISPOT) assay to quantify the total T cell responses to HIV-1 Gag at the single peptide level. Twenty-eight (38%) peptides were recognized in 24 (82·8%) individuals. The p24 was identified as the most frequently recognized subunit protein with the greatest T cell response in the test, which correlated positively with CD4(+) T cell count and inversely with viral load (VL). At the level of the human leucocyte antigen (HLA) supertypes, we detected the highest levels and a significant correlation with both the CD4(+) T cell count and the VL with Gag T cell responses in Bw4/Bw4. These findings demonstrate that (i) the HIV-1B Gag p24-specific immune responses play an important role in controlling viral replication and slowing clinical progression; and (ii) HLA-Bw4/Bw4 allele has stronger T cell responses, which is associated with slow clinical progression in Chinese HIV patients.

HIV-specific IL-2(+) and/or IFN-γ(+) CD8(+) T cell responses during chronic HIV-1 infection in former blood donors

OBJECTIVE

Conflicting data have been generated from previous studies to determine which kind of relationship exists between HIV-1 specific CD8 Tcell responses and HIV-1 viral load or CD4 count over the course of infection. In this study, 153 HIV-1 infected LTNPs were enrolled to investigate the role of HIV-1 specific CD8 T-cell responses in chronic HIV-1 infection among HIV-1 infected former blood donors.

METHODS

The patients were stratified into three groups according to CD4 count: CD4≥500 cells/μL; 350 cells/μL≤CD4<500 cells/μL; CD4<350 cells/μL. PBMCs were isolated from the patients' anticoagulated blood samples. IL-2 and IFN-γ secretions of CD 8 T cells against 17 HIV-1 consensus B full peptide pools were analyzed by using ICS assay.

RESULTS

An overall inverse correlation were observed between CD4 count and plasma viral load. Although no significant difference was observed during the comparisons of frequency/breadth of HIV-1 specific CD8 T cell responses, CD4 count stratification analysis showed that different correlation pattern existed in three strata: as for patients whose CD4 counts were less than 350 cells/μL, no significant correlations were identified between frequency/breadth of HIV-1 specific CD8 T cell responses and CD4 count/viral load; as for patients whose CD4 counts ranged from 350 cells/μL to 500 cells/μL, significant correlation was only observed between the response breadth of IL-2+IFN-γ+ CD8 T cells and CD4 count; however, as for patients whose CD4 counts were more than 500 cells/μL, direct correlations were identified between IL-2+IFN-γ+/IL-2+/IFN-γ+ CD8 T cells and viral load or CD4 count.

CONCLUSIONS

Universal consistent inverse correlation was only indentified between CD4 count and viral load. The relationship between HIV-1 specific CD8 T cell responses and CD4 count/viral load varied in different CD4 strata, which showed that better preserved CD4 T cells were correlated with better CD8 T cell functions.

Acute mucosal pathogenesis of feline immunodeficiency virus is independent of viral dose in vaginally infected cats

BACKGROUND

The mucosal pathogenesis of HIV has been shown to be an important feature of infection and disease progression. HIV-1 infection causes depletion of intestinal lamina propria CD4+ T cells (LPL), therefore, intestinal CD4+ T cell preservation may be a useful correlate of protection in evaluating vaccine candidates. Vaccine studies employing the cat/FIV and macaque/SIV models frequently use high doses of parenterally administered challenge virus to ensure high plasma viremia in control animals. However, it is unclear if loss of mucosal T cells would occur regardless of initial viral inoculum dose. The objective of this study was to determine the acute effect of viral dose on mucosal leukocytes and associated innate and adaptive immune responses.

RESULTS

Cats were vaginally inoculated with a high, middle or low dose of cell-associated and cell-free FIV. PBMC, serum and plasma were assessed every two weeks with tissues assessed eight weeks following infection. We found that irrespective of mucosally administered viral dose, FIV infection was induced in all cats. However, viremia was present in only half of the cats, and viral dose was unrelated to the development of viremia. Importantly, regardless of viral dose, all cats experienced significant losses of intestinal CD4+ LPL and CD8+ intraepithelial lymphocytes (IEL). Innate immune responses by CD56+CD3- NK cells correlated with aviremia and apparent occult infection but did not protect mucosal T cells. CD4+ and CD8+ T cells in viremic cats were more likely to produce cytokines in response to Gag stimulation, whereas aviremic cats T cells tended to produce cytokines in response to Env stimulation. However, while cell-mediated immune responses in aviremic cats may have helped reduce viral replication, they could not be correlated to the levels of viremia. Robust production of anti-FIV antibodies was positively correlated with the magnitude of viremia.

CONCLUSIONS

Our results indicate that mucosal immune pathogenesis could be used as a rapid indicator of vaccine success or failure when combined with a physiologically relevant low dose mucosal challenge. We also show that innate immune responses may play an important role in controlling viral replication following acute mucosal infection, which has not been previously identified.

Impact of select immunologic and virologic biomarkers on CD4 cell count decrease in patients with chronic HIV-1 subtype C infection: results from Sinikithemba Cohort, Durban, South Africa

BACKGROUND

The extent to which immunologic and clinical biomarkers influence human immunodeficiency virus type 1 (HIV-1) infection outcomes remains incompletely characterized, particularly for non-B subtypes. On the basis of data supporting in vitro HIV-1 protein-specific CD8 T lymphocyte responses as correlates of immune control in cross-sectional studies, we assessed the relationship of these responses, along with established HIV-1 biomarkers, with rates of CD4 cell count decrease in individuals infected with HIV-1 subtype C.

METHODS

Bivariate and multivariate mixed-effects models were used to assess the relationship of baseline CD4 cell count, plasma viral load, human leukocyte antigen (HLA) class I alleles, and HIV-1 protein-specific CD8 T cell responses with the rate of CD4 cell count decrease in a longitudinal population-based cohort of 300 therapy-naive, chronically infected adults with baseline CD4 cell counts >200 cells/mm(3) and plasma viral loads >500 copies/mL over a median of 25 months of follow-up.

RESULTS

In bivariate analyses, baseline CD4 cell count, plasma viral load, and possession of a protective HLA allele correlated significantly with the rate of CD4 cell count decrease. No relationship was observed between HIV-1 protein-specific CD8 T cell responses and CD4 cell count decrease. Results from multivariate models incorporating baseline CD4 cell counts (201-350 vs >350 cells/mm(3)), plasma viral load (< or =100,000 vs >100,000 copies/mL), and HLA (protective vs not protective) yielded the ability to discriminate CD4 cell count decreases over a 10-fold range. The fastest decrease was observed among individuals with CD4 cell counts >350 cells/mm(3) and plasma viral loads >100,000 copies/mL with no protective HLA alleles (-59 cells/mm(3) per year), whereas the slowest decrease was observed among individuals with CD4 cell counts 201-350 cells/mm(3), plasma viral loads < or =100,000 copies/mL, and a protective HLA allele (-6 cells/mm(3) per year).

CONCLUSIONS

The combination of plasma viral load and HLA class I type, but not in vitro HIV-1 protein-specific CD8 T cell responses, differentiates rates of CD4 cell count decrease in patients with chronic subtype-C infection better than either marker alone.

Reference ranges and age-related changes of peripheral blood lymphocyte subsets in Chinese healthy adults

This study was performed to build region-specific reference ranges of peripheral blood lymphocyte subsets for Chinese healthy adults from the young to the elderly and analyze the trends of changes in lymphocyte subsets for evaluating the impact of age on the values. 151 healthy adults aged 19-86 were recruited based on the SENIEUR protocol. Three sets of reference ranges were finally built applicable for the healthy young (19-44 years), middle-aged (45-64 years) and elder adults ([Symbol: see text]65). Comparisons in parameters among the three cohorts showed that a statistically significant increase in CD16CD56+ NK cell was observed between the middle-aged and elder cohorts, whereas for the majority of the parameters, a significant decline was observed between the young and the middle-aged cohorts. Further results showed that inverse correlations were observed between the age and CD19(+) B, CD3(+) T, CD3(+)CD4(+) T, CD4(+)CD45RA(+)CD62L(+) naïve T cell and CD4(+)CD28(+)/CD4(+), while the positive one was identified between the age and the NK cell. These significant changes of the most of immune parameters provided evidence for immunosenescence. Notably, T cell activation markers of CD8(+)CD38(+) and CD8(+)HLA-DR(+) showed reverse trends of association with age, which provides a clue for further researches on the mechanisms underlying the paradoxical clinical presentation of the elder patients.

Viral fitness implications of variation within an immunodominant CD8+ T-cell epitope of HIV-1

Cytotoxic T-lymphocyte (CTL) epitopes within the HIV genome are subject to negative and positive selective pressures, the balance of which influences CTL escape at a given epitope. We investigated whether viral fitness requirements dictate conservation of the HLA-A2 restricted immunodominant epitope SLYNTVATL (SL9). Viral clones incorporating changes throughout the SL9 epitope region were compared to consensus SL9 virus in terms of replication kinetics and relative viral fitness. Constructs recapitulating in vivo SL9-CTL escape variants showed markedly little effect on replication and fitness, as did non-natural conservative mutations targeting immunologically relevant positions of the epitope. Although certain residues of the epitope were constrained by viral requirements, our research reveals that there are multiple SL9 variants that are well tolerated virologically but fail to arise in vivo. In light of this data, assumptions regarding the balance of immune and viral selective pressures on this immunodominant epitope sequence need to be reassessed.

Host HLA B*allele-associated multi-clade Gag T-cell recognition correlates with slow HIV-1 disease progression in antiretroviral therapy-naïve Ugandans

BACKGROUND

Some HIV infected individuals remain asymptomatic for protracted periods of time in the absence of antiretroviral therapy (ART). Virological control, CD4 T cell loss and HIV-specific responses are some of the key interrelated determinants of HIV-1 disease progression. In this study, possible interactions between viral load, CD4 T cell slopes, host genetics and HIV-specific IFN-gamma responses were evaluated in chronically HIV-1-infected adults.

METHODOLOGY/PRINCIPAL FINDINGS

Multilevel regression modeling was used to stratify clade A or D HIV-infected individuals into disease progression groups based on CD4 T cell slopes. ELISpot assays were used to quantify the frequency and magnitude of HIV-induced IFN-gamma responses in 7 defined rapid progressors (RPs) and 14 defined slow progressors (SPs) at a single time point. HLA typing was performed using reference strand conformational analysis (RSCA). Although neither the breadth nor the magnitude of the proteome-wide HIV-specific IFN-gamma response correlated with viral load, slow disease progression was associated with over-representation of host immunogenetic protective HLA B* alleles (10 of 14 SPs compared to 0 of 7; p = 0.004, Fisher's Exact) especially B*57 and B*5801, multiclade Gag T-cell targeting (71%, 10 of 14 SPs compared to 14%, 1 of 7 RPs); p = 0.029, Fisher's Exact test and evident virological control (3.65 compared to 5.46 log10 copies/mL in SPs and RPs respectively); p<0.001, unpaired student's t-test

CONCLUSIONS

These data are consistent with others that associated protection from HIV disease with inherent host HLA B allele-mediated ability to induce broader Gag T-cell targeting coupled with apparent virological control. These immunogenetic features of Gag-specific immune response which could influence disease progression may provide useful insight in future HIV vaccine design.

Nef modulates the immunogenicity of Gag encoded in a non-infectious HIV DNA vaccine

Gag-CD8+ T cell responses are associated with immune control of HIV infection. Since during HIV infection Nef impairs T cell responses, we evaluated whether deletion of nef from a non-infectious HIV DNA vaccine (Delta4 Nef+), creating Delta5 Nef(-), would affect its immunogenicity. When compared with Delta4, mice injected with Delta5 developed significantly lower CD8+ T cell responses to Gag, but no significant change in the responses to Env was observed. In vitro, deletion of Nef abrogated the induced cell death, production of virus-like particles and release of Gag from transfected cells. Thus, the effect of Nef in causing extrusion of Gag might adjuvant the CD8+ T cell responses to Gag in DNA vaccine.

Human immunodeficiency virus type 1 specific cytotoxic T lymphocyte responses in Chinese infected with HIV-1 B'/C Recombinant (CRF07_BC)

BACKGROUND

The characterization of HIV-1-specific T cell responses in people infected with locally circulating HIV-1 strain will facilitate the development of HIV-1 vaccine. Sixty intravenous drug users infected with HIV-1 circulating recombinant form 07_BC (CRF07_BC), which has been spreading rapidly in western China from north to south, were recruited from Xinjiang, China to assess the HIV-1-specific T cell responses at single peptide level with overlapping peptides (OLP) covering the whole concensus clades B and C proteome.

RESULTS

The median of the total magnitude and total number of OLPs recognized by CTL responses were 10925 SFC/million PBMC and 25 OLPs, respectively, when tested by clade C peptides, which was significantly higher than when tested by clade B peptides. The immunodominant regions, which cover 14% (58/413) of the HIV-1 proteome, are widely distributed throughout the HIV-1 proteome except in Tat, Vpu and Pol-PR, with Gag, Pol-RT, Pol-Int and Nef being most frequently targeted. The subdominant epitopes are mostly located in p24, Nef, integrase, Vpr and Vif. Of the responses directed to clade C OLPs, 61.75% (972/1574) can be observed when tested with corresponding clade B OLPs. However, Pol-PR and Vpu tend to be targeted in the clade B sequence rather than the clade C sequence, which is in line with the recombinant pattern of CRF07_BC. Stronger and broader CTL responses in subjects with CD4 cell counts ranging from 200 to 400/mm3 were observed when compared to those with less than 200/mm3 or more than 400/mm3, though there have been no significant correlations identified between the accumulative CTL responses or overall breadth and CD4 cell count or plasma viral load.

CONCLUSION

This is the first study conducted to comprehensively address T cell responses in Chinese subjects infected with HIV-1 CRF07_BC in which subtle differences in cross-reactivity were observed, though similar patterns of overall immune responses were demonstrated with clade B infected populations. The immunodominant regions identified in this population can facilitate future HIV-1 vaccine development in China.

Long-term nonprogression of HIV infection in children: evaluation of the ANRS prospective French Pediatric Cohort

BACKGROUND

Some children who are infected with human immunodeficiency virus type 1 (HIV-1) during the perinatal period remain asymptomatic for very long periods in the absence of antiretroviral treatment, as is the case for some adults. Our objective was to estimate the proportion of children who developed neither symptoms nor major immunological perturbations to the age of > or = 10 years in a prospective cohort of infected children who had been observed since birth.

METHODS

The ongoing prospective French Pediatric Cohort includes 568 HIV-1-infected children. Here, we report the follow-up data for all 348 HIV-1-infected children who were born before 1 January 1994. Children with long-term nonprogression of infection (LTNPs) were defined as HIV-1-infected children who had been observed for at least 10 years, never received antiretroviral treatment other than zidovudine monotherapy, never developed symptoms of Centers for Disease Control and Prevention clinical category C or B, and had a CD4+ cell percentage of < 25% no more than once during follow-up. Other definitions were compared.

RESULTS

The Kaplan-Meier estimate of long-term nonprogression was 2.4% (95% confidence interval, 1.1%-4.6%) at 10 years of age, and 7 children were classified as LTNPs. The Kaplan-Meier estimates decreased slightly with age, to 1.8% at 12 years of age and 1.4% at 14 years of age. Plasma HIV-1 replication rates were low (< 1000 copies RNA/mL) for 2 of the 7 LTNPs at the age of 10 years (0.6% of the total denominator). None of the routinely measured maternal or perinatal markers were significantly linked to long-term nonprogression, with the exception of the mother's Centers for Disease Control and Prevention clinical category at the time of delivery.

CONCLUSIONS

Approximately 2% of children who were infected during the perinatal period displayed no immunological or clinical progression by the age of 10 years. This figure is close to that reported for adults in studies that have used similar definitions.