Peripheral lymphocytes of clinically non-progressor patients harbor inactive and uninducible HIV proviruses

Robust HIV-specific CD4+ and CD8+ T-cell responses distinguish elite control in adolescents living with HIV from viremic nonprogressors

BACKGROUND

Elite controllers are therapy-naive individuals living with HIV capable of spontaneous control of plasma viraemia for at least a year. Although viremic nonprogressors are more common in vertical HIV-infection than in adults' infection, elite control has been rarely characterized in the pediatric population.

DESIGN

We analyzed the T-cell immunophenotype and the HIV-specific response by flow cytometry in four pediatric elite controllers (PECs) compared with age-matched nonprogressors (PNPs), progressors and HIV-exposed uninfected (HEUs) adolescents.

RESULTS

PECs T-cell populations had lower immune activation and exhaustion levels when compared with progressors, reflected by a more sustained and preserved effector function. The HIV-specific T-cell responses among PECs were characterized by high-frequency Gag-specific CD4+ T-cell activity, and markedly more polyfunctional Gag-specific CD8+ activity, compared with PNPs and progressors. These findings were consistently observed even in the absence of protective HLA-I molecules such as HLA-B∗27/57/81.

CONCLUSION

Pediatric elite control is normally achieved after years of infection, and low immune activation in PNPs precedes the increasing ability of CD8+ T-cell responses to achieve immune control of viraemia over the course of childhood, whereas in adults, high immune activation in acute infection predicts subsequent CD8+ T-cell mediated immune control of viremia, and in adult elite controllers, low immune activation is therefore the consequence of the rapid CD8+ T-cell mediated immune control generated after acute infection. This distinct strategy adopted by PECs may help identify pathways that facilitate remission in posttreatment controllers, in whom protective HLA-I molecules are not the main factor.

HIV-specific CD4+ T cells may contribute to viral persistence in HIV controllers

BACKGROUND

Human immunodeficiency virus (HIV)--infected individuals maintaining plasma HIV RNA levels <75 copies/mL in the absence of therapy ("HIV controllers") often maintain high HIV-specific T cell responses, which likely contribute to the control of viral replication. Despite robust immune responses, these individuals never eradicate HIV infection. We hypothesized that HIV-specific CD4(+) T cells might serve as target cells for HIV, contributing to viral persistence in this setting.

METHODS

We measured frequencies of activated (CD38(+) HLA-DR(+)) and HIV Gag-specific CD4(+) and CD8(+) T cells and plasma- and cell-associated levels of HIV RNA and DNA in a cohort of 38 HIV controllers.

RESULTS

Although there was no evidence of a relationship between the extent of low-level viremia and the frequency of either activated or HIV-specific CD4(+) T cells, controllers with higher HIV-specific CD4(+) T cell frequencies had higher cell-associated HIV DNA levels (ρ = 0.53; P = .019). Higher activated CD4+ T cell frequencies were also associated with higher levels of cell-associated DNA (P = .027) and RNA (P = .0096). However, there was no evidence of a relationship between cell-associated HIV RNA or DNA levels and HIV-specific CD8(+) T cell frequencies.

CONCLUSIONS

These data support a model in which strong HIV-specific CD4(+) T cell responses in HIV controllers, while contributing to a potent adaptive immune response, may also contribute to viral persistence, preventing the natural eradication of HIV infection.

Infrequent recovery of HIV from but robust exogenous infection of activated CD4(+) T cells in HIV elite controllers

BACKGROUND. Human immunodeficiency virus (HIV) elite controllers are able to control infection with HIV-1 spontaneously to undetectable levels in the absence of antiretroviral therapy, but the mechanisms leading to this phenotype are poorly understood. Although low frequencies of HIV-infected peripheral CD4(+) T cells have been reported in this group, it remains unclear to what extent these are due to viral attenuation, active immune containment, or intracellular host factors that restrict virus replication. METHODS. We assessed proviral DNA levels, autologous viral growth from and infectability of in vitro activated, CD8(+) T cell-depleted CD4(+) T cells from HIV elite controllers (mean viral load, <50 copies/mL), viremic controllers (mean viral load, <2000 copies/mL), chronic progressors, and individuals receiving highly active antiretroviral therapy. RESULTS. Although we successfully detected autologous virus production in ex vivo activated CD4(+) T cells from all chronic progressors and from most of the viremic controllers, we were able to measure robust autologous viral replication in only 2 of 14 elite controllers subjected to the same protocol. In vitro activated autologous CD4(+) T cells from elite controllers, however, supported infection with both X4 and R5 tropic HIV strains at comparable levels to those in CD4(+) T cells from HIV-uninfected subjects. Proviral DNA levels were the lowest in elite controllers, suggesting that extremely low frequencies of infected cells contribute to difficulty in isolation of virus. CONCLUSIONS. These data indicate that elite control is not due to inability of activated CD4(+) T cells to support HIV infection, but the relative contributions of host and viral factors that account for maintenance of low-level infection remain to be determined.

T cell receptor excision circles and HIV-1 2-LTR episomal DNA to predict AIDS in patients not receiving effective therapy

OBJECTIVE

To determine whether improved prediction of AIDS-free survival following HIV-1 seroconversion is achieved by measuring HIV-1 2-LTR episomal DNA (2-LTR) circles and T cell receptor rearrangement excision circles (TREC), reflecting HIV replication and lymphocyte emigration from the thymus, respectively.

DESIGN

Subanalysis of a cohort of 154 patients with hemophilia who became HIV positive between 1978 and 1985 and were followed prospectively.

METHODS

Relative hazards (RH) of AIDS, in the absence of highly effective anti-HIV therapy, were estimated for age, HIV-1 viral load, CD4 lymphocyte count and levels of HIV-1 2-LTR circles and TREC [per 106 peripheral blood mononuclear cells (PBMC)].

RESULTS

TREC correlated significantly with CD4 cell counts (r = 0.30) and age (r = -0.60). 2-LTR circles correlated significantly with HIV-1 viral load (r = 0.35). If viral load, CD4 lymphocytes and age were included in a proportional hazards model, the risk of AIDS during a median of 11.6 years of follow-up was increased significantly with fewer TREC (adjusted RH, 2.0 per log10 copies/106 PBMC) and more 2-LTR circles (RH, 1.7 per log10 copies/106 PBMC). AIDS prediction with TREC and 2-LTR circles held for most subgroups defined by median viral load, CD4 lymphocytes and age.

CONCLUSIONS

PBMC that have high levels of HIV-1 replication and low levels of recent thymic emigrants are associated with a substantially increased risk of AIDS. It is not known if measurement of either TREC or 2-LTR circles will complement HIV-1 viral load as an estimation of the risk of AIDS for patients who are receiving highly effective anti-HIV therapy.

Grossly defective nef gene sequences in a human immunodeficiency virus type 1-seropositive long-term nonprogressor

We have been investigating a long-term nonprogressor who was found to be human immunodeficiency virus type 1 (HIV-1) seropositive in 1985 and has survived with stable CD4+ T-cell counts (>1,000 CD4 cells/microl) without any AIDS-related illness. We have previously reported that repeated attempts to measure HIV-1 RNA in the peripheral mononuclear cells obtained from this subject have invariably failed. In the present study, we have analyzed the molecular nature of the HIV-1 quasispecies infecting this patient by PCR amplification of two proviral regions, the 5' long terminal repeat (5'LTR)/gag leader and the nef gene, directly from fresh uncultured peripheral mononuclear cells, followed by length polymorphism analysis (with 1994, 1995, and 1996 samples) and sequencing (with a 1996 sample). Only proviral forms with nef deletions were revealed by length polymorphism analysis in samples from all three time points. Sequence analysis of the nef gene from the 1996 sample confirmed the presence of similar proviral quasispecies characterized by the presence of several deletions located in the nef-alone and the nef/U3 overlapping regions. Length polymorphism analysis of the 5'LTR/gag leader region suggested the existence of two major quasispecies populations, one characterized by the presence of forms carrying deletions in the U3 region and the other showing a completely intact, full-length 5'LTR. Evidence of the role of nef gene defects in long-term survival of HIV-1-infected patients has been provided so far in two independent investigations involving patients infected with HIV through blood transfusion. Here we show the existence of a similar condition in a subject who acquired HIV-1 seropositivity through the sexual route.