Cohort Of Long-term Nonprogressors Research Articles

Antibody Responses to HIV-1 gp120 Hypervariable Regions in Six Long-Term Non-Progressors

Our long-term goal is to discover the combination of host parameters that help some HIV-infected individuals to resist progression to AIDS. In this study, we examined antibody responses using multiple samples obtained from a cohort of Long-Term Non-Progressors (LTNPs). Our hypothesis is that antibody responses to variable regions of the HIV-1 envelope glycoprotein are involved in reducing the viral load associated with LTNPs and that these specific immune responses influence susceptibility to disease progression. Multiple plasma samples were obtained from patients identified as LTNPs with the objective of characterizing humoral immune response directed to the five hypervariable regions of the envelope glycoprotein. Antibody binding was tested against peptides representing the five hypervariable regions of gp120, as well as against analog peptides representing different isolates of HIV-1 and against recombinant envelope glycoprotein. LTNPs have specific antibodies to the hypervariable regions of the envelope glycoprotein and develop different patterns of antibody recognition to variable epitopes of envelope glycoprotein. These antibodies can be detected using HIV peptides as capture antigens.

Can HIV Be Cured and Should We Try?

An estimated 35.0 million persons live with HIV; 2.1 million new infections occurred and 1.5 million persons died of HIV in 2013 (World Health Organization, http://www.who.int/hiv/data/epi_core_dec2014.png?ua=1). Despite effective combination antiretroviral therapy (cART), less than one-quarter of patients can access these life-prolonging medications; and despite its effectiveness, cART does not normalize life expectancy, as premature aging, metabolic complications and chronic inflammation complicate HIV therapy. HIV is incurable due to the presence of a latent viral reservoir. During the life cycle of the virus, HIV integrates into the host DNA. A subset of integrated HIV provirus remains transcriptionally silent, producing neither viral proteins nor viral progeny, until reactivation by various physiologic stimuli. This latency of HIV allows some infected cells to escape immune detection and elimination, and these latently infected cells constitute the viral reservoir. The latent viral reservoir allows viral rebound within weeks of interruption of cART, 1,2 where the magnitude of viral replication approaches that present pre-therapy. Although it was once thought that viral rebound occurred universally following therapy interruption, several recent reports challenge that paradigm. The “Berlin patient” successfully cleared HIV after two allogeneic transplants from a donor with homozygous CCR5Δ32 mutation,3 and he has not rebounded HIV after nearly seven years. This case likely represents a cure from HIV; yet other cases have been described where HIV rebound has been attenuated, or delayed. The “Mississippi” baby was a perinatally HIV-infected infant who initiated cART within hours of birth, and when interrupted eighteen months later, viremia remained undetectable for nearly two years.4 The Harvard BMT cases underwent allogeneic BMT, developed undetectable HIV DNA, yet rebounded viremia within only eight months after cART discontinuation.5 Together these cases demonstrate that control of viremia in the absence of cART is possible, if not durable.4 The VISCONTI cohort of 14 HIV-infected adults who initiated antiretroviral therapy during acute infection, and in whom high level rebound viremia had not occurred several years after cessation of therapy,6 similarly demonstrated that viral rebound following cART interruption can be attenuated. These cases have reinvigorated research toward finding a cure for HIV, which certainly will require an exceptional investment of time, talent and resources. Thus it is prudent to question whether such resources would be better devoted to more proximate needs with proven results (such as supplying cART to those without access to it, or supplying pre/post exposure prophylaxis to reduce the rate of new infections).

Characterization of rare lens epithelium-derived growth factor/p75 genetic variants identified in HIV-1 long-term nonprogressors

Lens epithelium-derived growth factor (LEDGF)/p75 is a cellular binding partner of HIV-1 integrase and a crucial cofactor for HIV-1 replication. Here, we study two LEDGF/p75 exonic variants I436S and T473I, identified in HIV-1 long-term nonprogressors, together with Q472L. In-vitro binding assays, cell culture complementation, and functional rescue. Binding affinities of wild-type, I436S, T473I, and Q472L LEDGF/p75 for HIV-1 integrase were comparable. All LEDGF/p75 variants bound equally well to LEDGF/p75 interacting partners JPO2 and PogZ. In addition, HIV-1 replication was evaluated in human somatic LEDGF/p75-knockout cells and LEDGF/p75-knockdown cells complemented with either wild-type LEDGF/p75 or the respective LEDGF/p75 variants. All variants rescued HIV-1 replication to wild-type levels, whereas LEDGF/p75 D366N, defective for interaction with HIV-1 integrase, did not. Although identified in a cohort of long-term nonprogressors, our study did not indicate that the I436S or T473I mutation in LEDGF/p75 affects the interaction with HIV-1 integrase.

Clinicoimmunological Progression and Response to Treatment of Long-Term Nonprogressor HIV–Hepatitis C Virus-Coinfected Patients

We assess the severity and response to treatment of hepatitis C virus (HCV) infection in a cohort of long-term nonprogressors (LTNP) and analyze whether HCV infection affects the progression of HIV-1 infection. A case-control study comparing coinfected LTNP (n = 28) with coinfected normal progressors (NP) (n = 56) was performed. Signs of hepatopathy, response to HCV treatment, HIV viral load (VL), and lymphocyte T subsets were analyzed. A cohort of LTNP with (n = 28) and without HCV infection (n = 7) was compared to assess the influence of HCV on HIV-1 infection. Liver enzymes were lower in LTNP than in NP. There were no significant differences between LTNP and NP in clinical signs of chronic liver disease at physical examination, echostructure, degree of inflammation, or fibrosis score in liver biopsy. There were no differences in the response to HCV treatment between groups (57% vs. 45%, p = 0.69). LTNP presented a proportionally higher drop of CD4 during HCV treatment, which persisted 2 years after discontinuing treatment [-195, -10, and 30 cells/mm3 HCV-treated LTNP (n = 7), NP (n = 56), and non-HCV-treated LTNP (n = 21), respectively, p < 0.05]. There were no differences in any variables analyzed when coinfected and monoinfected LTNP were compared. LTNP do not seem to have a better outcome or response to HCV treatment than NP. HCV-treated LTNP could have a worse HIV progression than HIV-HCV-treated NP or untreated coinfected LTNP. HCV infection does not have a deleterious effect on the progression of LTNP.

Hepatitis C virus (HCV) coinfection in a cohort of HIV positive long-term non-progressors: Possible protective effect of infecting HCV genotype on HIV disease progression

Background and objective Hepatitis C virus (HCV) infection is frequent in HIV-positive subjects. We evaluated the potential impact of HCV coinfection and other determinants on HIV disease progression in a cohort of long-term non-progressors (LTNPs). Study design We studied immunological and virological factors in a cohort of 49 LTNPs, 23 of whom progressed during the follow-up (late progressors; LPs). Results HCV coinfection was detected in 19/26 LTNPs and 15/23 LPs. Univariate analysis showed that HIV viral load was associated with disease progression ( P = 0.04), and time-to-event analysis indicated that HCV genotype 1 significantly correlated with LTNP status ( P = 0.031). At multivariate analysis, HIV viremia at study entry remained independently associated with LTNP status ( P = 0.049). When the most represented genotypes (1 and 3a) were considered in the model, genotype 3a infection ( P = 0.034) and gender ( P = 0.035) emerged as independent variables related to HIV disease progression, whereas HIV viral load disappeared. Conclusions In addition to HIV viremia, coinfection with different HCV genotypes and gender may affect LTNP status.

Differences in disease progression in a cohort of long-term non-progressors after more than 16 years of HIV-1 infection.

It is unclear whether resistance to immunologic damage in long-term non-progressors (LTNP) will last indefinitely or whether it merely represents the extreme of a Gaussian distribution, and therefore progression will occur eventually. A cohort of 19 LTNP was established in 1997. Plasma viraemia and CD4 cell counts were measured two to three times each year until 2003. Analyses of nef and vpr viral genes, CCR5 genotypes, co-receptor tropism, viral replication capacity, and immunological parameters were performed. Twelve subjects (non-progressors, NP) showed stable CD4 cell counts over the 6-year follow-up, while seven (slow progressors, SP) showed a trend towards progressive CD4 cell depletion; however, only three SP experienced significant CD4 cell count declines. All SP had detectable plasma HIV-RNA (median 1118 copies/ml). In contrast, five of 12 NP had always undetectable viraemia. Only one patient showed a deletion in nef. The vpr R77Q change was recognized in seven patients. All patients were infected with R5 viruses. The virus replicative capacity was reduced in all tested individuals (range 5-93%). None of the patients was homozygous for the delta-32 CCR5 genotype, which was found in heterozygosis in three. CD8 T-cell activation was low in all but three individuals, all of whom had detectable viraemia and showed progressive CD4 cell depletion. Cytotoxic T lymphocyte responses were similar to those found in a control group of HIV progressors. A substantial proportion of LTNP show low-level virus replication and progressive loss of CD4 T cells over time. Progressive immunologic damage seems to be directly associated with some degree of virus replication and T-cell activation.

Frequency and function of HIV-specific CD8 + T Cells

The virus-specific CD8 + T cell responses of 27 HIV-infected patients were studied, including a unique cohort of long term nonprogressors (LTNP) with normal CD4 + T cell counts, low levels of plasma viral RNA, strong proliferative responses to HIV antigens and an over-representation of the HLA B*5701 class I allele. The frequencies of CD8 + T cells specific to the majority of HIV gene products were measured by flow cytometric detection of intracellular interferon-gamma (IFN-γ) in response to HIV-vaccinia recombinant infected autologous B cells. Very high frequencies (1.4–22%) of circulating CD8 + T cells were found to be HIV-specific and were not only found in LTNP with reduced plasma virus. No correlation was evident between the frequency of HIV-specific CD8 + T cells and levels of plasma viremia. In each case, the vast majority of cells (up to 17.2%) responded to Gag– Pol gene products. Although similar frequencies of Gag peptide-specific CD8 + T cells were found in LTNP and progressors by either intracellular IFN-γ or MHC class I tetramer staining, the breadth of these responses was greater in patients with progressive HIV infection compared with the LTNP group. The frequency of CD8 + T cells specific for a single peptide was not representative of an individual patient's total HIV-specific CD8 + T cell response. These data demonstrate that high numbers of HIV-specific CD8 + T cells exist even in patients with high level viremia and progressive disease. Further, they suggest that other qualitative parameters of the CD8 + T cell response may differentiate some patients with very low levels of plasma virus and nonprogressive infection.

Attenuated and wild-type HIV-1 infections and long terminal repeat-mediated gene expression from plasmids delivered by gene gun to human skin ex vivo and macaques in vivo.

Gene expression from HIV-based gene therapy vectors or live-attenuated HIV-1 vaccines requires RNA transcription supported by the HIV-1 promoter, the long terminal repeat (LTR). Delivery of live-attenuated HIV-1 vaccines as plasmid DNA would overcome problems associated with production of attenuated HIV-1 strains. We investigated the expression of reporter plasmids and proviral HIV-1 constructs driven by either the HIV-1 LTR or LTRs with deletions in the U3 enhancer regions. LTR-driven plasmids were inoculated by gene gun into both human epidermis ex vivo and macaques in vivo. The HIV-1 LTR drove reporter gene expression in human and macaque skin, although with 15- to 20-fold less efficiency compared to the immediate-early cytomegalovirus promoter. A deleted LTR derived from a naturally attenuated HIV-1 strain infecting a member of the well-characterized Sydney Blood Bank Cohort of long-term nonprogressors was 5-fold less efficient in expression of the reporter gene compared to wild-type LTR. Delivery of proviral wild-type HIV-1 DNA constructs to human skin resulted in recovery of HIV-1 from cells emigrating from the epidermis, providing an ex vivo model of the infectivity of proviral HIV-1 DNA. However, delivery of proviral HIV-1 DNA containing deletions in either the LTR, Nef, or the secondary viral transcription activator,Vpr, significantly reduced HIV-1 replication in this model. The early coexpression of Tat from a second plasmid did not restore replication. Thus, although attenuated lentiviral vaccines might be deliverable as proviral DNA constructs in primate subjects, significant improvements are needed to enhance the efficiency of this method.