Proportion of HIV-1 infected CD8+CD4- T lymphocytes in vivo.

The proportion and significance of HIV-1 infection of CD8+ T-cells was examined in a patient cohort of HIV-1 seropositive (n=28) and seronegative individuals (n=4). It was hypothesized that irrespective of the clinical status of the patients, productively HIV-1 infected CD8+ T-cells would be found and these cells would contribute to the plasma viral load in vivo. Flow cytometric analysis using fluorochrome-conjugated antibodies, RT-PCR analysis using HIV-1(pol) specific primers, and quantification of HIV-1 viral transcripts by ex vivo culture of isolated CD8+ T-cells were employed. In 22 of the 28 patient samples analyzed, a significantly higher proportion of cells with expression of CD8+HIV-1(gag)+ than of CD4+HIV-1(gag)+ T-cells was observed (36.9% +/- 10.0% vs 26.4% +/- 13.1% respectively, p< 0.01). No correlation was observed between absolute CD4 counts, CD8 counts, plasma viral load and CD8+ T cell infection. RT-PCR analysis indicated the presence of HIV-1 transcripts in the ex vivo isolated CD8+ T-cell population. Ex vivo isolated CD8+ T-cells demonstrated productive infection over time. We conclude, with three lines of evidence detecting and measuring HIV-1 infection of CD8+ T-lymphocytes, that this cellular target and reservoir may be central to HIV-1 pathogenesis.

Short communication: identification of a novel HIV type 1 subtype H/J recombinant in Canada with discordant HIV viral load (RNA) values in three different commercial assays.

The presence of HIV-1 non-B subtypes is increasing worldwide. This poses challenges to commercial diagnostic and viral load (RNA) monitoring tests that are predominantly based on HIV-1 subtype B strains. Based on phylogenetic analysis of the gag, pol, and env gene regions, we describe the first HIV-1 H/J recombinant in Canada that presented divergent viral load values. DNA sequence analysis of the gag gene region further revealed that genetic diversity between this H/J recombinant and the primers and probes used in the bio-Merieux Nuclisens HIV-1 QT (Nuclisens) and Roche Amplicor Monitor HIV-1, v1.5 (Monitor) viral RNA assays can erroneously lead to undetectable viral load values. This observation appears to be more problematic in the Nuclisens assay. In light of increasing genetic diversity in HIV worldwide we recommend that DNA sequencing of HIV, especially in the gag gene region targeted by primers and probes used in molecular diagnostic and viral load tests, be incorporated into clinical monitoring practices.

A combined HIV-1 protein bead array for serology assay and T-cell subset immunophenotyping with a hybrid flow cytometer: a step in the direction of a comprehensive multitasking instrument platform for infectious disease diagnosis and monitoring.

BACKGROUND: A new generation of bench-top flow cytometers with digital signal processing to perform suspension array technology (SAT) based bead array assays as well as leukocyte immunophenotyping is now available. These hybrid instruments provide an opportunity for the development of a more cost effective multitasking platform to support infectious disease treatment in resource limited countries. METHODS: We report the development and testing of two modules compatible with the hybrid flow cytometers. The first module is an eleven HIV-1 protein bead array (PBA) for the detection of circulating antibodies and the second is a cell based T-cell enumeration assay. RESULTS: The HIV-1 PBA was tested in parallel with two enzyme immunoassays (EIAs) for the detection of plasma antibodies from 4 HIV-1 seroconversion panels and a low antibody titer panel. The PBA as well as the two EIAs performed equally for the detection of antibody positive samples from all seroconversion panels. One antibody positive sample from the low antibody titer panel was missed by the PBA together with one of the two EIAs tested. A parallel analysis of the HIV-1 PBA with Western blot (a confirmatory test for HIV infection) using plasma from nine HIV-1(+) individuals showed that the HIV-1 PBA detected more of the gp41 and gp120 antibody positive samples. Preliminary CD4 T-cell immunophenotyping results from 14 HIV(+) and 10 HIV(-) whole blood specimens with the hybrid flow cytometer platform compared well to conventional flow cytometry data. CONCLUSION: The successful combination of bead and cell based assays on a single hybrid instrument demonstrated the potential utility of a multitasking platform. The results presented are providing groundwork for future development of more cost effective modular architecture for a flexible flow cytometry based platform.

Identification of mutations in proviral long terminal repeats of HIV type 1-infected subjects naive to drug therapy.

Human immunodeficiency virus type 1 (HIV-1) proviral DNA sequences in the 5' long terminal repeat (LTR) were examined among 28 drug-naive individuals. Twenty-four subjects had highly conserved LTR sequences, however, more significant changes were observed in the remaining four LTR sequences. These included a 9-bp deletion preceding the NF kappa B elements and a duplication of the RBF-2 motif. A higher overall frequency of mutations within the LTR occurred within NFAT-1 and Sp-1 sequences. Importantly, a novel 16-bp deletion was found in the distal NFAT-1 site.

Differential effects of interleukin-7 and interleukin-15 on NK cell anti-human immunodeficiency virus activity.

The ability of interleukin-7 (IL-7) and IL-15 to expand and/or augment effector cell functions may be of therapeutic benefit to human immunodeficiency virus (HIV)-infected patients. The functional effects of these cytokines on innate HIV-specific immunity and their impact on cells harboring HIV are unknown. We demonstrate that both IL-7 and IL-15 augment natural killer (NK) function by using cells (CD3(-) CD16(+) CD56(+)) from both HIV-positive and -negative donors. Whereas IL-7 enhances NK function through upregulation of Fas ligand, the effect of IL-15 is mediated through upregulation of tumor necrosis factor-related apoptosis-inducing ligand. The difference in these effector mechanisms is reflected by the ability of IL-15-treated but not IL-7-treated NK cells to reduce the burden of replication-competent HIV in autologous peripheral blood mononuclear cells (PBMC) (infectious units per million for control NK cells, 6.79; for IL-7-treated NK cells, 236.17; for IL-15-treated cells, 1.01; P = 0.01 versus control). In addition, the treatment of PBMC with IL-15-treated but not IL-7-treated NK cells causes undetectable HIV p24 (five of five cases), HIV RNA (five of five cases), or HIV DNA (three of five cases). These results support the concept of adjuvant immunotherapy of HIV infection with either IL-7 or IL-15 but suggest that the NK-mediated antiviral effect of IL-15 may be superior.

Vpr R77Q is associated with long-term nonprogressive HIV infection and impaired induction of apoptosis.

The absence of immune defects that occurs in the syndrome of long-term nonprogressive (LTNP) HIV infection offers insights into the pathophysiology of HIV-induced immune disease. The (H[F/S]RIG)(2) domain of viral protein R (Vpr) induces apoptosis and may contribute to HIV-induced T cell depletion. We demonstrate a higher frequency of R77Q Vpr mutations in patients with LTNP than in patients with progressive disease. In addition, T cell infections using vesicular stomatitis virus G (VSV-G) pseudotyped HIV-1 Vpr R77Q result in less (P = 0.01) T cell death than infections using wild-type Vpr, despite similar levels of viral replication. Wild-type Vpr-associated events, including procaspase-8 and -3 cleavage, loss of mitochondrial transmembrane potential (deltapsi(m)), and DNA fragmentation factor activation are attenuated by R77Q Vpr. These data highlight the pathophysiologic role of Vpr in HIV-induced immune disease and suggest a novel mechanism of LTNP.