TPCK inhibits AGC kinases by direct activation loop adduction at phenylalanine-directed cysteine residues.

N-alpha-tosyl-L-phenylalanyl chloromethyl ketone (TPCK) has anti-tumorigenic properties, but its direct cellular targets are unknown. Previously, we showed TPCK inhibited the PDKl-dependent AGC kinases RSK, Akt and S6K1 without inhibiting PKA, ERK1/2, PI3K, and PDK1 itself. Here we show TPCK-inhibition of the RSK-related kinases MSK1 and 2, which can be activated independently of PDK1.

Extensive HLA class I allele promiscuity among viral CTL epitopes.

Promiscuous binding of T helper epitopes to MHC class II molecules has been well established, but few examples of promiscuous class I-restricted epitopes exist. To address the extent of promiscuity of HLA class I peptides, responses to 242 well-defined viral epitopes were tested in 100 subjects regardless of the individuals' HLA type. Surprisingly, half of all detected responses were seen in the absence of the originally reported restricting HLA class I allele, and only 3% of epitopes were recognized exclusively in the presence of their original allele.

Impact of HLA-B alleles, epitope binding affinity, functional avidity, and viral coinfection on the immunodominance of virus-specific CTL responses.

Immunodominance is variably used to describe either the most frequently detectable response among tested individuals or the strongest response within a single individual, yet factors determining either inter- or intraindividual immunodominance are still poorly understood. More than 90 individuals were tested against 184 HIV- and 92 EBV-derived, previously defined CTL epitopes. The data show that HLA-B-restricted epitopes were significantly more frequently recognized than HLA-A- or HLA-C-restricted epitopes.

Longitudinal analysis of clinical markers following antiretroviral therapy initiated during acute or early HIV type 1 infection.

Background: Treatment of acute human immunodeficiency virus type 1 (HIV-1) infection may have unique immunologic, virological, and clinical benefits. However, the timing of treatment, optimal starting regimens, and expected response to therapy have not been defined.Methods.

Control of human immunodeficiency virus replication by cytotoxic T lymphocytes targeting subdominant epitopes.

Despite limited data supporting the superiority of dominant over subdominant responses, immunodominant epitopes represent the preferred vaccine candidates. To address the function of subdominant responses in human immunodeficiency virus infection, we analyzed cytotoxic T lymphocyte responses restricted by HLA-B*1503, a rare allele in a cohort infected with clade B, although common in one infected with clade C. HLA-B*1503 was associated with reduced viral loads in the clade B cohort but not the clade C cohort, although both shared the immunodominant response.

HLA-B63 presents HLA-B57/B58-restricted cytotoxic T-lymphocyte epitopes and is associated with low human immunodeficiency virus load.

Several HLA class I alleles have been associated with slow human immunodeficiency virus (HIV) disease progression, supporting the important role HLA class I-restricted cytotoxic T lymphocytes (CTL) play in controlling HIV infection. HLA-B63, the serological marker for the closely related HLA-B*1516 and HLA-B*1517 alleles, shares the epitope binding motif of HLA-B57 and HLA-B58, two alleles that have been associated with slow HIV disease progression. We investigated whether HIV-infected individuals who express HLA-B63 generate CTL responses that are comparable in breadth and specificity to those of HLA-B57/58-positive subjects and whether HLA-B63-positive individuals would also present with lower viral set points than the general population.

Loss of HIV-1-specific CD8+ T cell proliferation after acute HIV-1 infection and restoration by vaccine-induced HIV-1-specific CD4+ T cells.

Virus-specific CD8(+) T cells are associated with declining viremia in acute human immunodeficiency virus (HIV)1 infection, but do not correlate with control of viremia in chronic infection, suggesting a progressive functional defect not measured by interferon gamma assays presently used. Here, we demonstrate that HIV-1-specific CD8(+) T cells proliferate rapidly upon encounter with cognate antigen in acute infection, but lose this capacity with ongoing viral replication. This functional defect can be induced in vitro by depletion of CD4(+) T cells or addition of interleukin 2-neutralizing antibodies, and can be corrected in chronic infection in vitro by addition of autologous CD4(+) T cells isolated during acute infection and in vivo by vaccine-mediated induction of HIV-1-specific CD4(+) T helper cell responses.

HIV-1 Nef is preferentially recognized by CD8 T cells in primary HIV-1 infection despite a relatively high degree of genetic diversity.

Objective: To compare the magnitude, breadth and protein specificity of HIV-1-specific CD8 T-cell responses against the clade B consensus sequence during primary and chronic HIV-1 infection and to analyze the impact of viral diversity on the localization of detected responses.

Methods: HIV-1-specific CD8 T-cell responses against the clade B consensus sequence in individuals with acute (n = 10), early (n = 19) and chronic (n = 10) infection were longitudinally assessed using an interferon-gamma EliSpot assay.

Results: CD8 T-cell responses against clade B consensus sequences were preferentially directed against central regions of Nef during primary HIV-1 infection, despite a relatively higher degree of genetic diversity compared with other subsequently targeted regions.

HIV-1-specific cytotoxicity is preferentially mediated by a subset of CD8(+) T cells producing both interferon-gamma and tumor necrosis factor-alpha.

CD8(+) T cells play a crucial role in the control of viral infections by direct elimination of infected cells and secretion of a number of soluble factors. Recent data suggest that HIV-1-specific CD8(+) T cell subsets may differ in their ability to exert these effector functions. Here, we directly compared the cytokine secretion patterns and cytotoxic capacity of HIV-1-specific CD8(+) T cells, using a flow-cytometric cytotoxicity assay based on caspase-3 activation in dying target cells.