[Show abstract][Hide abstract] ABSTRACT: Most T cell-based HIV-1 vaccine candidates induce responses of limited breadth for reasons that are unclear. We evaluated vaccine-induced T-cell responses in individuals receiving an HIV-1 recombinant adenoviral vaccine. Certain HLA alleles (B27, B57, B35, and B14) are preferentially utilized to mount HIV-specific responses, whereas other alleles (A02 and B07) are rarely utilized (P < 0.001). This preference seems due to 4 following factors individually or in combination: higher affinity of specific peptides to specific HLA alleles; higher avidity of T-cell receptor; HLA and peptide interaction; and/or higher surface expression of certain HLA. Thus, HLA immunodominance plays a substantial role in vaccine-induced T-cell responses.
Preview · Article · Jun 2011 · JAIDS Journal of Acquired Immune Deficiency Syndromes
[Show abstract][Hide abstract] ABSTRACT: HLA alleles B57/58, B27, and B35 have the strongest genetic associations with HIV-1 disease progression. The mechanisms of
these relationships may be host control of HIV-1 infection via CD8+ T-cell responses. We examined these immune responses in subjects from the Seattle Primary Infection Cohort with these alleles.
CD8+ T-cell responses to conserved HIV epitopes within B57/58 alleles (TW10 and KF11) and B27 alleles (KK10 and FY10) delayed
declines in CD4+ T-cell counts (4 to 8 times longer), while responses to variable epitopes presented by B35 alleles (DL9 and IL9) resulted
in more rapid progression. The plasma viral load was higher in B57/58+ and B27+ subjects lacking the conserved B57/58- and B27-restricted responses. The presence of certain B57/58-, B27-, and B35-restricted
HIV-specific CD8+ T-cell responses after primary HIV-1 infection better defined disease progression than the HLA genotype alone, suggesting
that it is the HIV-specific CD8+ T cells and not the presence of a particular HLA allele that determine disease progression. Further, the most effective host
CD8+ T-cell responses to HIV-1 were prevalent within an HLA allele, represented a high total allele fraction of the host CD8+ T-cell response, and targeted conserved regions of HIV-1. These data suggest that vaccine immunogens should contain only
conserved regions of HIV-1.
Full-text · Article · Feb 2010 · Journal of Virology
[Show abstract][Hide abstract] ABSTRACT: HIV-1-infected persons with HLA-B27 and -B57 alleles commonly remain healthy for decades without antiretroviral therapy. Properties of CD8+ T cells restricted by these alleles considered to confer disease protection in these individuals are elusive but important to understand and potentially elicit by vaccination. To address this, we compared CD8+ T cell function induced by HIV-1 immunogens and natural infection using polychromatic flow cytometry. HIV-1-specific CD8+ T cells from all four uninfected immunized and 21 infected subjects secreted IFN-gamma and TNF-alpha. However, CD8+ T cells induced by vaccination and primary infection, but not chronic infection, proliferated to their cognate epitopes. Notably, B27- and B57-restricted CD8+ T cells from nonprogressors exhibited greater expansion than those restricted by other alleles. Hence, CD8+ T cells restricted by certain protective alleles can resist replicative defects, which permits expansion and antiviral effector activities. Our findings suggest that the capacity to maintain CD8+ T cell proliferation, regardless of MHC-restriction, may serve as an important correlate of disease protection in the event of infection following vaccination.
Full-text · Article · Dec 2006 · The Journal of Immunology
[Show abstract][Hide abstract] ABSTRACT: Hepatitis C virus (HCV) F protein is encoded in an alternate reading frame overlapping the core protein region. Its precise sequence, biological function and mode of expression are currently unclear. This study was conducted to examine the prevalence and characteristics of host humoral and cell-mediated immune responses directed against F protein in patients co-infected with HCV and HIV-1.
Mutations were introduced to allow the expression of HCV-1a F protein in the absence of core. This recombinant and a truncated form lacking the first 11 amino acid residues shared with core were expressed in Escherichia coli, and their amino acid sequences were verified by mass spectrometry. Vaccinia-F protein recombinants were used to test F protein-specific cytotoxic T lymphocyte (CTL) activity. The binding of F protein-derived peptides to HLA-A*0201 was studied to identify putative CTL epitopes.
Sera from 23 of 39 patients infected with various HCV genotypes recognized the truncated form, including 13 of 25 subjects co-infected with HIV-1, indicative of antigenic crossreactivity and consistent with the conservation of F protein coding sequences between HCV genotypes. Crossreactive F protein-specific CTL precursors were detected in nine of 11 HCV-infected subjects, including seven of nine patients co-infected with HCV and HIV-1. Finally, three novel putative HLA-A*0201-restricted CTL epitopes were identified.
These results indicate that patients co-infected with HCV and HIV-1 can mount immunoglobulin and CTL responses directed against HCV F protein that are fully comparable in scope and magnitude with those observed in individuals infected with HCV alone.