| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1994: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Several cytotoxic T-lymphocyte (CTL) epitopes have been defined in hepatitis C virus (HCV) proteins. CTL may play an important role in the control of infection by HCV.Here, we identify a highly conserved antigenic site in the HCV core recognized by both murine and human CTL.Spleen cells from mice immunized with a recombinant vaccinia virus expressing the HCV core gene were restimulated in vitro with 11 peptides from the core protein. CTL from H-2^d mice responded to a single 16-residue synthetic peptide (HCV 129-144). This conserved epitope was presented by a murine class I major histocompatibility molecule (H-2D^d) to conventional CD4^- CD8^+ CTL mapped by using transfectants expressing D^d, L^d, or K^d, but was not seen by CTL restricted by H-2^b. The murine epitope was mapped to the decapeptide LMGYIPLVGA.The same 16-residue peptide was recognized by CTL from two HCV-seropositive patients but not by CTL from any scronegative donors. CTL from two HLA-A2-positive patients with acute a
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nd chronic hepatitides C recognized a 9-residue fragment (DLMGYIPLV) of the peptide presented by HLA-A2 and containing an HLA-A2-binding motif, extending only 1 residue beyond the murine epitope. Therefore, this conserved peptide, seen with murine CTL and human CTL with a very prevalent HLA class I molecule, may be a valuable component of an HCV vaccine against a broad range of HCV isolates. This study demonstrates that the screening for CTL epitopes in mice prior to human study may be useful.
Vaccine development in animal models depends on ability to recognize epitopes seen by human T cells. In this work, we show that CTL responses in transgenic mice expressing human HLA-A2.1 prospectively predict the same four of 11 hepatitis C virus (HCV) structural protein-derived peptides, expressing a sequence motif for HLA-A2.1 binding, that are actually recognized by human A2.1-restricted CTLs. The CTLs also recognized targets endogenously expressing these proteins. Human CTLs from HCV-infected patients, tested by using the same peptides, revealed a virtually identical response repertoire. A highly conserved HCV core peptide was the most immunogenic, and may-be a valuable component of a vaccine against a broad range of HCV isolates in HLA-A2-positive patients. These results suggest that, in spite of species differences, the T cell repertoire is plastic enough to allow a similar response when the same class I MHC molecule is presenting the peptide. Thus, the HLA molecule plays the primary role in determining which peptides are recognized by CTLs. This transgenic mouse model is important for the study of HLA-restricted CTL determinants and for an approach to design a potential HCV vaccine. Less
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