Immunogenicity of two peptide determinants in the cytolytic T-cell response to flavivirus infection: inverse correlation between peptide affinity for MHC class I and T-cell precursor frequency.
We used the CD8+ cytotoxic T (Tc) cell immune response against the flavivirus, Murray Valley encephalitis virus (MVE), restricted by the H-2Kk major histocompatibility complex (MHC) class I molecule, to investigate immunodominance. Split-clone limiting dilution analysis revealed almost exclusive recognition of two peptides, MVE1785 and MVE1971, derived from the viral NS3 protein. The precursor frequency of MVE-reactive Tc cells was determined by limiting dilution analysis for cytotoxic function and intracellular staining for interferon-gamma; the latter gave a 100-fold higher estimate of MVE-reactive Tc cell precursors. MHC class I cell surface stabilization assays revealed that affinity for H-2Kk as well as halflives of the peptide-H-2Kk-complexes were markedly different for the two peptides. However, a kinetic study of antigen presentation showed that both peptides are presented for recognition by Tc cells with a comparable kinetics during the latent period of virus infection. Nevertheless, the lower affinity peptide MVE1785 elicited roughly twofold more Tc cell clones than the high-affinity peptide MVE1971. While the cytolytic activity against both determinants was similar after in vitro restimulation at the peak of the primary response, the smaller pool of memory anti-MVE1971 Tc cells correlated with an impaired memory response against that determinant, suggesting that the available T-cell repertoire is a major factor influencing the establishment of T-cell memory.
Regner
M
M
Division of Immunology and Cell Biology, John Curtin School of Medical Research, Australian National University, Canberra, ACT.
Müllbacher
A
A
Blanden
R V
RV
Lobigs
M
M
D000818:Animals; D004306:Dose-Response Relationship, Immunologic; D018068:Encephalitis Virus, Murray Valley / Q000276:immunology*; D005260:Female; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis; D051379:Mice; D008808:Mice, Inbred CBA; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014764:Viral Proteins / Q000276:immunology* / Q000378:metabolism
D015395:Histocompatibility Antigens Class I; D014764:Viral Proteins; D007371:Interferon-gamma