Cytotoxic T lymphocyte escape variants, induced mutations, and synthetic peptides define a dominant H-2Kb-restricted determinant in simian virus 40 tumor antigen.
Immunization of C57BL/6 mice with syngeneic cells transformed by simian virus 40 large T antigen (SV40 T ag) induces the generation of T antigen-specific cytotoxic T lymphocytes (CTL) which are restricted by the major histocompatibility class I antigens H-2Db and H-2Kb. Previous studies have shown that the H-2Db-restricted CTL response is directed to at least three distinct epitopes (I, II/III, and V) in the SV40 T antigen which have been precisely mapped using deletion mutagenesis and overlapping synthetic peptides. Although in vivo the CTL response to SV40 T antigen is dominated by the H-2Kb class I antigen, the precise location of the H-2Kb-restricted epitope(s) was not known, and whether there was multiplicity of H-2Kb-restricted epitopes remained unclear. In this study, we have defined the minimal recognition epitope for the SV40-specific H-2Kb-restricted CTL clone Y-4 as T antigen residues 404-411 by using T antigen deletion and point mutants and synthetic peptides. DNA sequence analysis of the region encoding residues 404-411 from the T antigens expressed in three independently isolated CTL clone Y-4 escape variants identified inactivating mutations capable of abrogating CTL recognition. Estimation of CTL precursor (CTLp) frequencies by limiting dilution analysis revealed that CTLp specific for epitope IV represent a large percentage of the total CTL response elicited by the intact T antigen in H-2b mice. Immunization of B6 mice with cells expressing a T antigen derivative deleted of residues 404-411 revealed that site IV represents the only immunodominant H-2Kb-restricted epitope within T antigen.
Mylin
L M
LM
Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey 17033, USA.
Deckhut
A M
AM
Bonneau
R H
RH
Kierstead
T D
TD
Tevethia
M J
MJ
Simmons
D T
DT
Tevethi
S S
SS
D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics* / Q000276:immunology; D002460:Cell Line; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D006183:H-2 Antigens / Q000235:genetics* / Q000276:immunology; D016056:Immunodominant Epitopes / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D027601:Polyomavirus Infections / Q000235:genetics / Q000276:immunology*; D013539:Simian virus 40 / Q000235:genetics / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000821:virology*; D014412:Tumor Virus Infections / Q000235:genetics / Q000276:immunology*
D000952:Antigens, Polyomavirus Transforming; D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D016056:Immunodominant Epitopes