Jd. Lippolis et al., FUNCTIONAL-ANALYSIS OF AMINO-ACID-RESIDUES ENCOMPASSING AND SURROUNDING 2 NEIGHBORING H-2D(B)-RESTRICTED CYTOTOXIC T-LYMPHOCYTE EPITOPES INSIMIAN-VIRUS-40 TUMOR-ANTIGEN, Journal of virology, 69(5), 1995, pp. 3134-3146
Simian virus 40 tumor (T) antigen contains three H-2D(b)- and one H-2K
(b)-restricted cytotoxic T. lymphocyte (CTL) epitopes (sites). Two of
the H-2D(b)-restricted CTL epitopes, I and II/III, are separated by 7
amino acids in the amino-terminal one third of T antigen. In this stud
y, we determine if the amino acids separating these two H-2D(b) restri
cted CTL epitopes are dispensable for efficient processing and present
ation. In addition, the importance of amino acid residues lying within
and flanking the H-2D(b)-restricted epitopes I and II/III for efficie
nt processing, presentation, and recognition by site-specific CTL clon
es was determined by using T-antigen mutants containing single-amino-a
cid substitutions between residues 200 and 239. Using synthetic peptid
es in CTL lysis and major histocompatibility complex class I stabiliza
tion assays, CTL recognition site I has been redefined to include resi
dues 206 to 215. Substitutions in amino acids flanking either site I o
r site II/III did not affect recognition by any of the T-antigen-speci
fic CTL clones. Additionally, the removal of the 7 residues separating
site I and site II/III did not affect CTL recognition, thus demonstra
ting that these two epitopes when arranged in tandem in the native T a
ntigen can be efficiently processed and presented to CTL clones. Diffe
rences in fine specificities of two CTL clones which recognize the sam
e epitope (Y-1 and K-11 for site I and Y-2 and Y-3 for site II/III) ha
ve been used in conjunction with synthetic peptide variants to assign
roles for residues within epitopes I and II/III with respect to TCR re
cognition and/or peptide major histocompatibility complex association.