Naturally processed viral peptides recognized by cytotoxic T lymphocytes on cells chronically infected by human immunodeficiency virus type 1.
We have established long-term cultures of several cell lines stably and uniformly expressing human immunodeficiency virus type 1 (HIV-1) in order to (a) identify naturally processed HIV-1 peptides recognized by cytotoxic T lymphocytes (CTL) from HIV-1-seropositive individuals and (b) consider the hypothesis that naturally occurring epitope densities on HIV-infected cells may limit their lysis by CTL. Each of two A2-restricted CD8+ CTL specific for HIV-1 gag or reverse transcriptase (RT) recognized a single naturally processed HIV-1 peptide in trifluoroacetic acid (TFA) extracts of infected cells: gag 77-85 (SLYNTVATL) or RT 476-484 (ILKEPVHGV). Both processed peptides match the synthetic peptides that are optimally active in cytotoxicity assays and have the consensus motif described for A2-associated peptides. Their abundances were approximately 400 and approximately 12 molecules per infected Jurkat-A2 cell, respectively. Other synthetic HIV-1 peptides active at subnanomolar concentrations were not present in infected cells. Except for the antigen processing mutant line T2, HIV-infected HLA-A2+ cell lines were specifically lysed by both A2-restricted CTL, although infected Jurkat-A2 cells were lysed more poorly by RT-specific CTL than by gag-specific CTL, suggesting that low cell surface density of a natural peptide may limit the effectiveness of some HIV-specific CTL despite their vigorous activity against synthetic peptide-treated target cells.
Tsomides
T J
TJ
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
Aldovini
A
A
Johnson
R P
RP
Walker
B D
BD
Young
R A
RA
Eisen
H N
HN
D000595:Amino Acid Sequence; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D015683:Gene Products, gag / Q000276:immunology*; D054303:HIV Reverse Transcriptase; D015497:HIV-1 / Q000276:immunology*; D015789:HLA-A2 Antigen / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D012194:RNA-Directed DNA Polymerase / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D015683:Gene Products, gag; D015789:HLA-A2 Antigen; D010446:Peptide Fragments; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase