title: Amino-terminal alteration of the HLA-A*0201-restricted human immunodeficiency virus pol peptide increases complex stability and in vitro immunogenicity.
abstract: Initial studies suggested that major histocompatibility complex class I-restricted viral epitopes could be predicted by the presence of particular residues termed anchors. However, recent studies showed that nonanchor positions of the epitopes are also significant for class I binding and recognition by cytotoxic T lymphocytes (CTLs). We investigated if changing nonanchor amino acids could increase class I affinity, complex stability, and T-cell recognition of a natural viral epitope. This concept was tested by using the HLA-A 0201-restricted human immunodeficiency virus type 1 epitope from reverse transcriptase (pol). Position 1 (P1) amino acid substitutions were emphasized because P1 alterations may not alter the T-cell receptor interaction. The peptide with the P1 substitution of tyrosine for isoleucine (I1Y) showed a binding affinity for HLA-A 0201 similar to that of the wild-type pol peptide in a cell lysate assembly assay. Surprisingly, I1Y significantly increased the HLA-A 0201-peptide complex stability at the cell surface. I1Y sensitized HLA-A 0201-expressing target cells for wild-type pol-specific CTL lysis as well as wild-type pol. Peripheral blood lymphocytes from three HLA-A2 HIV-seropositive individuals were stimulated in vitro with I1Y and wild-type pol. I1Y stimulated a higher wild-type pol-specific CTL response than wild-type pol in all three donors. Thus, I1Y may be an "improved" epitope for use as a CTL-based human immunodeficiency virus vaccine component. The design of improved epitopes has important ramifications for prophylaxis and therapeutic vaccine development.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina, Chapel Hill 27599, USA.
authors.forename: R R
authors.initials: RR
authors.lastname: Pogue
authors.forename: J
authors.initials: J
authors.lastname: Eron
authors.forename: J A
authors.initials: JA
authors.lastname: Frelinger
authors.forename: M
authors.initials: M
authors.lastname: Matsui
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D000939:Epitopes / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D015684:Gene Products, pol / Q000235:genetics / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D015234:HLA-A Antigens / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D017931:DNA Primers; D000939:Epitopes; D015684:Gene Products, pol; D015234:HLA-A Antigens