AEGiS-11IAC: Peptide-binding motif analysis of HLA class I from an HIV-resistant prostitute.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Peptide-binding motif analysis of HLA class I from an HIV-resistant prostitute.

Int Conf AIDS 1996 Jul 7-12; 11:212 (abstract no. Th.A.146)
Luscher MA, Bwayo J, Ball B, Plummer F, MacDonald KS, Barber BH; Dept. Immunology, University of Toronto, Toronto, ON, Canada. Fax: (416) 978-1938. E-mail: luscher@immune.med.utoronto.ca.

OBJECTIVE: To understand the mechanism of naturally-arising HIV resistance, which is observed with a frequency of about 5 percent in the prostitute cohort of the Nairobi Sex Worker's study. To better understand the role of the major histocompatibility complex (MHC) class I molecule in HIV resistance, since MHC rarity and certain serologically defined MHC phenotypes correlate with resistance. To determine the peptide-binding motif of an MHC class I molecule derived from an HIV-resistant prostitute.

METHODS: Peripheral blood lymphocytes from HIV-resistant prostitutes were transformed in vitro using Epstein-Barr virus. The cells of one woman, found to be homozygous at the HLA-A locus by direct nucleotide sequencing, expressed the protein product of A*0214. Large numbers of these cells (approximately 5x109) were grown in hollow-fibre cultures, and detergent lysates were prepared. Class I molecules were purified by affinity HPLC from the lysates and were dissociated by treatment with acetic acid. Small peptides were separated from antibody and class I subunits by ultrafiltration and were further purified by reversed-phase HPLC. This peptide fraction was pool-sequenced by Edman degradation. The sequence data were examined for prominent residues which increased in relative quantity by more than a factor of two between one degradative cycle and the next. Such residues were scored as motif' residues, and are candidate anchors for peptide binding to A*0214.

RESULTS: At the second cycle of the sequencing reaction, valine and glutamine together contributed over 30 percent of the amino acid content of the pooled peptides. Lysine was present at over 20 percent of the total (compared to a 5 percent background) at position 6, and the combination of valine and leucine at position 9 was over 20 percent. Other sub-dominant amino acids included arginine (16 percent) at position 3, and proline (15 percent) at position 5.

CONCLUSIONS: The data suggest a peptide binding motif for the prostitute-derived class I molecule HLA-A *0214, namely X-(VQ)-r-X-p-K-X-X-(VL). Using this motif information, candidate optimal length synthetic peptides derived from the sequence of HIV gene products can now be assessed as potential targets for cytotoxic T-lymphocytes from A*0214-expressing resistant women. The role of the cytotoxic T cell in the resistance phenotype should become more clear as cytotoxic responses in such women are analyzed at the level of individual peptide epitopes.

Keywords: AEGIS, HLA Antigens, HIV, Peptides, Prostitution, T-Lymphocytes, Cytotoxic, Epitopes, HIV-1, HIV Envelope Protein gp120, HIV Infections, Kenya, Human, Female, In Vitro, analysis, pharmacokinetics, ICA11

960707
ThA146