7th International AIDS Conference Florence, Italy — June 16-21, 1991

Int Conf AIDS 1991 Jun 16-21; 7:95 (abstract no. M.A.1015)
Meneveri R, Grassi F, Marozzi A, Agresti A, Siccardi A, Ginelli E; Dipartimento Biologia e Genetica per li Scienze Mediche, Universita di Milano, Italy

OBJECTIVE: To characterize a 45 kD human protein which shares an epitope with HIV-1 gp120. The protein, present at high concentrations on the surface of activated immunocytes, is defined by two Mabs (M38 and L31) one of which (M38) is cross-reactive with the virus.

METHODS: Immunoscreening of an expression cDNA library from human activated lymphocytes. Sequencing of an isolated recombinant clone. Data bank analysis of derived nucleotide and amino acid sequences. Immunoprecipitation and Western-blot analysis.

RESULTS: A clone, producing a L31- and M38-positive recombinant protein, has been isolated. The insert sequence (1549 bp) contains an ORF coding for a protein of 366 aa which is highly homologous (96%) with the allele Cb-1 of the HLA Class I multigene family. Furthermore, immunoprecipitation experiments indicate that the epitopes defined by Mabs L31 and M38 are common and monomorphic determinants of HLA Class I heavy chain.

DISCUSSION AND CONCLUSIONS: HIV-1 gp120 shares an epitope with HLA Class I heavy chain. Moreover, by comparing the expression patterns of L31/M38-defined epitopes and of classical HLA antigens, it can be suggested that L31/M38 determinants reside on structurally altered HLA molecules present on the cell surface upon cell activation.

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