Epitope location of 13 anti-gag HIV-1 monoclonal antibodies using oligopeptides and their cross reactivity with HIV-2

Abstract

A series of 15-mer oligopeptides which overlapped by five amino acids (AA) across the p24 of HIV-1SF2 and a similar series across the p18 of HIV-1SF2 were used to identify the locations of 13 anti-gag monoclonal antibodies (MAbs). Three anti-p24 MAbs recognized sequences within the first 50 AA of the amino-terminal. Another anti-p24 recognized a conformational epitope in the centre of the protein and this MAb cross-reacted with two HIV-2 isolates suggesting conservation of this epitope between HIV-1 and HIV-2. One anti-p24 MAb recognized a linear sequence in the carboxy-terminal 100 AA and one p24 antibody was assumed to recognize a truly conformational epitope as it did not react with any of the linear peptides. Four anti-p18 MAbs were located at the carboxy-terminus of p18 with another MAb mapping slightly inwards from the carboxy-terminus and one anti-p18 MAb failed to bind to the p18 peptides. The carboxy-terminal distribution of the p18 MAbs indicated a highly immunogenic nature for this region in mice. None of the anti-p18 MAbs showed cross-reactivity with HIV-2 isolates, confirming the greater sequence variability of p18 over p24.