Competition between tuftsin and HIV-1, HIV-2 envelope protein sequences.

Syntheses of tuftsin-like partial sequences of HIV-1 and HIV-2 gp-120 proteins: Thr-Lys-Ala-Lys (I), Thr-Lys-Ala-Lys-Arg (II), Pro-Thr-Lys-Ala-Lys-Arg (III), Thr-Lys-Glu-Lys (IV), Thr-Lys-Glu-Lys-Arg (V), and Pro-Thr-Lys-Glu-Lys-Arg (VI) are described. From HIV-1 partial sequences peptide I inhibited the phagocytosis stimulating activity of tuftsin. The inhibitory potency diminished progressively for peptides II and III, in parallel to the increase of their slight phagocytosis stimulating activity. Similar results were obtained also for the fragments of the HIV-2 gp120 protein. The inhibitory activity, clearly visible for IV, diminished with peptide chain elongation. Peptides IV and VI were devoided of the phagocytosis stimulating activity while peptide V was slightly active.