Effect of amino acid replacements, additions and deletions on the antiviral activity of a peptide derived from the HIV-1 GP41 sequence.

We demonstrated that a synthetic peptide (EWDREINNYTSLIHSLIEESQNQQEKNEQEGGC), designated SJ-2176, corresponding to the HIV-1 IIIB gp41 sequence (637-666), inhibited HIV-1 replication, virus-induced cell-cell fusion and cytopathic effects in both CD4+ T and monocytic cell lines. In this study, we show that lengthening the peptide at either the N- or C-terminus enhanced its activity, while shortening the peptide from either end decreased the antiviral activity. Substitution of conserved residues in SJ-2176 by alanines resulted in a decrease or elimination of antiviral activity. Replacement of arginine and lysine in the peptide by glutamines did not diminish antiviral activity and rendered the peptide resistant to trypsin.