Synthetic CD4 Peptide Derivatives That Inhibit HIV Infection and Cytopathicity

Abstract

Synthetic peptide segments of the CD4 molecule were tested for their ability to inhibit infection of CD4+ cells by the human immunodeficiency virus (HIV) and to inhibit HIV-induced cell fusion. A peptide mixture composed of CD4(76-94), and synthesis side products, blocked HIV-induced cell fusion at a nominal concentration of 125 micromolar. Upon high-performance liquid chromatography, the antisyncytial activity of the peptide mixture was found not in the fraction containing the peptide CD4(76-94) itself, but in a side fraction containing derivatized peptide products generated in the automated synthesis. Derivatized deletion and substitution peptides in the region CD4(76-94) were used to demonstrate sequence specificity, a requirement for benzyl derivatization, and a core seven-residue fragment required for antisyncytial activity. A partially purified S-benzyl-CD4(83-94) peptide mixture inhibited HIV-induced cell fusion at a nominal concentration of less than or equal to 32 micromolar. Derivatized CD4 peptides blocked cell fusion induced by several HIV isolates and by the simian immunodeficiency virus, SIV, and blocked infection in vitro by four HIV-1 isolates with widely variant envelope gene sequences. Purified CD4(83-94) dibenzylated at cysteine 86 and glutamate 87 possessed antisyncytial activity at 125 micromolar. Derivatization may specifically alter the conformation of CD4 holoreceptor peptide fragments, increasing their antiviral efficacy.

A monoclonal antibody to the gp120-CD4 complex has differential effects on HIV-induced syncytium formation and viral infectivity

“…Investigations on the regions of CD4 other than the gp 120 binding site involved in HIV-1 envelope-mediated membrane fusion have provided contradictory data (Lifson et al, 1988;Camerini & Seed, 1990;Ohki et al, 1990;Rausch et al, 1992;Broder & Berger, 1993). The role of the anti-CDR3 MAb 13B8-2, specific for sequences surrounding amino acid 87, is also controversial.…”

Chromogranin A: current status as a precursor for bioactive peptides and a granulogenic/sorting factor in the regulated secretory pathway

“…Potent non-peptide inhibitors of L-type calcium-dependent voltage channels have been identified as low-molecular weight contaminants extractable from plasticware frequently used in peptide purification [141]. Thus, even in purified or synthetic preparations of peptides, no biological activity can reasonably be attributed to the peptide present in the mixture unless biological activity is preserved upon acid treatment or boiling, preserved upon treatment with presumptive processing enzymes, and most importantly, abolished by Pronase treatment (e.g., [142]). …”

“…Chromostatin is a fragment of chromogranin A (CGA- (124)(125)(126)(127)(128)(129)(130)(131)(132)(133)(134)(135)(136)(137)(138)(139)(140)(141)(142)(143) in the cow) which represents a special case of potential extracellular processing of CGA. Simon and co-workers described an inhibitory effect of purified chromogranin A on catecholamine release from the adrenal medulla.…”

Multibranched V3 peptides inhibit human immunodeficiency virus infection in human lymphocytes and macrophages

“…Preliminary data from our group (12) suggested that they could act, at least in part, by occluding a region of CD4 (i.e., CDR3) which may be important for the fusion process (21,22,37). These results are supported by biochemical studies previously reported by Autiero et al (1).…”