CONSTRUCTION AND ENHANCED CYTOTOXICITY OF A [CYANOVIRIN-N]-[PSEUDOMONAS EXOTOXIN] CONJUGATE AGAINST HUMAN IMMUNODEFICIENCY VIRUS-INFECTED CELLS

Cyanovirin-N (CV-N) is a novel 11-kDa anti-HIV(human immunodeficiency virus) protein that binds with high affinity to the viral envelope gly coprotein gp120, in contrast to soluble CD4 and most known neutralizin g antibodies that bind gp120, CV-N exerts potent anti-viral activity a gainst primary clinical HN isolates as well as laboratory-adapted stra ins of HIV. Here we describe the recombinant production, purification, and characterization of a chimeric toxin molecule, FLAG-CV-N-PE38, th at contains CV-N as a gp120-targeting moiety linked to the translocati on and cytotoxic domains of Pseudomonas exotoxin A. FLAG-CV-N-PE38 sho wed enhanced cytotoxicity to HIV-infected, gp120-expressing H9 cells c ompared to uninfected H9 cells. Competition experiments with free CV-N provided further support that the enhanced FLAG-CV-N-PE38-induced cyt otoxicity was due to interactions of the CV-N moiety with cell surface gp120. This study establishes the feasibility of use of CV-N as a gp1 20-targeting sequence for construction and experimental therapeutic in vestigations of unique new chimeric toxins designed to selectively des troy HIV-infected host cells. (C) 1997 Academic Press.