INHIBITION OF THE INTEGRASE OF HUMAN-IMMUNODEFICIENCY-VIRUS (HIV) TYPE-1 BY ANTI-HIV PLANT-PROTEINS MAP30 AND GAP31

MAP30 (Momordica anti-HIV protein of 30 kDa) and GAP31 (Gelonium anti- HIV protein of 31 kDa) are anti-HIV plant proteins that we have identi fied, purified, and cloned from the medicinal plants Momordica charant ia and Gelonium multiflorum. These antiviral agents are capable of inh ibiting infection of HIV type 1 (HIV-1) in T lymphocytes and monocytes as well as replication of the virus in already-infected cells, They a re not toxic to normal uninfected cells because they are unable to ent er healthy cells, MAP30 and GAP31 also possess an N-glycosidase activi ty on 28S ribosomal RNA and a topological activity on plasmid and vira l DNAs including HIV-1 long terminal repeats (LTRs), LTRs are essentia l sites for integration of viral DNA into the host genome by viral int egrase, We therefore investigated the effect of MAP30 and GAP31 on HIV -1 integrase, We report that both of these antiviral agents exhibit do se-dependent inhibition of HIV-1 integrase, Inhibition was observed in all of the three specific reactions catalyzed by the integrase, namel y, 3' processing (specific cleavage of the dinucleotide GT from the vi ral substrate), strand transfer (integration), and ''disintegration'' (the reversal of strand transfer), Inhibition was studied by using oli gonucleotide substrates with sequences corresponding to the U3 and U5 regions of HIV LTR, In the presence of 20 ng of viral substrate, 50 ng of target substrate, and 4 mu M integrase, total inhibition was achie ved at equimolar concentrations of the integrase and the antiviral pro teins, with EC(50) values of about 1 mu M. Integration of viral DNA in to the host chromosome is a vital step in the replicative cycle of ret roviruses, including the AIDS virus, The inhibition of HIV-1 integrase by MAP30 and GAP31 suggests that impediment of viral DNA integration may play a key role in the anti-HIV activity of these plant proteins.