HIV-1 REVERSE-TRANSCRIPTASE - INHIBITION BY 2',5'-OLIGOADENYLATES

2',5'-Oligoadenylates (2-5A) and derivatives are noncompetitive inhibi tors of primer/HIV-1 reverse transcriptase complex formation. The mech anism and specificity of this inhibitory action of 2-5A and 2-5A deriv atives have been evaluated with 2-5A molecules modified in ribosyl moi ety, chain length, extent of 5'-phosphorylation, and 2',5'-phosphodies ter linkage. UV covalent cross-linking of preformed complexes of p66/p 66 homodimer or p66/p51 heterodimer recombinant HIV-1 reverse transcri ptase and the primer analog pd(T)16 allowed analysis of the initial st ep in HIV-1 reverse transcriptase-catalyzed DNA synthesis. Utilizing t his primer binding assay, it is demonstrated that 2-5A and 2-5A deriva tives inhibit the binding of pd(T)16 to HIV-1 reverse transcriptase. T his inhibition is specific for the 2',5'-internucleotide linkage in th at the corresponding 3',5'-adenylate derivatives do not exhibit inhibi tory activity. Enhanced inhibitory properties were observed following modifications of the 2-5A molecule which result in an increase in hydr ophobicity. Replacement of the D-ribosyl moiety of 2-5A with the 3'-de oxyribosyl moiety increased the inhibition of primer/HIV-1 reverse tra nscriptase complex formation 15-20%. 2',5'-Phosphorothioate substituti on yielded the most effective inhibitors, with K(i)'s of 7-13 muM. In all cases, inhibition of primer/HIV-1 reverse transcriptase complex fo rmation showed a preference for the 5'-triphosphate moiety. Nonphospho rylated derivatives were not inhibitory; 5'-monophosphate derivatives exhibited little or no inhibition. The inhibition of primer binding to HIV-1 reverse transcriptase correlated well with the inhibition of DN A-directed DNA synthesis. Introduction of R(P) chirality into the 2',5 '-phosphodiester bond, i.e., 2',5'-p3A3alphaS, resulted in the most po tent noncompetitive inhibitor of primer/HIV-1 reverse transcriptase co mplex formation. This 2-5A-mediated inhibition of HIV-1 reverse transc riptase may represent part of the anti-HIV-1 activity of interferon.