Inhibition of Herpes Simplex Virus Strains Isolated from Herpetic Keratitis by Polyinosinic Acid-Polycytidylic Acid

Abstract

Fifty strains of herpes simplex virus, isolated from patients with herpetic keratitis, were examined in vitro for susceptibility to polyinosinic acid-polycytidylic acid [poly(I:C)] in the presence of a constant concentration of diethylaminoethyl-dextran. The minimal inhibitory concentration of poly(I:C) for 44 of these strains ranged from 0.0001 to 0.1 μg/ml; for the remaining six strains, the minimal inhibitory concentration stood at 1 to 2 μg/ml. Fifteen isolates from primary infections were more susceptible to poly(I:C) than 35 isolates from recurrent infections. Isolates acquired at different points of a given clinical episode showed similar susceptibilities to poly(I:C). In two patients, isolates from consecutive recurrences of infection exhibited reduced susceptibilities. The implications of the above observations for the therapeutic use of poly(I:C) are discussed.