Antiviral melanization reaction of Heliothis virescens hemolymph against DNA and RNA viruses in vitro.

1. Antiviral activity of Heliothis virescens larval hemolymph was determined using a cytotoxicity/virus inhibition test (TClD50) done in Vero cell tissue cultures. Excellent antiviral activity was found especially against herpes simplex viruses-1 and -2 and also against vesicular stomatitis, parainfluenza-3, coxsackie B3 and sindbis viruses. 2. Prolonged incubation of herpes simplex virus-1 and vesicular stomatitis virus with hemolymph was virucidal and greatly reduced infectivity of the two viruses in tissue culture. 3. Antiviral activity was produced by both normal and immune (vaccinated larvae) cell-free hemolymphs. 4. Antiviral activity against herpes simplex virus-1 could be generated in vitro with hemolymph phenoloxidase or mushroom tyrosinase using four different substrates including tyrosine. 5. Activation of the insect melanization reaction by phenoloxidase was necessary for antiviral activity to occur.