Hypovirus/Cryphonectria Parasitica As A Model In Screening Antiviral Compounds

Drug screening models are used to prove whether a substance has potentialfor medical treatment and is a key step in new drug development. An idealmodel should posses an obviously detectable marker and with high throughout.However, there are few ideal screening methods for most of RNA viruses,especially for the plant virus and mycovirus.The virus-free chestnut blight fungus, Cryphonectria parasitica, were whencultured on solid PDA or liquid EP complete media. These phenotypes turned towhite once the fungus was infected by a hypovirus. When virus get lost, thefungus turned to orange again. This change in pigmentation provided a goodmarker for indication of the existence and the concentration of virus in the hostfungus.In this study, mycelium pigmentation was used as a primary marker for thescreening of potent compound effective against a hypovirus. Commercial broadspectrum antiviral drugs were applied to the virus-containing Cryphonectriaparasitica strains to evaluate their efficacy in releasing, the symptom andreducing the viral level in the host cells.The results suggested that pigmentation was most sensitive in response tomany antiviral drugs. Real-time PCR revealed that the reduction in virus dsRNA was positively correlated with the change of pigmentation in hyphae. Dosageresponse was obvious in both pigment restoration and virus dsRNA reductionthat was measured by real-time RT-PCR. This phenomenon was the mostobvious in EP721/EP721(-), with Euro7/Euro7(-) ranked second, and leastobvious in EP713/EP155. Since EP721 has the highest rate of virus-escape,Euro7/Euro7(-) seemed to be the best system for antiviral compound screening.