NIAID In Vitro Test Results Comparing Onconase and P31
antiviral activity to Ganciclovir against Human Cytomegalovirus (HCMV)





The Facts:

What Is *Selectivity Index (SI)?

To determine the effectiveness of a drug, NIAID uses a Selectivity Index (SI) as criteria to determine the potency of a drug. The SI measures CC50 (amount of drug required to kill 50% of uninfected cells) and EC50 (amount of drug needed to cause 50% inhibition of viral replication). CC50 divided by EC50=SI. A higher SI demonstrates greater overall antiviral activity.



The Results:

The in vitro results, which were performed in cell culture and in plaque reduction assay (the gold standard)
showed Onconase and P31 to be between 3 and 11 times more potent than Ganciclovir
in a head-to-head comparison.

In cell culture, it took Ganciclovir (156) times more drug compared to Onconase to achieve 50% inhibition of viral replication.

In Plaque Reduction Assay, it took Ganciclovir (331) times more drug compared to Onconase to achieve 50% inhibition of viral replication.