Testing of antiviral compounds against Mengo virus infection of mice. A 2-step procedure of in vivo screening.

A 2-step procedure of screening of antiviral compounds in vivo is presented on the basis of standardized methods of both experimental examination and statistical analysis. The procedure uses the "rate of protection" R as the sole criterion of activity. In the first step, requiring a total of 40 mice, compounds with significant R are detected. Drugs producing R less than 15% are discarded. Compounds eliciting R larger than or equal to 15%, without significance, are examined in a second step, using again 40 mice, to decide whether the protective activity becomes significant employing a greater number of animals. The procedure works with relatively less expense with regard of the number of animals used and the time required. The procedure can be applied to test systems based on lethal infections as well as to test models for which the use of the "rate of protection" is relevant.