Differential and Specific Inhibition of ECHO Viruses by Plant Extracts.

Abstract

Study of several plant extracts using monkey kidney cell culture showed that M2, prepared from a strain of Calvatia gigantea significantly inhibited only ECHO 4 and 11; while M4, a different preparation from the same strain, inhibited only ECHO 7 and 8; and M14, from a species of Cattleya inhibited ECHO 2. The effectiveness of M2 in vitro was greatest when the cells were pretreated and when the virus inocula did not exceed 100 TCID50. The specificity of the antiviral action of M2 was demonstrated by the inhibition of one M2-susceptible virus followed in the same culture by growth of a second M2-unsusceptible virus. Inhibition continued, however, if the cultures were reinoculated with a second M2-susceptible virus. Activity of M2 was demonstrated in vivo by its ability to suppress the antigenicity of an M2-susceptible virus. The results demonstrate the capacity of certain substances to prevent infection of susceptible cells by specific viruses although the cells retain their physiologic competence to support growth of other viruses and the virus is not directly affected by the inhibitory material.