The detection and inhibition of proteolytic enzyme activity in concentrated preparations of inactivated foot-and-mouth disease virus.

Proteolytic enzyme activity was detected in a large number of concentrated preparations of inactivated foot-and-mouth disease virus. Several lines of evidence indicated that at least some of this activity could be attributed to BHK cells, although low levels of microbial contamination in many of our preparations could not be discounted and would certainly enhance the cellular proteolytic activity. From an experiment with different concentrations of trypsin, it was concluded that the proteolytic activities of virus concentrates were sufficient to cause significant degradation of VP1. It was also shown that Trasylol and ox serum were effective inhibitors of proteolytic enzymes in concentrated virus preparations stored at 4 degrees C for 8 months.