Proteolytic enzymes and rotavirus SA-11 plaque formation.

In addition to trypsin, eight other proteolytic enzyme preparations were tested for their ability to assist simian rotavirus SA-11 plaque formation in MA-104 cells. When incorporated in the overlay (minimal essential medium and 0.7% Ionagar No. 2) in the concentrations per mL indicated, alpha-chymotrypsin (10 micrograms), elastase (0.5 micrograms), subtilisin (0.5 micrograms), pronase (2.5 micrograms) and pancreatin (25 micrograms) were as efficient as trypsin (5 micrograms) in helping SA-11 produce 3-4 mm diameter plaques after five days of incubation at 37 degrees C. No plaques were produced when pepsin (25 micrograms), papain (10 micrograms) or thermolysin (10 micrograms) was added to the overlay. Addition of soybean trypsin inhibitor to alpha-chymotrypsin-, pronase- or pancreatin-containing overlays completely inhibited virus plaque production. A similar effect was not seen with elastase or subtilisin.