Improvements in the Tissue Culture Safety Testing of Salk Vaccines

Under the conditions of the official Canadian test, it was found that two simultaneous first-order reactions were in competition. Thus, after 4 hours, while 15% of any initial live MEF1 poliovirus present was adsorbed to the monkey kidney cells, 9% of the virus was destroyed by spontaneous inactivation. When the adsorption rate was increased by decreasing the volume of fluid, it was found that significantly more isolations of virus were obtained. Utilizing the method of Baron for the concentration of polio virus it was found possible to maintain a low test volume without making the routine test unduly cumbersome. The modified test is simpler and more sensitive and may be used with undialyzed vaccines.