Development of Determination Method for Infectious Titer of SV40 and Preparation of High Titer Virus

Objective To develop a stable determination method for infectious titer of SV40 and prepare high titer SV40 used for the validation of virus removal/inactivation procedure of biologics. Methods Analyze the time when CPE appears,the degree of CPE and virus yield of various cells after infection with SV40 to screen SV40-sensitive cell strain.Analyze the effects of maintain medium,time for culture and time for virus adsorption on the virus titration to develop a method for determination of SV40 titer.Analyze the variation of SV40 titers at various hours after infection and at various sites of cells to prepare high titer SV40 in a large quantity. Results Compared with Vero,Vero 76 and VeroE6 cells,CV-1 cells were more sensitive to SV40,in which the CPE appeared earlier and was more significant,and the virus yield was higher.SV40 virus titer showed no significant relationship to the time for culture of cells before inoculation,concentration of cells inoculated and cell maintain medium.However,the time for virus adsorption showed a certain influence on virus titer.The optimal time for virus adsorption was 120 min.The mean titer of SV40 harvested 48 h after inoculation was 8.81 CCID 50 /ml. Conclusion A stable method for determination of SV40 titer was developed,and high titer SV40 was prepared.It laid a foundation of validation of virus removal/inactivation procedure of biologics.