[Study on a purified and inactivated Japanese encephalitis vaccine prepared on Vero cells using SA14-14-2 attenuated virus strain].

OBJECTIVE: To develop a kind of new Japanese Encephalitis (JE) vaccine prepared on Vero cells. METHODS: A JE attenuated virus strain SA14-14-2 was adapted on Vero cells for preparation of purified inactivated vaccine. Comparison of the growth curves of SA14-14-2 in roller bottle and in spinner flask was made. After the virus inoculation and absorption on Vero cells for 2 hours, cultures were replaced with serum-free MEM, the culture supernatants were harvested on day 2,4,6 after inoculation. The virus fluids were pooled, concentrated by 8% PEG, and purified on 15%-60% sucrose density gradients. The purified virus was inactivated with 0.02% formalin. RESULTS: It showed that virus titer was higher and maintained longer in roller bottle. Mice vaccinated twicely with 0.5 microgram dose of the purified inactivated vaccine induced neutralizing antibody titers equal to that of the mice vaccinated with primary hamster kidney inactivated vaccine. CONCLUSION: This Vero cell prepared purified and inactivated JE vaccine made by SA14-14-2 strain could be used for human as a kind of new JE vaccine.