Objective To observe the safety and immune effect of live attenuated hepatitis A vaccine(H2 strain)produced by mono-layer absorption and suspension absorption with different virus harvest period in rhesus monkeys.
Methods Fifteen rhesus monkeys with negative anti-HAV and normal level of alanine transaminase(ALT)were selected and divided randomly into 3 groups. A group of 5 animals for 1 specimen and 1ml of vaccine was injected by Ⅳ into each rhesus monkey. The local and systemic reactions were observed within 3 days after injection. Both anti-HAV and ALT were detected at wk 0, 2, 3, 4, 6, 8 and liver puncture was performed at wk 0, 4, 8 for histopathological examination. Autopsy was down at the end of observation.
Results No local and systemic reactions were observed in any rhesus monkeys within 3 days after vaccination, The ALT levels were normal and no specific liver histopathological change were examined during whole period. The seroconversion rate of anti-HAV was 100%at 4 wk after inoculation. The GMTs were 9.2, 14.9, 27.9 for mono-layer absorption vaccine(26 d harvest), suspension absorption vaccine(23 d harvest) and suspension absorption vaccine(26 d harvest)at 4 wk and 32, 64, 64 at 8 wk. The immune effects induced by 2 suspension absorption vaccine were similar, but better than that mono-layer absorption.
Conclusion Suspension absorption with 23 d harvest technique vaccine possesses good safety and immune effect in rhesus monkey inoculation. The application of suspension absorption(23 d harvest)technique for production of hepatitis A vaccine(H2 strain)is economic and practicable.
DownLoad: