三带喙库蚊和致倦库蚊经口感染乙型脑炎病毒疫苗SA14-14-2株的研究

目的通过实验，确定被SA14—14—2乙脑减毒活疫苗免疫的宿主动物和人在被媒介蚊虫叮咬后，是否存在感染和传播的可能。方法建立三带喙库蚊和致倦库蚊的实验室种群，用乙型脑炎SA14—14—2疫苗株病毒和乙脑野毒株经口感染两种库蚊，感染后不同时间取一定数量的蚊，研磨制成悬液，应用空斑试验方法检测感染后不同时间蚊体内的病毒存在情况和病毒滴度。结果在用6．0610gPFU／ml SA14～14—2病毒经口感染的两种库蚊中，没有检测到病毒空斑，即没发现蚊虫的感染；在用较高的6．1810gPFU／ml病毒经口感染的三带喙库蚊和致倦库蚊中，分别有一组蚊虫出现低滴度感染，空斑形成单位分别是1．24和1．11log10PFU／ml；在用野毒株经口感染的两种库蚊，共计19组蚊虫中，有14组发生感染，空斑形成单位在3．18～4．7910g10PFU／ml。结论作为乙脑主要传播媒介的三带喙库蚊和致倦库蚊对SA14—14—2疫苗株病毒的经口感染和病毒在体内的复制严重受限，当叮咬接种疫苗的人后，不具备发生乙脑病毒感染和传播的能力。

Studies on Culex tritaeniorhynchus and Culex pipiens quinquefascitatus infected orally by Japanese encephalitis SA14-14-2 vaccine virus

To study on the ability of JE SA14-14-2 vaccine virus to infect and replicate in the JE mosquito vectors by oral infection,laboratory strains of two species vector mosquitoes, Culex tritaeniorhynchus and Culex pipiens quinquefascitatus, were set up and the mosquitoes were exposed to the virus suspension meals by oral ingestion. Different days after ingestion, pools of the mosquitoes were detected for the virus content by plaque assay. When the virus meals containing 6.06log pfu/ml SA14-14-2 virus, no virus could be detected in both species of mosquitoes at any times;but when it contained higher level of vaccine virus(6.18logpfu), low titers(1.11 and 1.24log pfu)of the virus could be detected in one mosquito pool in each of the two species. In contract ,when the wild strain of JE virus wild virus was used for ingestion, high frequency of the mosquito pools (14/19) with high virus titers(3.18-4.79logpfu)were detected. These results indicates that the attenuated virus is highly restricted in its ability to infect and replicate in both JE mosquito vectors. It demonstrates the safeguards against secondary spread of the vaccine virus by the JE mosquito vectors.