SARS灭活疫苗毒种特性和效力试验方法的研究和建立

Establishing animal models for evaluation of potency of inactivated SARS virus vaccine and virus seed

目的验证SARS灭活疫苗生产用毒种和建立疫苗效力试验方法和评价疫苗有效性的方法和初步标准。方法将SARS灭活疫苗进行系列稀释后免疫小鼠、原液疫苗免疫家兔,用异株病毒作为攻击毒以蚀斑减少法测定血清中和抗体,并与一组SARS病人恢复期血清的中和抗体水平进行比较,初步建立疫苗的效力试验方法和评价标准。结果疫苗以不同稀释度免疫小鼠,能产生随不同稀释度疫苗相应梯度的中和抗体滴度,用原倍疫苗免疫的小鼠血清中和抗体可达495.2;原倍疫苗免疫家兔所产生的中和抗体GMT为55.0～79.9。无论是小鼠或家兔所产生的中和抗体对广东分离的病毒均较北京分离的病毒为高。南北不同区域的SARS病人恢复期血清中和抗体GMT为50.12～54.95,且发现北方人群样本的抗体高于南方人群样本。结论用小鼠和家兔作疫苗的效力试验模型具有较好的敏感性和重复性,且产生的抗体水平较高;选用的攻击病毒对多批用不同毒株生产的疫苗免疫后的动物抗体具有较高的一致性,可用于评价疫苗的效力。

Objective To verify immunogenicity of source virus strain for the manufacture of inactivated SARS virus vaccine and establish an experimental method and preliminary standard for potency appraisal. Method Identifying and verifying vaccine seed, virus source and viral strain by testing viral titer;Conducting identity tests, and examining viral adventitious agents test in accordance with China Requirements for Biologics and WHO＇s relative requirements; Vaccinated mice with diluting the candidate vaccine for 2 time serially and vaccinated rabbits with undiluted vaccine; Using other virus strains isolated from different areas as the challenge virus; Testing neutralizing antibodies in serum of vaccinated animals with the PRNT （Plaque Reduction Neutralization Test） method, and comparing it with antibody levels obtained from convalescent SARS patients to establish an experimental method and standard for evaluated vaccine potency. Result Candidate vaccine viral strains were proven to be a suitable source for manufacturing human-use-vaccine. Those immunized by vaccines of serial dilutions are able to elicit respondent titers of neutralizing antibody. The titer from mice immunized with the undiluted vaccine could reach up to 1：495.2, while rabbits with the undiluted vaccine could reach a GMT of 55.0～79.9. Neutralizing antibody titers reacting to virus strain from Guangdong higher than that from Beijing. GMT of neu isolated,produced both by mice and rabbits, were tralizing antibody in SARS convalescents living in southern and north China ranged from 50.12 to 54.95, and titers of convalescents from north China were higher than those from southern China. Conclusion Mice/rabbit-based vaccine-potency- model is good for sensitivity and reproducibility, and is able to produce a higher antibody titer. The candidate challenge viral strains showed a relatively consistent effect on evaluating antibodies produced by various batches and different vaccine-source strains, hence they can be used to appraise potency of vaccine.