Gowal D, Tahlan A K
Japanese Encephalitis Vaccine Division, Central Research Institute, Kasauli.
Indian J Med Res. 1995 Dec;102:267-71.
Efficacy of mouse brain inactivated Japanese encephalitis vaccine was evaluated by studying the immune status of volunteers 1,2,3,4.5 and 7.5 yr after immunization. Neutralizing (N) antibody which is protective and found to correlate with the immunity after vaccination was estimated in serum by plaque reduction neutralizing test on chick embryo cell monolayer. Mean N-antibody titres of 3.25 (pre-booster) and 3.6, 2.8, 2.06, 1.85 and 1.50 log10 were observed post-booster, and 1,2,3, and 4.5 yr of immunization in volunteers who received complete immunization (3 doses). All the volunteers retained more than 1.0 log10 titre of protective N-antibody in spite of the loss of 0.8, 0.74, 0.21 and 0.35 log10 after 1,2,3, and 4.5 yr respectively. Similarly mean N-antibody titres of 1.6, 3.25, 2.4, 2.25, 1.92 and 1.60 log10 were observed pre-booster, after a single booster dose, and 1,2,3 and 4.5 yr of vaccination in individuals who received only a single booster dose. Ten serum samples of volunteers tested after 7.5 yr of vaccination showed that those who were in constant contact with JE virus (n = 7) in the laboratory maintained high levels of N-antibody whereas others (n = 3) showed a fall in titre indicating the necessity of a booster dose.
通过研究志愿者免疫后1年、2年、3年、4.5年、5年和7.5年的免疫状态，评估了鼠脑灭活乙型脑炎疫苗的效力。通过在鸡胚细胞单层上进行蚀斑减少中和试验，估计血清中具有保护作用且发现与疫苗接种后免疫力相关的中和（N）抗体。在接受全程免疫（3剂）的志愿者中，加强免疫后以及免疫后1年、2年、3年和4.5年观察到的平均N抗体滴度分别为3.25（加强免疫前）和3.6、2.8、2.06、1.85和1.50 log10。尽管在1年、2年、3年和4.5年后分别下降了0.8、0.74、0.21和0.35 log10，但所有志愿者仍保持超过1.0 log10滴度的保护性N抗体。同样，在仅接受一次加强免疫的个体中，加强免疫前、单次加强免疫后以及接种疫苗后1年、2年、3年和4.5年观察到的平均N抗体滴度分别为1.6、3.25、2.4、2.25、1.92和1.60 log10。接种疫苗7.5年后检测的10份志愿者血清样本显示，那些在实验室中经常接触乙脑病毒的人（n = 7）保持较高水平的N抗体，而其他人（n = 3）滴度下降，表明需要加强免疫。
