不同剂量甲型肝炎减毒活疫苗免疫原性与免疫持久性观察

摘要

Objective　This study was carried out to assess the long-term persistence of antibodies against hepatitis A in different vaccine dosage groups. Methods　One hundred and sixty-six susceptibles aged form 6 to 8 years old were selected in Zhengding county, and were divided into 4 different dose groups. Each group received 106.17TCID50, 106.52TCID50, 106.83TCID50 of attenuated hepatitis A vaccine or 106.83TCID50 of the same vaccine but treated with 60℃ for 3 hours. All subjects were bled at month 3, 12, 24, 36 and 48. All serum specimens were tested for antibodies to HAV using Abbott-IMx mEIA reagent. Part of the tested negative serum specimens were retested by neutralization assay for 106.52TCID50 and 106.83TCID50 doseage groups at 4 years after vaccination. Results　The seroconversion rate and GMT 3 months after vaccination in each dosage group showed a significant dose-response relationship. Antibody levels reached the peak at month 3 in each group but declined dramatically within one year and the decline slowed down thereafter. The serocoversion rate and GMT in 106.83TCID50 dose group 4 years after vaccination was significant higher than those of other dosage groups. Positive rates of neutralizing antibodies in B and C dosage group were 60.0% and 83.3% respectively. Conclusion　The immunogenicity and long-term persistence were related to the attenuated hepatitis A vaccine titer. The vaccine, whose titer was 106.83TCID50, had good immunogenicty and long-term persistence. Booster dose was not needed within short time after initial vaccination.%目的　观察不同剂量的甲型肝炎(甲肝)减毒活疫苗免疫原性与免疫持久性。 方法　对河北省正定县4个村166名6～8岁事先经血清检测抗-HAV阴性的易感儿童，按村分成4组，分别给予0.5、1、2及2剂经60℃ 3 h灭活处理的甲肝减毒活疫苗(滴度为106.52TCID50)。并于接种后3、12、24、36及48个月采集观察对象血清，采用Abbott-IMx mEIA试剂检测血清抗-HAV。并对接种1剂、2剂活疫苗组免后4年部分血清检测中和抗体。 结果　免后3个月抗体阳转率、抗体几何平均滴度(GMT)同疫苗滴度呈剂量效应关系。免疫后各组抗体水平于免疫后3个月达高峰后逐年下降，12个月内下降较明显，12个月后下降缓慢。免疫后4年接种2剂活疫苗组抗体阳性率与GMT均高于接种0.5剂及1剂组。接种1、2剂活疫苗组部分经Abbott-IMx mEIA试剂检测抗-HAV阴性的血清检测中和抗体，其阳性率为60％及83％。 结论　甲型肝炎减毒活疫苗的免疫原性与免疫持久性同疫苗的滴度有关，滴度为106.83TCID50的减毒活疫苗具有较理想的免疫原性及免疫持久性。减毒活疫苗接种后近期内不必予以加强免疫。