不同剂量配比的实验性甲型肝炎戊型肝炎联合疫苗的免疫原性研究

目的研究实验性甲型肝炎(甲肝)戊型肝炎(戊肝)联合疫苗的免疫原性,探讨两种抗原组分间的相互作用。方法制备9种不同剂量配比的实验性甲戊肝联合疫苗,与单价疫苗对照一起免疫15组(共120只)小鼠,定时采血,以ELISA和中和试验检测抗HAV和抗HEV的抗体。结果高剂量的HAV抗原(5×105U/L)与不同剂量的HEV抗原(200、100、50mg/L)配制的联合疫苗,诱导的抗HAV中和抗体的滴度可达1∶1024,含25×104、125×103U/LHAV抗原的联合疫苗诱导的中和抗体滴度为1∶512,不同剂量的HEV抗原对抗HAV中和抗体的产生均无明显影响。与单价戊肝疫苗相比较,联合疫苗诱导的抗HEV抗体水平均有明显升高,且随联合疫苗中HAV抗原的含量(5×105、25×104、125×103U/L)的增加而升高,HEV抗原的剂量在一定范围内(200、100、50mg/L)与抗HEV抗体产生无明显关系。采用基于逆转录套式PCR的中和试验表明,各联合疫苗组的免疫血清均可中和HEV。结论实验性甲、戊肝联合疫苗内HAV抗原对HEV抗原的免疫原性具有增强作用,而HEV抗原对HAV抗原的免疫原性无明显影响。

Immunogenicity of experimentally combined hepatitis A and hepatitis E vaccine at different dosage ratio

AIM: To evaluate the immunogenicity of experimentally combined hepatitis A and hepatitis E (cHA+E) vaccine and analyze the interactions between the two antigenic components in vaccine. METHODS: Nine different dosage ratio of the cHA+E vaccine, A500 + E200, A500 + E100, A500 + E50, A250 + E200, A250 + E100, A250 + E50, A125 + E200, A125 + E100 and A125 + E50 (U+mg)/L, was prepared from an inactivated hepatitis A (HA) vaccine and a hepatitis E (HE) vaccine. 120 mice were immunized with the cHA+E vaccine, HA vaccine and HE vaccine alone in different doses, respectively. Mice were bled before immunization and 2, 4, 6, 8, 10, 12 and 14 weeks post immunization. Specific antibodies against hepatitis A and E viruses were detected by ELISA and neutralization assay. RESULTS: After immunization with different dosages of cHA+E vaccine, all animals developed hepatitis A virus antibody (anti-HAV) and hepatitis E virus antibody (anti-HEV). Anti-HAV responses increased with the concentration of the HA vaccine component in the cHA+E vaccine. Anti-HAV neutralizing antibody titers reached 1:1 024 when mice were immunized with cHA+E vaccine prepared from higher dosage (500 U/mL) of the HA vaccine. The titers only reached 1:512 when lower dosages (250 and 125 U/mL) of HA vaccine were applied. However, different dosages (200, 100 and 50 mg/L) of the HE vaccine component in the cHA+E vaccine developed no effects on the production of anti-HAV neutralizing antibody. In addition, comparing with the single HE vaccine, the cHA+E vaccine induced higher level of anti-HEV response. The anti-HEV level increased with the concentration of HA vaccine component in the cHA+E vaccine. However, there was no obvious relationship between the anti-HEV levels and the different dosages (200, 100 and 50 mg/L) of the HE vaccine component in the cHA+E vaccine. Immune sera elicited by the cHA+E vaccine neutralized HEV infectivity when detected by an in vitro RT-nPCR-based HEV neutralization assay. CONCLUSION: In cHA+E vaccine, the HA vaccine component can increase the immunogenicity of the HE vaccine component, and the HE vaccine component plays no adverse effects on the immunogenicity of the HA vaccine component.