表达O型口蹄疫病毒衣壳蛋白的重组腺病毒构建及其免疫原性分析

Construction of recombinant adenovirus expressing capsid protein of serotype O foot-and-mouth disease virus and analysis of its immunogenicity

摘要:

为构建表达O型口蹄疫病毒（foot-and-mouth disease virus，FMDV）衣壳蛋白的复制缺陷型人5型腺病毒（Ad5）为载体的重组腺病毒，本研究设计、合成特异性引物并扩增出FMDV-OZK93的P12A、3B3C基因，通过融合PCR方法连接2个片段，获得P12A3B3C基因后插入到pDC316-mCMV-EGFP质粒，构建了能够表达FMDV-OZK93株衣壳蛋白前体P12A和3B3C蛋白酶的重组穿梭质粒pDC316-mCMV-EGFP-P12A3B3C。利用AdMax^TM腺病毒包装系统进行重组腺病毒rAdv-P12A3B3C-OZK93的包装、鉴定及扩增；并感染人胚胎肾细胞HEK-293进行表达验证。将鉴定正确且高度纯化后的重组腺病毒肌肉免疫小鼠进行免疫原性分析。结果显示，rAdv-P12A3B3C-OZK93在病毒传代过程中目的基因稳定存在，且病毒滴度可达1×10^9.1 TCID₅₀/mL。间接免疫荧光和Western blotting结果均表明rAdv-P12A3B3C-OZK93在HEK-293细胞中表达了FMDV特异性蛋白P12A和VP1。PK细胞感染实验证明rAdv-P12A3B3C-OZK93可感染猪源细胞，这为构建的rAdv-P12A3B3C-OZK93用于猪对抗FMDV的免疫与保护奠定了基础。相比于FMDV灭活疫苗免疫的小鼠，重组腺病毒免疫小鼠后可诱导机体产生更高水平的FMDV特异性抗体以及γ-IFN和IL-10应答反应，表明该重组腺病毒可对动物机体产生良好的免疫原性，为后续研制新型口蹄疫活载体疫苗奠定了重要基础。

Abstract:

In order to construct a recombinant replication deficient human type 5 adenovirus (Ad5) expressing a foot-and-mouth disease virus (FMDV) capsid protein, specific primers for P12A and 3B3C genes of FMDV-OZK93 were synthesized. The P12A and 3B3C genes were then amplified and connected by fusion PCR, and a recombinant shuttle plasmid pDC316-mCMV-EGFP-P12A3B3C expressing the FMDV-OZK93 capsid protein precursor P12A and 3B3C protease were obtained by inserting the P12A3B3C gene into the pDC316-mCMV-EGFP plasmid. The recombinant adenovirus rAdv-P12A3B3C-OZK93 was subsequently packaged, characterized and amplified using AdMax^TM adenovirus packaging system, and the expression was verified by infecting human embryonic kidney cell HEK-293. The humoral and cellular immunity levels of well-expressed and purified recombinant adenovirus immunized mice were evaluated. The results showed that rAdv-P12A3B3C-OZK93 could be stably passaged and the maximum virus titer reached 1×10^9.1 TCID₅₀/mL. Western blotting and indirect immunofluorescence showed that rAdv-P12A3B3C-OZK93 expressed the FMDV-specific proteins P12A and VP1 in HEK-293 cells. In addition, the PK cell infection experiment confirmed that rAdv-P12A3B3C-OZK93 could infect porcine cells, which is essential for vaccination in pigs. Comparing with the inactivated vaccine group, the recombinant adenovirus could induce higher FMDV-specific IgG antibodies, γ-IFN and IL-10. This indicates that the recombinant adenovirus has good immunity for animal, which is very important for the subsequent development of foot-and-mouth disease vaccine.