[Design and immunogenicity evaluation for the bacteria-like particle vaccine against swine type O foot-and-mouth disease virus]

Based on gram positive enhancer matrix displaying technology, we designed and evaluated a bacteria-like particle vaccine against swine type O Foot-and-mouth disease virus. Three optimized genes of type O Foot-and-mouth disease virus strain Mya98 were cloned into recombinant prokaryotic expression vector pQZ-PA and renamed as pQZ-BT1B-PA, pQZ-BT2B-PA and pQZ-B (T1BT2) 4B-PA, fused with an anchor protein (PA) binding to Gram-positive enhancer matrix (GEM) particles specifically. The protein expression was identified with SDS-PAGE and Western blotting, and then purified with GEM particles. Five-week old female mice were randomly divided into six groups and all the immunization was developed according to subcutaneous injection. Mice in the first three groups were injected with 50 μg/dose GEM-BT1B, GEM-BT2B and GEM-B (T1BT2) 4B, respectively. Mice in the fourth group were immunized with commercial peptide vaccine as positive control. The fifth group vaccinated with host E. coli transformed with pQZ-PA fulfilled as negative control. Mice in the last group injected with sterile PBS served as blank control. The humoral immunity of recombinant protein vaccine was evaluated with peptide-specific antibody and LPB antibody. The cellular immunity was evaluated with lymphocyte proliferation test and cytokine expression detection. SDS-PAGE and Western blotting showed that the most part of soluble target fusion protein have been purified and displayed on GEM particles. Vaccine GEM-B (T1BT2) 4B stimulated mice produce not only higher level of specific antibody against peptide and Foot-and-mouth disease virus specific liquid phase blocking antibody, but also more vigorous spleen lymph proliferation and higher levels of Th1 type cytokines. To summarize, vaccine of GEM-B (T1BT2) 4B possessed good immunogenicity and opened a new way for further Foot-and-mouth disease virus subunit vaccine design.验证基于革兰氏阳性增强基质 (Gram-positive enhancer matrix，GEM) 展示口蹄疫病毒细菌样颗粒(Bacteria-like particles，BLP) 疫苗的可行性。按照大肠杆菌偏好性密码子优化合成基于猪口蹄疫病毒Mya98株序列的3 种抗原基因设计，并将其插入到含有锚钩蛋白基因的原核表达载体pQZ-PA，鉴定阳性后转入Escherichia coli BL21，进行诱导表达。利用SDS-PAGE 与Western blotting 对目的基因表达及产物的可溶性进行分析。利用GEM 颗粒纯化目的蛋白，制备细菌样颗粒疫苗抗原；利用BCA 试剂盒测定重组蛋白的浓度，将重组蛋白与白油佐剂乳化，制备疫苗，免疫5 周龄小鼠，同时设商品化多肽苗对照与空白对照，免疫后不同时间采集试验小鼠血清，利用口蹄疫病毒多肽ELISA 抗体检测试剂盒和O 型口蹄疫抗体液相阻断酶联免疫(Enzyme-linked immunosorbent assay，ELISA) 检测试剂盒检测免疫小鼠血清的抗体水平；利用噻唑蓝比色法(Methylthiazolyldiphenyl-tetrazolium bromide，MTT) 测定淋巴细胞增殖情况；利用荧光定量PCR 方法检测相关细胞因子表达，评价细胞免疫水平。SDS-PAGE 结果表明，设计在大肠杆菌中的3 种口蹄疫病毒抗原基因均以可溶形式获得高效表达；Western blotting 结果显示，表达的重组蛋白能够与口蹄疫病毒阳性血清发生反应，利用GEM 颗粒能够实现重组蛋白的一步离心纯化，制备BLP 疫苗抗原；免疫试验结果表明，设计的重组抗原B (T1BT2) 4B 不但能够刺激免疫小鼠产生更高水平的多肽特异性ELISA 抗体与口蹄疫特异性液相阻断抗体，而且产生了更高水平的脾淋巴细胞增殖及Th1 型的细胞因子分泌。初步实验结果表明，本研究制备的BLP 疫苗GEM-B (T1BT2) 4B 具有良好的免疫原性，为研究口蹄疫病毒基因工程亚单位疫苗开辟了一条新的思路。.