Lanzhou Veterinary Research Institute of Chinese Academy of Agriculture Science, State Key Laboratory of Veterinary Etiological Biology, National Foot-and-Mouth Disease Reference Laboratory, Key Laboratory of Animal Virology of Ministry of Agriculture, Xujiaping No 1, Yanchangpu, Lanzhou, Gansu 730046, PR China.
Virol J. 2011 Feb 23;8:77. doi: 10.1186/1743-422X-8-77.
Foot-and-mouth disease (FMD) is a highly contagious disease of livestock which causes severe economic loss in cloven-hoofed animals. Vaccination is still a major strategy in developing countries to control FMD. Currently, inactivated vaccine of FMDV has been used in many countries with limited success and safety concerns. Development of a novel effective vaccine is must.
In the present study, two recombinant pseudotype baculoviruses, one expressing the capsid of foot-and-mouth disease virus (FMDV) under the control of a cytomegalovirus immediate early enhancer/promoter (CMV-IE), and the other the caspid plus a T-cell immunogen coding region under a CAG promoter were constructed, and their expression was characterized in mammalian cells. In addition, their immunogenicity in a mouse model was investigated. The humoral and cell-mediated immune responses induced by pseudotype baculovirus were compared with those of inactivated vaccine.
Indirect immunofluorescence assay (IFA) and indirect sandwich-ELISA (IS-ELISA) showed both recombinant baculoviruses (with or without T-cell epitopes) were transduced efficiently and expressed target proteins in BHK-21 cells. In mice, intramuscular inoculation of recombinants with 1 × 109 or 1 × 1010 PFU/mouse induced the production of FMDV-specific neutralizing antibodies and gamma interferon (IFN-γ). Furthermore, recombinant baculovirus with T-cell epitopes had better immunogenicity than the recombinant without T-cell epitopes as demonstrated by significantly enhanced IFN-γ production (P < 0.01) and higher neutralizing antibody titer (P < 0.05). Although the inactivated vaccine produced the highest titer of neutralizing antibodies, a lower IFN-γ expression was observed compared to the two recombinant pseudotype baculoviruses.
These results indicate that pseudotype baculovirus-mediated gene delivery could be a alternative strategy to develop a new generation of vaccines against FMDV infection.
口蹄疫（FMD）是一种高度传染性的牲畜疾病，会给偶蹄类动物造成严重的经济损失。疫苗接种仍然是发展中国家控制 FMD 的主要策略。目前，在许多国家使用的 FMDV 灭活疫苗取得了一定成效，但存在安全性方面的担忧。因此，开发新型有效疫苗迫在眉睫。
本研究构建了两种表达口蹄疫病毒（FMDV）衣壳的重组假型杆状病毒，一种在巨细胞病毒立即早期增强子/启动子（CMV-IE）的控制下表达，另一种在 CAG 启动子的控制下表达衣壳和 T 细胞免疫原编码区。并在哺乳动物细胞中对其表达情况进行了表征。此外，还在小鼠模型中研究了它们的免疫原性。比较了假型杆状病毒诱导的体液免疫和细胞免疫应答与灭活疫苗的差异。
间接免疫荧光法（IFA）和间接夹心 ELISA（IS-ELISA）显示，两种重组杆状病毒（带或不带 T 细胞表位）均能有效地转导并在 BHK-21 细胞中表达目的蛋白。在小鼠中，肌肉内接种 1×109 或 1×1010 PFU/只重组病毒可诱导产生 FMDV 特异性中和抗体和γ干扰素（IFN-γ）。此外，与不带 T 细胞表位的重组病毒相比，带有 T 细胞表位的重组病毒具有更好的免疫原性，表现为 IFN-γ产生显著增强（P<0.01）和中和抗体滴度更高（P<0.05）。尽管灭活疫苗产生的中和抗体滴度最高，但与两种重组假型杆状病毒相比，IFN-γ表达水平较低。
这些结果表明，假型杆状病毒介导的基因传递可以作为开发新一代 FMDV 感染疫苗的替代策略。
