Zhu Xuejiao, Liu Jie, Bai Juan, Liu Panrao, Zhang Tingjie, Jiang Ping, Wang Xianwei
Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.
J Virol Methods. 2016 Apr;230:36-44. doi: 10.1016/j.jviromet.2016.01.011. Epub 2016 Jan 27.
Porcine circovirus type 2 (PCV2) causes significant economic losses to the swine industry worldwide. Heat shock proteins (Hsps) can be used as modulators to enhance both innate and adaptive immune responses. In the present study, recombinant baculoviruses expressing the PCV2Cap protein and the N-terminal 22-370 amino acids of porcine Gp96 (Gp96N), Hsp90, and Hsp70 (rBac-cap/Gp96N, rBac-cap/Hsp90 and rBac-cap/Hsp70, respectively) were constructed and the immune responses were examined in mice and piglets. The mouse experiments showed that rBac-cap/Gp96N increased the titers of specific anti-PCV2 neutralizing antibodies, proliferative responses of peripheral blood mononuclear cells (PBMCs) and IFN-γ levels compared to rBac-cap/Hsp90, rBac-cap/Hsp70, or rBac-cap. The pig experiments showed that the levels of anti-PCV2 antibody, proliferative responses of PBMCs, and IFN-γ in the rBac-cap/Gp96N groups were increased compared to those in rBac-cap group. There were no clear clinical signs of infection following PCV2 challenge in pigs inoculated with recombinant rBac-cap/Gp96N and rBac-cap, and the relative daily weight gains were higher than those in the challenge control (CC) group. The pathological lesions, extent of viremia, and viral loads of the vaccinated groups were milder than those in the CC group. Meanwhile, the extent of viremia and viral load present in the rBac-cap/Gp96N group were significantly lower than those in the rBac-cap group. These results indicated that porcine Gp96N effectively increased the humoral and cell-mediated immune responses of PCV2Cap. Gp96N presents an attractive adjuvant or immunotargeting strategy to enhance the protective efficacy of PCV2 subunit vaccines in swine.
猪圆环病毒2型（PCV2）给全球养猪业造成了巨大的经济损失。热休克蛋白（Hsps）可用作调节剂，以增强先天性和适应性免疫反应。在本研究中，构建了表达PCV2Cap蛋白以及猪Gp96的N端22 - 370个氨基酸（Gp96N）、Hsp90和Hsp70的重组杆状病毒（分别为rBac-cap/Gp96N、rBac-cap/Hsp90和rBac-cap/Hsp70），并在小鼠和仔猪中检测免疫反应。小鼠实验表明，与rBac-cap/Hsp90、rBac-cap/Hsp70或rBac-cap相比，rBac-cap/Gp96N增加了特异性抗PCV2中和抗体的滴度、外周血单个核细胞（PBMCs）的增殖反应以及IFN-γ水平。猪实验表明，与rBac-cap组相比，rBac-cap/Gp96N组的抗PCV2抗体水平、PBMCs的增殖反应以及IFN-γ水平均有所增加。用重组rBac-cap/Gp96N和rBac-cap接种的猪在受到PCV2攻击后没有明显的感染临床症状，且相对日增重高于攻击对照组（CC）。接种组的病理损伤、病毒血症程度和病毒载量均比CC组轻。同时，rBac-cap/Gp96N组的病毒血症程度和病毒载量明显低于rBac-cap组。这些结果表明，猪Gp96N有效增强了PCV2Cap的体液免疫和细胞介导免疫反应。Gp96N为增强猪PCV2亚单位疫苗的保护效力提供了一种有吸引力的佐剂或免疫靶向策略。
