Li Yafei, Li Junhui, He Sun, Zhang Wei, Cao Jian, Pan Xiaomei, Tang Huifen, Zhou En-Min, Wu Chunyan, Nan Yuchen
Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China.
Scientific Observing and Experimental Station of Veterinary Pharmacology and Veterinary Biotechnology, Ministry of Agriculture, Yangling 712100, China.
Vaccines (Basel). 2020 Aug 31;8(3):490. doi: 10.3390/vaccines8030490.
Although widespread administration of attenuated porcine reproductive and respiratory syndrome virus (PRRSV) vaccines has been implemented since they first became commercially available two decades ago, PRRSV infection prevalence in swine herds remains high. The limited success of PRRSV vaccines is partly due to the well-established fact that a given vaccine strain confers only partial or no protection against heterologous strains. In our past work, A2MC2-P90, a novel PRRSV vaccine candidate that induced a type I IFNs response in vitro, conferred complete protection against challenge with genetically heterologous PRRSV strains. Here we assessed the ability of the PRRSV vaccine candidate A2MC2-P90 to protect piglets against the HP-PRRSV challenge and compared its efficacy to that of a licensed HP-PRRSV-specific vaccine (TJM-F92) assessed in parallel. A2MC2-P90 provided vaccinated piglets with 100% protection from a lethal challenge with extremely virulent HP-PRRSV-XJA1, while 100% mortality was observed for unvaccinated piglets by day 21 post-challenge. Notably, comparison of partial sequence (GP5) of XJA1 to A2MC2-P90 suggested there was only 88.7% homology. When comparing post-HP-PRRSV challenge responses between piglets administered A2AMC2-P90 versus those immunized with licensed vaccine TJM-F92, A2MC2-P90-vaccinated piglets rapidly developed a stronger protective humoral immune response, as evidenced by much higher titers of neutralizing antibodies, more rapid clearance of viremia and less nasal virus shedding. In conclusion, our data suggest that this novel vaccine candidate A2MC2-P90 has improved protection spectrum against heterologous HP-PRRSV strains.
尽管自二十年前减毒猪繁殖与呼吸综合征病毒（PRRSV）疫苗首次上市以来已广泛应用，但猪群中PRRSV感染率仍然很高。PRRSV疫苗效果有限，部分原因是一个既定事实，即给定的疫苗株对异源毒株仅提供部分保护或无保护作用。在我们过去的研究中，新型PRRSV疫苗候选株A2MC2-P90在体外可诱导I型干扰素反应，对基因异源的PRRSV毒株攻击提供完全保护。在此，我们评估了PRRSV疫苗候选株A2MC2-P90保护仔猪抵抗高致病性PRRSV（HP-PRRSV）攻击的能力，并将其效果与同时评估的一种已获许可的HP-PRRSV特异性疫苗（TJM-F92）进行比较。A2MC2-P90为接种疫苗的仔猪提供了100%保护，使其免受高致病性HP-PRRSV-XJA1致死性攻击，而未接种疫苗的仔猪在攻击后第21天观察到100%死亡率。值得注意的是，XJA1与A2MC2-P90的部分序列（GP5）比较显示同源性仅为88.7%。当比较接种A2MC2-P90的仔猪与接种已获许可疫苗TJM-F92的仔猪在HP-PRRSV攻击后的反应时，接种A2MC2-P90的仔猪迅速产生更强的保护性体液免疫反应，表现为中和抗体滴度高得多、病毒血症清除更快以及鼻腔病毒排出更少。总之，我们的数据表明，这种新型疫苗候选株A2MC2-P90对异源HP-PRRSV毒株具有更宽的保护谱。
