Jeong Chang-Gi, Khatun Amina, Nazki Salik, Kim Seung-Chai, Noh Yun-Hee, Kang Sang-Chul, Lee Dong-Uk, Yang Myeon-Sik, Shabir Nadeem, Yoon In-Joong, Kim Bumseok, Kim Won-Il
College of Veterinary Medicine, Jeonbuk National University, Iksan 54596, Korea.
Department of Pathology, Faculty of Animal Science and Veterinary Medicine, Sher-e-Bangla Agricultural University, Dhaka 1207, Bangladesh.
Vaccines (Basel). 2021 Oct 31;9(11):1258. doi: 10.3390/vaccines9111258.
Despite the routine use of porcine reproductive and respiratory syndrome (PRRS)-modified live vaccines, serious concerns are currently being raised due to their quick reversion to virulence and limited cross-protection against divergent PRRS virus (PRRSV) strains circulating in the field. Therefore, a PRRS chimeric vaccine (JB1) was produced using a DNA-launched infectious clone by replacing open reading frames (ORFs) 3-6 with those from a mixture of two genetically different PRRSV2 strains (K07-2273 and K08-1054) and ORF1a with that from a mutation-resistant PRRSV strain (RVRp22) exhibiting an attenuated phenotype. To evaluate the safety and cross-protective efficacy of JB1 in a reproductive model, eight PRRS-negative pregnant sows were purchased and divided into four groups. Four sows in two of the groups were vaccinated with JB1, and the other 4 sows were untreated at gestational day 60. At gestational day 93, one vaccinated group and one nonvaccinated group each were challenged with either K07-2273 or K08-1054. All of the sows aborted or delivered until gestation day 115 (24 days post challenge), and the newborn piglets were observed up to the 28th day after birth, which was the end of the experiment. Overall, pregnant sows of the JB1-vaccinated groups showed no meaningful viremia after vaccination and significant reductions in viremia with K07-2273 and K08-1054, exhibiting significantly higher levels of serum virus-neutralizing antibodies than non-vaccinated sows. Moreover, the JB1-vaccinated groups did not exhibit any abortion due to vaccination and showed improved piglet viability and birth weight. The piglets from JB1-vaccinated sows displayed lower viral concentrations in serum and fewer lung lesions compared with those of the piglets from the nonvaccinated sows. Therefore, JB1 is a safe and effective vaccine candidate that confers simultaneous protection against two genetically different PRRSV strains.
尽管猪繁殖与呼吸综合征（PRRS）- 活疫苗已常规使用，但由于其迅速返强以及对田间流行的不同PRRS病毒（PRRSV）毒株交叉保护有限，目前引发了严重担忧。因此，通过DNA启动的感染性克隆制备了一种PRRS嵌合疫苗（JB1），用来自两种基因不同的PRRSV2毒株（K07 - 2273和K08 - 1054）混合物的开放阅读框（ORF）3 - 6替换，并用来自表现出减毒表型的抗突变PRRSV毒株（RVRp22）的ORF1a替换。为了评估JB1在繁殖模型中的安全性和交叉保护效力，购买了8头PRRS阴性的怀孕母猪并分为四组。两组中的4头母猪在妊娠第60天接种JB1，另外4头母猪未处理。在妊娠第93天，一个接种组和一个未接种组分别用K07 - 2273或K08 - 1054进行攻毒。所有母猪均流产或分娩至妊娠第115天（攻毒后24天），并对新生仔猪观察至出生后第28天，即实验结束。总体而言，接种JB1组的怀孕母猪接种后未出现有意义的病毒血症，用K07 - 2273和K08 - 1054攻毒后病毒血症显著降低，血清病毒中和抗体水平显著高于未接种母猪。此外，接种JB1组未因接种出现任何流产，仔猪活力和出生体重有所改善。与未接种母猪的仔猪相比，接种JB1母猪的仔猪血清中病毒浓度较低，肺部病变较少。因此，JB1是一种安全有效的候选疫苗，可同时对两种基因不同的PRRSV毒株提供保护。
