Sun Dong, Khatun Amina, Kim Won-Il, Cooper Vickie, Cho Yong-Il, Wang Chong, Choi Eun-Jin, Yoon Kyoung-Jin
Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
College of Veterinary Medicine, Chonbuk National University, Iksan, Republic of Korea.
Vaccine. 2016 Aug 5;34(36):4335-42. doi: 10.1016/j.vaccine.2016.06.069. Epub 2016 Jul 9.
Due to significant antigenic variations between field isolates of porcine reproductive and respiratory syndrome virus (PRRSV), suboptimal cross-protection between different viruses impedes the effective control of PRRS via vaccination. Our previous study showed that chimeric viruses containing mixed structural genes from two distinct strains (VR2332 and JA142) of PRRSV were highly susceptible to the viral neutralizing activity of antisera generated against both parental strains. In this study, three chimeric viruses (JAP5, JAP56 and JAP2-6) were constructed by replacing ORF5, ORFs 5 and 6, and ORFs 2-6 of VR2332 with the corresponding genes of JA142, respectively, and their ability to confer cross-protection against challenge with the VR2332 and JA142 strains was evaluated in vivo. A total of 114 pigs were divided into 6 groups, and each group was intramuscularly injected with one of the 3 chimeric viruses (n=16 pigs per group), VR2332 (n=24), JA142 (n=24), or sham inoculum (n=18). At 44days post-inoculation (dpi), these pigs were further divided into 15 groups (n=6 or 8 pigs per group) and intranasally challenged with VR2332, JA142, or sham inoculum. All pigs inoculated with one of the chimeric viruses prior to challenge had lower viremia levels than the challenge control pigs. Prior inoculation with JAP56 markedly decreased viremia to nearly undetectable levels in pigs challenged with either VR2332 or JA142. These results suggest that chimeric viruses harboring mixed structural genes from two distinct PRRSV strains can provide protection against both donor viruses.
由于猪繁殖与呼吸综合征病毒（PRRSV）田间分离株之间存在显著的抗原变异，不同病毒之间的交叉保护效果欠佳，这阻碍了通过疫苗接种有效控制PRRS。我们之前的研究表明，含有来自PRRSV两个不同毒株（VR2332和JA142）混合结构基因的嵌合病毒，对针对两种亲本毒株产生的抗血清的病毒中和活性高度敏感。在本研究中，分别用JA142的相应基因替换VR2332的ORF5、ORF5和6以及ORF2 - 6，构建了三种嵌合病毒（JAP5、JAP56和JAP2 - 6），并在体内评估了它们对VR2332和JA142毒株攻击的交叉保护能力。总共114头猪被分为6组，每组肌肉注射三种嵌合病毒之一（每组n = 16头猪）、VR2332（n = 24）、JA142（n = 24）或假接种物（n = 18）。接种后44天（dpi），这些猪进一步分为15组（每组n = 6或8头猪），并经鼻用VR2332、JA142或假接种物攻击。在攻击前接种嵌合病毒之一的所有猪的病毒血症水平均低于攻击对照猪。预先接种JAP56可使在用VR2332或JA142攻击的猪中病毒血症显著降低至几乎检测不到的水平。这些结果表明，含有来自两种不同PRRSV毒株混合结构基因的嵌合病毒可以为两种供体病毒提供保护。
