Zhang Yanping, Liu Changjun, Yan Fuhai, Liu Ailing, Cheng Yun, Li Zhijie, Sun Guorong, Lv Hongchao, Wang Xiaomei
Avian Immunosuppressive Diseases Division, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, PR China.
Avian Immunosuppressive Diseases Division, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, PR China.
Vaccine. 2017 Aug 24;35(36):4695-4701. doi: 10.1016/j.vaccine.2017.07.048. Epub 2017 Jul 25.
Gallid herpesvirus 2 (GaHV-2) continuously evolves, which reduces the effectiveness of existing vaccines. To construct new GaHV-2 candidate vaccines, LMS, which is a virulent GaHV-2 field strain isolated from diseased chicken flocks in Southwest China in 2007, was modified such that both copies of its meq oncogene were partially deleted. The resulting virus, i.e., rMSΔmeq, was characterized using PCR and sequencing. To evaluate the safety and protective efficacy of rMSΔmeq, specific pathogen-free (SPF) chickens were inoculated with 2000 plaque forming units (pfu) and 20,000pfu of rMSΔmeq immediately after hatching. All birds grew well during the experimental period, and none of the challenged chickens developed Marek's disease-associated lymphoma. In addition, the rMSΔmeq- and CVI988/Rispens-vaccinated SPF chickens were challenged with 1000 pfu and 5000 pfu of the representative virulent GaHV-2 Md5 strain and 1000 pfu of the variant GaHV-2 strains LCC or LTS. The results showed that the rMSΔmeq strain provided complete protection, which was similar to that provided by the CVI988/Rispens vaccine (protective index (PI) of 95.5) when challenged with a conventional dose of the Md5 strain. However, rMSΔmeq provided a PI of 90.9 when challenged with 5000 pfu of the Md5 strain, which was significantly higher than that provided by the CVI988/Rispens vaccine (54.5). rMSΔmeq provided a PI of 86.4 against LCC, which was equal to that provided by the CVI988/Rispens vaccine (81.8). In addition, rMSΔmeq provided a PI of 100 against LTS, which was significantly higher than that provided by the CVI988/Rispens vaccine (68.2). Altogether, the rMSΔmeq virus provided efficient protection against representative and variant GaHV-2 strains. In conclusion, the rMSΔmeq virus is a safe and effective vaccine candidate for the prevention of Marek's disease and is effective against the Chinese variant GaHV-2 strains.
鸡疱疹病毒2型（GaHV - 2）不断进化，这降低了现有疫苗的效力。为构建新型GaHV - 2候选疫苗，对LMS（2007年从中国西南部患病鸡群中分离出的一种强毒GaHV - 2野毒株）进行改造，使其meq癌基因的两个拷贝都被部分缺失。利用聚合酶链反应（PCR）和测序对得到的病毒rMSΔmeq进行了特性分析。为评估rMSΔmeq的安全性和保护效力，在特定病原体-free（SPF）鸡孵化后立即用2000个空斑形成单位（pfu）和20000 pfu的rMSΔmeq进行接种。在实验期间所有鸡生长良好，且所有受攻毒的鸡均未发生马立克氏病相关淋巴瘤。此外，用1000 pfu和5000 pfu的代表性强毒GaHV - 2 Md5株以及1000 pfu的变异GaHV - 2株LCC或LTS对接种rMSΔmeq和CVI988/Rispens疫苗的SPF鸡进行攻毒。结果显示，当用常规剂量的Md5株攻毒时，rMSΔmeq株提供了完全保护，这与CVI988/Rispens疫苗提供的保护相似（保护指数（PI）为95.5）。然而，当用5000 pfu的Md5株攻毒时，rMSΔmeq的PI为90.9，显著高于CVI988/Rispens疫苗（54.5）。rMSΔmeq对LCC的PI为86.4，与CVI988/Rispens疫苗提供的保护相当（81.8）。此外，rMSΔmeq对LTS的PI为100，显著高于CVI988/Rispens疫苗（68.2）。总之，rMSΔmeq病毒对代表性和变异GaHV - 2株提供了有效的保护。综上所述，rMSΔmeq病毒是预防马立克氏病的一种安全有效的候选疫苗，并且对中国变异GaHV - 2株有效。
