Assessment of the Safety and Efficacy of an Attenuated Live Vaccine Based on Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus

作者：Yu Xiuling; Zhou Zhi; Cao Zhen; Wu Jiajun; Zhang Zhongqiu; Xu Baiwan; Wang Chuanbin; Hu Dongmei; Deng Xiaoyu; Han Wei; Gu Xiaoxue; Zhang Shuo; Li Xiaoxia; Wang Baoyue; Zhai Xinyan^*; Tian Kegong

来源：Clinical and Vaccine Immunology, 2015, 22(5): 493-502.

DOI：10.1128/CVI.00722-14

The safety and efficacy of the JXA1-R vaccine, an attenuated strain of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV), were examined using an intramuscular challenge model in piglets. The JXA1-R vaccine was obtained by passing HP-PRRSV JXA1 through Marc-145 cells (82nd passage). Genomic sequence comparisons showed that strain JXA1-R and its parental strain, JXA1, differ by 47 amino acids, and most of these differences are scattered throughout the PRRSV genome. Four-week-old PRRSV-free piglets were inoculated intramuscularly with JXA1-R vaccine (10(3.0), 10(4.0), 10(5.0), 10(6.0), and 10(7.0) 50% tissue culture infective doses [ TCID50]/ml for groups 1 to 5, respectively) and then challenged intramuscularly with the 5th passage virus of JXA1 virus (JXA1-F5, 3 ml x 10(4.5) TCID50/ml) 28 days after inoculation. The humoral immune response, swine growth, clinical signs, and differential organ lesions were monitored. The results showed that all vaccinated piglets had a perceptible humoral immune response to vaccination after day 7, which then promptly increased, almost reaching the maximum sample/positive (S/P) ratio value at 28 days postimmunization. Viremia detection indicated that the viral replication levels of the challenge virus in the immunized groups (immunization doses >= 10(4.0)/ml) were significantly lower than that of the virus-challenged unvaccinated control group. Piglets in groups 2 to 5 were effectively protected against lethal HP-PRRSV infection and did not show any obvious changes in body temperature or clinical signs of disease at any point during the experiment. However, two of five piglets in group 1 showed mild pathological lesions and transitory high fever. These results suggest that JXA1-R (TCID50/ml >= 10(4.0)) is sufficiently attenuated and can provide effective protection against the lethal wild-type HP-PRRSV.

• 出版日期2015-5
• 单位中国动物疫病预防控制中心