Aquatic Animal Health Research Unit, USDA-ARS, 990 Wire Road, Auburn, AL 36832 United States.
Vaccine. 2011 Aug 11;29(35):5986-93. doi: 10.1016/j.vaccine.2011.06.036. Epub 2011 Jun 25.
A novel attenuated Streptococcus iniae vaccine was developed from a virulent strain of Streptococcus iniae (ISET0901) through selection for novobiocin resistance (named ISNO). The safety of ISNO was then evaluated in Nile tilapia (Oreochromis niloticus) through intraperitoneal (IP) injection. When male tilapia (average weight 10 g) were IP injected with 2×10(7) colony-forming units (CFU) of the attenuated S. iniae vaccine strain, no fish died. However, when the same age and size matched tilapia were IP injected with 2×10(7) and 1×10(5)CFU of the virulent parent strain of S. iniae, 100 and 90% fish died, respectively. Backpassage safety studies revealed that ISNO was unable to revert back to a virulent state. When IP vaccinated fish were challenged by the virulent ISET0901 strain of S. iniae, relative percent survival (RPS) values of vaccinated fish at 14, 28, 60, 90, and 180 days post ISNO vaccination (dpv) were 100, 100, 100, 89, and 75%, respectively, The RPS values of ISNO vaccinated fish (IP vaccination) against infections by five heterologous virulent strains of S. iniae (F3CB, 102 F1K, 405 F1K, IF6, and ARS60) at 60 dpv were 78, 90, 100, 100, and 100%, respectively. When tilapia were IP vaccinated by ISNO at dose of 1×10(2), 1×10(3), 1×10(4), 1×10(5), 1×10(6), and 1×10(7)CFU/fish, RPS values at 28 dpv were 81, 94, 100, 100, 100, and 100%, respectively. At 28 dpv, RPS of vaccinated fish by ISNO through bath immersion (1×10(7)CFU/ml) was 88%. ELISA results revealed that protection elicited by ISNO was due to antibody- as well as cell- mediated immunity. Our results suggest that ISNO could be used as a novel safe and efficacious vaccine to protect Nile tilapia from S. iniae infections.
一种新型减毒无乳链球菌疫苗由无乳链球菌（ISET0901）通过诺氟沙星抗性选择（命名为 ISNO）研制而成。然后通过腹腔（IP）注射对尼罗罗非鱼（Oreochromis niloticus）的安全性进行评估。当雄性罗非鱼（平均体重 10 克）用 2×10（7）个菌落形成单位（CFU）的减毒链球菌疫苗株进行 IP 注射时，没有鱼死亡。然而，当相同年龄和大小匹配的罗非鱼用 2×10（7）和 1×10（5）CFU 的无乳链球菌亲株进行 IP 注射时，分别有 100%和 90%的鱼死亡。回传安全性研究表明，ISNO 无法恢复为毒力状态。当 IP 接种疫苗的鱼受到无乳链球菌 ISET0901 株的攻击时，在 ISNO 接种后 14、28、60、90 和 180 天（dpv），接种疫苗的鱼的相对存活率（RPS）值分别为 100%、100%、100%、89%和 75%。在 60 dpv 时，ISNO 接种鱼（IP 接种）对五种异源强毒力无乳链球菌菌株（F3CB、102 F1K、405 F1K、IF6 和 ARS60）的感染的 RPS 值分别为 78%、90%、100%、100%和 100%。当罗非鱼用 ISNO 以 1×10（2）、1×10（3）、1×10（4）、1×10（5）、1×10（6）和 1×10（7）CFU/鱼的剂量进行 IP 接种时，在 28 dpv 时的 RPS 值分别为 81%、94%、100%、100%、100%和 100%。在 28 dpv 时，ISNO 通过浸浴（1×10（7）CFU/ml）接种的疫苗鱼的 RPS 为 88%。ELISA 结果表明，ISNO 引起的保护作用是由抗体和细胞介导免疫引起的。我们的结果表明，ISNO 可用作一种新型安全有效的疫苗，可保护尼罗罗非鱼免受无乳链球菌感染。
