Locke Jeffrey B, Vicknair Mike R, Ostland Vaughn E, Nizet Victor, Buchanan John T
Department of Pediatrics, Division of Pharmacology and Drug Discovery, University of California, San Diego, 9500 Gilman Drive, MC 0687, La Jolla, California 92093-0687, USA.
Dis Aquat Organ. 2010 Mar 9;89(2):117-23. doi: 10.3354/dao02192.
Streptococcus iniae poses a serious threat to finfish aquaculture operations worldwide. Stringent regulatory standards limit the use of antibiotics to treat S. iniae infections; improved vaccination strategies are thus of great interest. We investigated the potential for efficient, non-injectable batch vaccination via the use of live attenuated vaccines. Three attenuated S. iniae strains with genetic mutations eliminating the production of virulence factors--capsular polysaccharide (delta cpsD), M-like protein (delta simA), and phosphoglucomutase (delta pgmA)--were evaluated in parallel with an adjuvanted, formalin-killed, whole-cell S. iniae bacterin. Juvenile hybrid striped bass (HSB; Morone chrysops x M. saxatilis) were vaccinated through intraperitoneal (i.p.) injection or bath immersion and held for 800 degree-days prior to challenge with a lethal dose of the virulent wild-type (WT) S. iniae parent strain. The delta cpsD, delta pgmA, and bacterin vaccines provided the highest level of vaccination safety (0% mortality), whereas the delta simA mutant, although it caused 12 to 16% vaccination-related mortality, was the only vaccine candidate to provide 100% protection in both i.p. and immersion delivery models. Our studies demonstrate the efficacy of live attenuated vaccines for prevention of S. iniae infection, and identify immersion delivery of live vaccines as an attractive option for use in commercial aquaculture settings.
海豚链球菌对全球的硬骨鱼水产养殖作业构成严重威胁。严格的监管标准限制了抗生素在治疗海豚链球菌感染方面的使用；因此，改进疫苗接种策略备受关注。我们研究了通过使用减毒活疫苗进行高效、非注射式批量疫苗接种的潜力。将三株具有基因突变从而消除毒力因子——荚膜多糖（ΔcpsD）、M样蛋白（ΔsimA）和磷酸葡萄糖变位酶（ΔpgmA）——产生的减毒海豚链球菌菌株与一种佐剂化的、福尔马林灭活的全细胞海豚链球菌菌苗同时进行评估。幼年杂交条纹鲈（HSB；金眼狼鲈×条纹鲈）通过腹腔注射或浸浴进行疫苗接种，并在以致死剂量的强毒野生型（WT）海豚链球菌亲本菌株进行攻毒前饲养800度日。ΔcpsD、ΔpgmA和菌苗疫苗提供了最高水平的疫苗接种安全性（死亡率为0%），而ΔsimA突变株虽然导致了12%至16%的与疫苗接种相关的死亡率，但却是唯一在腹腔注射和浸浴接种模型中均提供100%保护的候选疫苗。我们的研究证明了减毒活疫苗预防海豚链球菌感染的有效性，并确定活疫苗的浸浴接种是商业水产养殖环境中一种有吸引力的选择。
