Sudheesh Ponnerassery S, Cain Kenneth D
Department of Fish and Wildlife Sciences and Aquaculture Research Institute, College of Natural Resources, University of Idaho, Moscow, ID 83844-1136, USA.
Department of Fish and Wildlife Sciences and Aquaculture Research Institute, College of Natural Resources, University of Idaho, Moscow, ID 83844-1136, USA.
Fish Shellfish Immunol. 2016 Sep;56:169-180. doi: 10.1016/j.fsi.2016.07.004. Epub 2016 Jul 9.
This study was aimed at optimizing the efficacy of a recently developed live attenuated immersion vaccine (B.17-ILM) as a promising vaccine against bacterial coldwater disease (BCWD) caused by Flavobacterium psychrophilum in salmonids. Rainbow trout (RBT) fry were vaccinated by immersion, and different parameters affecting vaccination such as fish size, vaccine delivery time, dose, duration of protection, booster regimes and vaccine growth incubation time were optimized. Specific anti-F. psychrophilum immune response was determined by ELISA. Protective efficacy was determined by challenging with a virulent strain of F. psychrophilum (CSF-259-93) and calculating cumulative percent mortality (CPM) and relative percent survival (RPS). All vaccinated fish developed significantly higher levels of serum antibody titers by week 8 when compared to their respective controls. Immersion vaccination for 3, 6 and 30 min produced significant protection with comparable RPS values of 47%, 53% and 52%, respectively. This vaccine provided significant protection for fish as small as 0.5 g with an RPS of 55%; larger fish of 1 g and 2 g yielded slightly higher RPS values of 59% and 60%, respectively. Fish vaccinated with higher vaccine doses of ∼10(10) and 10(8) colony forming units mL(-1) (cfu ml(-1)) were strongly protected out to at least 24 weeks with RPS values up to 70%. Fish vaccinated with lower doses (∼10(6) and 10(5) cfu mL(-1)) had good protection out to 12 weeks, but RPS values dropped to 36% and 34%, respectively by 24 weeks. Vaccine efficacy was optimum when the primary vaccination was followed by a single booster (week 12 challenge RPS = 61%) rather than two boosters (week 12 challenge RPS = 48%). Vaccination without a booster resulted in a lower RPS (13%) indicating the necessity of a single booster vaccination to maximize efficacy. This study presents key findings that demonstrate the efficacy and commercial potential for this live attenuated BCWD vaccine.
本研究旨在优化一种最近开发的减毒活浸浴疫苗（B.17-ILM）的效力，该疫苗有望用于预防鲑科鱼类由嗜冷黄杆菌引起的细菌性冷水病（BCWD）。虹鳟鱼苗通过浸浴进行疫苗接种，并对影响疫苗接种的不同参数进行了优化，如鱼的大小、疫苗接种时间、剂量、保护期、加强免疫方案以及疫苗生长培养时间。通过酶联免疫吸附测定（ELISA）确定特异性抗嗜冷黄杆菌免疫反应。通过用嗜冷黄杆菌强毒株（CSF-259-93）进行攻毒，并计算累积死亡率（CPM）和相对存活率（RPS）来确定保护效力。与各自的对照组相比，所有接种疫苗的鱼在第8周时血清抗体滴度水平显著更高。浸浴接种3、6和30分钟均产生了显著的保护作用，RPS值分别为47%、53%和52%，具有可比性。这种疫苗对小至0.5克的鱼提供了显著保护，RPS为55%；1克和2克的较大鱼的RPS值略高，分别为59%和60%。接种剂量约为10¹⁰和10⁸菌落形成单位/毫升（cfu/ml）的较高疫苗剂量的鱼受到了强烈保护，至少在24周内RPS值高达70%。接种较低剂量（约10⁶和10⁵ cfu/ml）的鱼在12周内具有良好的保护作用，但到24周时RPS值分别降至36%和34%。当首次接种后进行一次加强免疫时疫苗效力最佳（第12周攻毒RPS = 61%），而不是两次加强免疫（第12周攻毒RPS = 48%）。不进行加强免疫的接种导致较低的RPS（13%），表明需要进行一次加强免疫以最大化效力。本研究提出了关键发现，证明了这种减毒活BCWD疫苗的效力和商业潜力。
