University of Veterinary and Animal Sciences, Department of Fisheries and Aquaculture, Lahore, Pakistan.
University of Veterinary and Animal Sciences, Quality Operations Laboratory, Lahore, Pakistan.
Braz J Biol. 2021 Sep 20;83:e249913. doi: 10.1590/1519-6984.249913. eCollection 2021.
Aeromonas hydrophila is a cause of infectious disease outbreaks in carp species cultured in South Asian countries including Pakistan. This bacterium has gained resistance to a wide range of antibiotics and robust preventive measures are necessary to control its spread. No prior use of fish vaccines has been reported in Pakistan. The present study aims to develop and evaluate inactivated vaccines against local strain of A. hydrophila in Pakistan with alum-precipitate as adjuvant. The immunogenic potential of vaccine was evaluated in two Indian major carps (Rohu: Labeo rohita, Mori: Cirrhinus mrigala) and a Chinese carp (Grass carp: Ctenopharyngodon idella). Fish were vaccinated intraperitoneally followed by a challenge through immersion. Fish with an average age of 4-5 months were randomly distributed in three vaccinated groups with three vaccine concentrations of 108, 109 and 1010 colony forming unit (CFU)/ml and a control group. Fixed dose of 0.1ml was applied to each fish on 1st day and a booster dose at 15 days post-vaccination (DPV). Blood samples were collected on 14, 28, 35, 48 and 60 DPV to determine antibody titers in blood serum using compliment fixation test (CFT). Fish were challenged at 60 DPV with infectious A. hydrophila with 108 CFU/ml through immersion. Significantly higher levels of antibody titers were observed from 28 DPV in all vaccinated groups as compared to those in the control group. In challenge experiment the average RPS (relative percent survivability) was 71% for groups vaccinated with 109 and 1010 CFU/ml and 86% for 108 CFU/ml. Vaccine with 108 CFU/ml induced highest immune response followed by 109 and 1010 CFU/ml. The immune response of L. rohita and C. idella was better than that of C. mrigala. In general, normal histopathology was observed in different organs of vaccinated fish whereas minor deteriorative changes were found in fish vaccinated with higher concentrations of the vaccine.
嗜水气单胞菌是南亚国家（包括巴基斯坦）养殖鲤鱼种传染病暴发的原因。这种细菌已经对多种抗生素产生了耐药性，因此需要采取强有力的预防措施来控制其传播。在巴基斯坦，以前没有使用过鱼类疫苗。本研究旨在开发和评估巴基斯坦当地嗜水气单胞菌的灭活疫苗，并使用明矾沉淀作为佐剂。在两种印度主要鲤鱼（罗非鱼：Labeo rohita，Mori：Cirrhinus mrigala）和一种中国鲤鱼（草鱼：Ctenopharyngodon idella）中评估了疫苗的免疫原性。鱼通过腹腔内接种疫苗，然后通过浸泡进行挑战。平均年龄为 4-5 个月的鱼被随机分配到三个接种组，每个组有三个疫苗浓度（108、109 和 1010 个菌落形成单位（CFU）/ml）和一个对照组。第 1 天，每条鱼应用固定剂量为 0.1ml，在接种疫苗后 15 天（DPV）进行加强剂量。在 14、28、35、48 和 60 DPV 时采集血液样本，使用补体固定试验（CFT）测定血清中的抗体滴度。在 60 DPV 时，通过浸泡用 108 CFU/ml 的传染性嗜水气单胞菌对鱼进行挑战。与对照组相比，所有接种组从 28 DPV 开始观察到抗体滴度显著升高。在挑战实验中，109 和 1010 CFU/ml 组的平均 RPS（相对存活率）为 71%，108 CFU/ml 组为 86%。108 CFU/ml 组诱导的疫苗产生了最高的免疫反应，其次是 109 和 1010 CFU/ml 组。罗非鱼和草鱼的免疫反应优于鲤鱼。一般来说，在接种疫苗的鱼的不同器官中观察到正常的组织病理学，而在接种高浓度疫苗的鱼中发现了轻微的恶化变化。
