Hussein Mortada M A, Hassan Walid H, Yassen Hosam A, Osman Ahmed M A
Fish Diseases and Management Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, 62513, Egypt.
Bacteriology, Mycology and Immunology Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, 62513, Egypt.
Fish Shellfish Immunol. 2023 Oct;141:109008. doi: 10.1016/j.fsi.2023.109008. Epub 2023 Aug 19.
Streptococcosis is an important bacterial disease affects fresh, brackish and marine fish. The disease caused annual severe economic losses in Egyptian Mari-culture. S. iniae and L. garvieae usually the main causative agents isolated. The presented study conducted to prepare bacterial ghost vaccine (BGV) candidates from isolated strains of marine streptococcosis outbreaks using NaOH chemical approach. Selected strains confirmed as pathogenic for Nile tilapia, therefore the fish selected as an experimental model. In such respect, the re-isolated S. iniae and L. garvieae were used for ghost preparations, BGVs evaluation and fish challenges. Apart of four, three fish groups namely, A, B, C designated for BGVs evaluations, while the fourth one (D) designated as control. Vaccination experiments performed via intra-peritoneal injection with 0.1 mL (1.5 × 10 CFU/mL/fish) of their corresponding BGVs twice with 2 weeks' interval; however, control fish received 0.1 mL of fish saline instead. Blood, serum, and tissue samples collected from all groups at 2 and 4 weeks post immunization (PI) for estimation of hematological, innate, and specific immune parameters. At the end, all remained fish challenged with appropriated pathogen (s) and the relative percentage of survival (RPS) calculated. Three BGVs generated namely, SiG, in addition to, novel contributions of LgG and SiLgG. Ghosts were corresponding to S. iniae, L. garvieae and their both ghost mixtures, respectively. Fish groups immunized with prepared BGVs revealed variable significant increases in PCV, GLB, PP, SOD, CAT, C5, IL-β1, LZM, specific antibody titers and CD4 expression 2 and 4 weeks PI. MDA decreased in all vaccinated groups that was significantly with group C. Expression of MHC-II showed elevations 2 weeks PI, however, it significantly decreased at 4 weeks. The RPS recorded 90, 88.89 and 95.46% in immunized groups A, B and C, respectively. At all levels tested, obtained results proposed SiG, LgG and SiLgG as innovative vaccine candidates, which can protect cultured fish from being attacked by S. iniae, and/or L. garvieae.
链球菌病是一种影响淡水、咸淡水和海水鱼类的重要细菌性疾病。该病在埃及海水养殖中每年造成严重的经济损失。海豚链球菌和加氏乳球菌通常是分离出的主要病原体。本研究采用氢氧化钠化学方法，从海洋链球菌病暴发的分离菌株中制备细菌幽灵疫苗（BGV）候选物。选定的菌株被确认为对尼罗罗非鱼具有致病性，因此选择该鱼作为实验模型。在这方面，重新分离的海豚链球菌和加氏乳球菌用于制备幽灵、评估BGV和对鱼进行攻毒试验。除了四组鱼外，将三组鱼分别命名为A、B、C组用于评估BGV，而第四组（D组）作为对照组。通过腹腔注射0.1 mL（1.5×10 CFU/mL/鱼）相应的BGV进行疫苗接种实验，间隔2周注射两次；然而，对照鱼注射0.1 mL鱼生理盐水。在免疫后（PI）2周和4周从所有组采集血液、血清和组织样本，以评估血液学、先天性和特异性免疫参数。最后，用相应病原体对所有剩余的鱼进行攻毒，并计算相对存活率（RPS）。制备了三种BGV，即SiG，此外还有新型的LgG和SiLgG。幽灵分别对应海豚链球菌、加氏乳球菌及其两者的幽灵混合物。用制备的BGV免疫的鱼组在免疫后2周和4周时，红细胞压积（PCV）、球蛋白（GLB）、血小板（PP）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、补体5（C5）、白细胞介素-β1（IL-β1）、溶菌酶（LZM）、特异性抗体滴度和CD4表达均有不同程度的显著增加。所有接种组的丙二醛（MDA）均下降，C组下降显著。主要组织相容性复合体II类（MHC-II）的表达在免疫后2周升高，但在4周时显著下降。免疫组A、B和C的RPS分别为90%、88.89%和95.46%。在所有测试水平上，获得的结果表明SiG、LgG和SiLgG是创新的疫苗候选物，可保护养殖鱼类免受海豚链球菌和/或加氏乳球菌的攻击。
