Laboratory of Aquatic Organisms Pathology (Lapoa), Aquaculture Center from UNESP (CAUNESP), Rodovia de Acesso Paulo Donato Castellane s/n, CEP 14884-900, Jaboticabal, SP, Brazil.
Department of Microbiology, Faculty of Sciences, University of Malaga, 29071, Malaga, Spain.
Fish Shellfish Immunol. 2020 Jun;101:186-191. doi: 10.1016/j.fsi.2020.03.059. Epub 2020 Apr 1.
Aeromonas hydrophila is responsible for outbreaks of a severe infectious disease in fish farms around the world and is one of the major causes of economic losses to the neotropical fish farmers. This study assessed the induction of immune responses and protection against A. hydrophila in pacu, Piaractus mesopotamicus, vaccinated through intraperitoneal and immersion route with inactivated virulent strain. Fish were randomly distributed in three vaccinated groups: intraperitoneal (i.p.) route; immersion; and immersion + booster; and control group (unvaccinated). All vaccination protocols used the concentration of 1.7 × 10 CFU mL of inactivated A. hydrophila., and an oil adjuvant was used for vaccine prepararion for i.p. route vaccination. Blood and skin mucus from 9 fishes per treatment were collected at 14, 28, 42 and 84 days post-vaccination (DPV) for determination of lysozyme concentration in skin mucus, as well as antibodies anti-A. hydrophila in blood serum and skin mucus. Fish were challenged at 84 DPV with homologous and virulent strain of A. hydrophila for evaluation of resistance against bacterial infection. The results demonstrated that vaccination with inactivated A. hydrophila suspension by i.p. or immersion resulted in significant increase of skin mucus lysozyme and specific antibody levels in serum and skin mucus, at 28 and 42 DPV, and this increase in innate and adaptive immunity remained significant in pacu vaccinated through i.p. route up to 84 DPV. Although no significant differences were observed in the survival study, pacu vaccinated through i.p. route presented 31,33% of relative percentage survival (RPS) in LD when compared unvaccinated fish challenged at 84 DPV. The results observed in this study indicate that vaccination programs with inactivated A. hydrophila, including booster doses by i.p. or immersion routes, could result in more effective protection in pacu against this bacteriosis, by increasing innate and adaptive mucosal and systemic immune responses.
嗜水气单胞菌是导致世界范围内鱼类养殖场爆发严重传染病的原因之一，也是新热带地区鱼类养殖户经济损失的主要原因之一。本研究评估了通过腹腔内和浸泡途径用灭活的强毒菌株对巨臀脂鲤（Piaractus mesopotamicus）进行免疫接种，诱导免疫反应和预防嗜水气单胞菌感染的效果。鱼被随机分配到三个接种组：腹腔内（i.p.）途径；浸泡；浸泡+加强针；和对照组（未接种）。所有疫苗接种方案均使用浓度为 1.7×10 CFU mL 的灭活嗜水气单胞菌，并且油佐剂用于 i.p.途径接种的疫苗制备。在接种后 14、28、42 和 84 天（DPV），从每个处理的 9 条鱼中采集血液和皮肤黏液，以测定皮肤黏液中的溶菌酶浓度，以及血清和皮肤黏液中的抗嗜水气单胞菌抗体。在 84 DPV 时，用同源和强毒的嗜水气单胞菌对鱼进行攻毒，以评估对细菌感染的抵抗力。结果表明，通过腹腔内或浸泡途径接种灭活的嗜水气单胞菌悬液可导致皮肤黏液中溶菌酶和血清及皮肤黏液中特异性抗体水平在 28 和 42 DPV 时显著增加，这种先天和适应性免疫的增加在通过腹腔内途径接种的巨臀脂鲤中一直持续到 84 DPV。尽管在生存研究中没有观察到显著差异，但在 84 DPV 时，与未接种的鱼相比，通过腹腔内途径接种的鱼的相对存活率（RPS）为 31.33%。本研究的结果表明，包括通过腹腔内或浸泡途径进行加强针免疫接种在内的灭活嗜水气单胞菌疫苗接种方案，可通过增加先天和适应性黏膜和全身免疫反应，更有效地保护巨臀脂鲤免受这种细菌性疾病的侵害。
