Farmacología en Aquacultura Veterinaria FAV S.A., Investigación y Desarrollo, Santiago, Chile.
Farmacología en Aquacultura Veterinaria FAV S.A., Laboratorio de Investigación y Desarrollo, Puerto Varas, Chile.
J Fish Dis. 2023 Oct;46(10):1085-1096. doi: 10.1111/jfd.13828. Epub 2023 Jun 25.
Flavobacterium psychrophilum is a pathogenic bacterium affecting Chilean salmonid farms. High antigenic and genetic diversity exists among Chilean F. psychrophilum isolates, but the distribution thereof among farms is poorly understood. These epidemiological data are key for developing isolate-specific vaccines. The present study isolated F. psychrophilum in diseased Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) from five freshwater farms between 2018 and 2019. Each farm only raised one salmonid species and was geographically separated from and did not share culturing water with the other farms. Antigenic and genetic analyses were conducted to shed light on the possibility of isolates coexisting within the same farm during outbreaks. A total of 68 Chilean F. psychrophilum isolates were recovered from skin lesions, gills, fins, kidney and spleen of moribund and live fish. Among the 68 Chilean isolates, mPCR-serotyping indicated three major serotypes (i.e. 23.5% type 0; 47.1% type 2; and 26.5% type 4) and, to a lesser degree, serotype 1 (2.9%). Sixteen antigenic groups were detected by slide agglutination. Genetic characterizations by 16S rRNA alleles identified 71% of the isolates as the virulent genogroup CSF259-93 allele. A predominant serotype was associated with each farm, with types 0 and 4 related to Atlantic salmon and types 1 and 2 to rainbow trout. Notwithstanding, several antigenic groups coexisted within some farms. Likewise, the experimental intramuscular challenges (n = 20) demonstrated that the type-2 isolates from rainbow trout were the most pathogenic among isolates recovered from infectious outbreaks in Atlantic salmon, especially as compared to those from types-0 and -4. These results allow us to suggest that prevention measures, specifically vaccines, should be developed according to dominant isolates and with specificity to each farm, that is the use of autogenous or site-specific vaccines.
嗜冷杆菌是一种影响智利鲑鱼养殖场的致病性细菌。智利嗜冷杆菌分离株存在高度的抗原和遗传多样性，但对其在养殖场之间的分布情况了解甚少。这些流行病学数据对于开发分离株特异性疫苗至关重要。本研究于 2018 年至 2019 年期间从五个淡水养殖场的患病大西洋鲑（Salmo salar）和虹鳟（Oncorhynchus mykiss）中分离出嗜冷杆菌。每个养殖场只养殖一种鲑鱼，且在地理位置上与其他养殖场分开，不共用养殖用水。进行抗原和遗传分析，以了解在疫情爆发期间同一养殖场内分离株共存的可能性。从濒死和活鱼的皮肤损伤、鳃、鳍、肾脏和脾脏中总共回收了 68 株智利嗜冷杆菌分离株。在 68 株智利分离株中，mPCR 血清分型表明存在三种主要血清型（即 23.5%的 0 型；47.1%的 2 型；26.5%的 4 型），程度较小的为 1 型（2.9%）。通过玻片凝集检测到 16 个抗原群。通过 16S rRNA 等位基因进行的遗传特征分析表明，71%的分离株为毒力基因群 CSF259-93 等位基因。每个养殖场都与一种主要血清型相关，0 型和 4 型与大西洋鲑有关，1 型和 2 型与虹鳟有关。尽管如此，在一些养殖场内仍存在多个抗原群共存的情况。同样，实验性肌肉内挑战（n=20）表明，来自虹鳟的 2 型分离株在从大西洋鲑传染性疫情中回收的分离株中是最具致病性的，尤其是与 0 型和 4 型相比。这些结果表明，应根据优势分离株并针对每个养殖场制定预防措施，特别是疫苗，即使用同源或特定部位疫苗。
