Effect of Piscirickettsia salmonis inoculation on the ASK continuous cell line

Piscirickettsiosis, caused by the intracellular Gram‐negative bacteria Piscirickettsia salmonis, is at present the most devastating disease in the Chilean salmon industry. The aim of this study was to analyse disease development after challenge with a P. salmonis strain (EM90‐like) under a controlled environment by comparing intraperitoneal challenge with cohabitation challenge. The P. salmonis EM90‐like isolate was cultured in a liquid medium for the challenge of 400 Atlantic salmon (Salmo salar) smolts. Cumulative mortality was registered, necropsy was performed, and bacterial distribution in the tissues and histopathological changes were analysed. The results revealed a similar progression of the disease for the two different challenge models. Pathological and histopathological changes became more visible during the development of the clinical phase of the disease. Bacterial DNA was identified in all the analysed tissues indicating a systemic infection. Bacterial tropism to visceral organs was demonstrated by real‐time quantitative PCR and immunohistochemistry. Better knowledge of disease development during P. salmonis infection may contribute to further development of challenge models that mimic the field situation during piscirickettsiosis outbreaks. The models can be used to develop and test future preventive measures against the disease.

Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Development of piscirickettsiosis in Atlantic salmon (Salmo salar L.) smolts after intraperitoneal and cohabitant challenge using an EM90‐like isolate: A comparative study

Meza

Inami

Dalum

et al. 2019

“…Fryer (Department of Microbiology, Oregon State University). These cells were cultured at 17°C using Eagle′s minimal essential medium (MEM) supplemented with 10% of foetal calf serum (MEM‐10) as previously described (Smith, Díaz, et al., ).…”

Section: Methodsmentioning

confidence: 99%

Apoptosis inhibition of Atlantic salmon (Salmo salar) peritoneal macrophages by Piscirickettsia salmonis

Díaz

Rojas

Galleguillos

et al. 2017

Self Cite

To improve the understanding of the piscirickettsiosis pathogenesis, the in vivo apoptosis modulation of peritoneal macrophages and lymphocytes was studied in juvenile Salmo salar intraperitoneally injected with Piscirickettsia salmonis. Five fish were sampled at post-exposure days 1, 5, 8 (preclinical), 20 (clinical) and 40 (post-clinical period of the disease), and the leucocytes of their coelomic washings were analysed by flow cytometry (using the JC-1 cationic dye), TUNEL and cytology to detect apoptotic cells. A selective and temporal pattern of apoptosis modulation by P. salmonis infection was observed. Apoptosis in lymphocytes was not affected, whereas it was inhibited in macrophages but only during the preclinical stage of the induced piscirickettsiosis. Hence, it is postulated that P. salmonis inhibits macrophage apoptosis at the beginning of the disease development to survive, multiply and probably be transported inside these phagocytes; once this process is complete, macrophage apoptosis is no longer inhibited, thus facilitating the exit of the bacteria from the infected cells for continuing their life cycle.

“…More recently, studies on P. salmonis have used different fish cell lines such as Atlantic salmon kidney (ASK; Smith et al . ), rainbow trout spleen (RTS‐11) and Atlantic salmon head kidney (SHK‐1; Ramirez et al . ), while alternative cell lines such as Spodoptera frugiperda (SF‐21; Birkbeck et al .…”

Section: Tissue Culturementioning

confidence: 99%

Growth characteristics of the intracellular pathogen, Piscirickettsia salmonis, in tissue culture and cell‐free media

Makrinos

Bowden

2016

Piscirickettsia salmonis is an intracellular bacterium that was first isolated and identified in fish cells. Several types of cell lines have been explored for their ability to provide the bacterium with a host cell to replicate in. Tissue culture has been used for growth and cultivation for nearly two decades, until the facultative nature of P. salmonis was confirmed upon the development of blood- and cysteine-based agar. Since then, research has continued to drive the creation of novel agar and broth formulations in order to improve the efficacy of cultivation of P. salmonis. Until now, the techniques and components used for growth have not been thoroughly discussed. In this review, the methods and formulations for growth of P. salmonis in tissue culture and cell-free media will be examined.