Development of a 3D spheroid cell culture system from fish cell lines for in vitro infection studies: Evaluation with Saprolegnia parasitica

Abstract

Understanding the ways in which pathogens infect host cells is essential to improve and develop new treatment strategies. This study aimed to generate a novel in vitro infection model by establishing a reproducible 3D spheroid cell culture system that may lead to a reduced need for animals in fish disease research. 2D models (commonly cell lines) cannot replicate many key conditions of in vivo infections, but 3D spheroids have the potential to provide bridging technology between in vivo and in vitro systems. 3D spheroids were generated using cells from rainbow trout (Oncorhynchus mykiss) cell lines, RTG‐2 and RTS‐11. The RTG‐2 spheroids were tested for their potential to be infected upon exposure to Saprolegnia parasitica spores. Positive infiltration of mycelia into the spheroids was verified by confocal microscopy. As a closer analogue of in vivo conditions encountered during infection, the straightforward model developed in this study shows promise as an additional tool that can be used to further our understanding of host–pathogen interactions for Saprolegnia and possibly a variety of other fish pathogens.

Advancing animal health and disease research in the lab with three‐dimensional cell culture systems

“…Threedimensional spheroids generated from the rainbow trout fibroblast cell line RTG-2 were shown to be effective for modelling infection by S. parasitica cysts. 41 The cysts successfully germinated and showed targeted growth and penetration into the spheroids throughout the first 24 hours of co-culture. This established a simple platform that negated the use of live fish as experimental models and lays the way as a system to screen anti-pathogen compounds towards the development of future treatments.…”

“…The limited availability of salmon eggs to fully characterise this infection required the development of an in vitro model. Three‐dimensional spheroids generated from the rainbow trout fibroblast cell line RTG‐2 were shown to be effective for modelling infection by S. parasitica cysts 41 . The cysts successfully germinated and showed targeted growth and penetration into the spheroids throughout the first 24 hours of co‐culture.…”

Development and characterization of brain cell line from Trachinotus blochii and its application in virological and gene expression studies

“…To date, 783 cell lines have been developed from marine and fresh water fish species (Thangaraj et al., 2021). Fish cell line is a potential in vitro tool which deals with a variety of applications including screening of viruses followed by viral propagation, vaccine development, (Suryakodi et al., 2021; Zeng et al., 2022), toxicology (Ashafque et al., 2022; Liu et al., 2021), immunological gene expression (Rakus et al., 2019; Ruiz‐Palacios et al., 2020) and host–pathogen interaction (Faber et al., 2021; Wang et al., 2020). The fish cell lines are widely applied in virological and toxicological studies.…”

Derivation and characterization of new cell line from intestine of turbot (Scophthalmus maximus)

“…2022 ), and immunology (Faber et al . 2021 ), and for the isolation and identification of fish viruses (Pham et al . 2020 ; Li et al .…”