Immune Challenger Assay


The fish intestine comprises an important environment-organism interface that is vital to fish growth, health and pathogen defence. We offer in vitro tests to analyze the toxicity of chemicals and/or the response of fish intestinal cells to viral and bacterial stimuli by means of the rainbow trout (Oncorhynchus mykiss), epithelial cell line. This cell line can be employed 2D as adherent monolayer or 3D in a two-compartment system, both in static as well as flow-through exposures.


The Immune Challenger Assay focuses on the immune response of the intestinal epithelial cells on the gene expression level. Two options are available: option 1 mimics a prior immune challenge while option 2 implies a simultaneous immune and chemical challenge.

Option 1

RTgutGC cells are first exposed to bacterial lipopolysaccharide (LPS) (mimics bacterial infection) or Poly(I:C) (structurally similar to double-stranded RNA, mimics viral infection) for 5 h to activate the cellular immune system prior to application of the test item.

Option 2

RTgutGC cells are exposed to LPS or Poly(I:C) and the test item at the same time for 10 h before analysis of gene expression.

The set of marker genes can be adopted to customer needs. Examples of standard immune markers are Interleukin-1b (mediator of inflammatory response), TNFalpha (regulator of immune cells), NF-kB (regulator of immune response to infection) or IL-1b.

Relevant publications:

  • Schug H, Yue Y, Krese R, Fischer S, Kortner TM, Schirmer K. (2019). Time- and concentration-dependent expression of immune and barrier genes in the RTgutGC fish intestinal model following immune stimulation. Fish and Shellfish Immunology 88, 308-317.