Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: Expression Level of Immunological Factors from Rainbow Trout (Oncorhynchus Mykiss) after Infection with Either Bacterial Or Viral Pathogens.

Authors
item Overturf, Kenneth
item Lapatra, S. - CLEAR SPRINGS BUHL,ID
item Bullock, Daniel

Submitted to: Aquatic Fish Health International Symposium
Publication Type: Proceedings
Publication Acceptance Date: July 24, 2002
Publication Date: October 20, 2002
Citation: Overturf, K.E., Lapatra, S.L., Bullock, D.G. Expression level of immunological factors from rainbow trout (oncorhynchus mykiss) after infection with either bacterial or viral pathogens. Aquatic Fish Health International Symposium. 2002.p. 164

Interpretive Summary: For the assessment of formulated cereal grain diets in fish, the development of innovative molecular techniques is crucial for the identification of relevant factors related to nutrient utilization. For the evaluation of immunological factors relating to fish health, molecular real-time PCR probes and primers were developed and tested on samples isolated from fish exposed to either bacterial or viral pathogens. The fish received three different dosage levels of each pathogen and were harvested at two different time points after exposure. Changes in gene expression were tested in liver, kidney, and spleen and standardized to the expression of a control gene for each sample. Results showed that several of the molecular probes detected expression changes in the level of certain immunological factors that were highly sensitive and correlative with pathogen dose. These probes will now be utilized in testing the effect of certain dietary components on the health of rainbow trout being fed cereal grain diets.

Technical Abstract: For the evaluation of formulated cereal grain diets in fish, the development of innovative molecular techniques is crucial for the identification of relevant factors related to nutrient utilization. For the evaluation of immunological factors relating to fish health, molecular real-time PCR probes and primers were developed and tested on samples isolated from fish exposed to either bacterial or viral pathogens. Individual groups of fish were infected with either of three different pathogenic microorganisms, Flavobacterium psychrofilum, Aeromonas salmonicida, or infectious haematopoetic necrosis virus (IHNV). The pathogenic agents were dosed at three different levels and samples from infected and mock infected fish were taken at two different time points after infection. Sample points were 1 day and 5 days post infection. Ten fish were harvested for each experimental point and the liver, spleen and head kidney were isolated for study. The organs from 5 of these animals were plated in tissue culture and examined for presence and level of pathogenic agent. These same organs were isolated from the remaining five animals and total RNA was extracted. The RNA from these organs was then examined for the level of expression of the following immunological related factors, interferon (MX-1), interleukin 8 (IL-8), CD-8, complement factor 3 (C-3), lysozyme, and tumor necrosis factor and they were also examined for the level of B-actin which was used as a standardization control for cellular RNA expression. Using real-time PCR with fluorescent labeled probes it was found that infection with A. salmonis and IHNV showed significant increases in response levels, some of which correlated highly with pathogen dose.

Last Modified: 10/25/2014
Footer Content Back to Top of Page