A chilling immune system: Low temperatures slow down fish immune response to infection

Wednesday, January 11, 2017

Fumehood with glassware and samples

Byline: Éric Le Dreff-Kerwin, Bioloyg MSc. student

The sudden decrease in sporting fish is leading to a potential ecological disruption, if not an economical loss. Due to a lowering in water temperatures, walleye are doing more than wish they could wrap themselves up in a warm blanket.

When infected by a virus in the summer, walleye are able to fend off the attack. But in the fall when the temperature cools, symptoms of skin tumours appear. It’s this reappearance of the virus when temperatures are low that ultimately kills the fish.

Quinn Abrams, a new Biology Master’s student in Prof. Brian Dixon’s research lab at the University of Waterloo, is trying to discover how low temperatures change the fish’s immune response to infection.

It would give us an opportunity to develop conservation strategies to potentially conserve the fish species where they are currently found.

Typically, infected cells break up the virus and present at the cell’s surface. The virus fragments are held in place until an immune cell recognizes it and initiates the immune response. This fast-acting process, known as the endogenous antigen presenting pathway, inactivates the virus, minimizing the spread of disease.

One virus, the walleye dermal sarcoma virus, has found a way to beat this pathway and infect the fish when the water temperature gets cold in the fall.

We see the impact of global warming, specifically in areas where you see colder temperatures.

Abrams is using walleye skin cell cultures, that is cells growing in an artificial environment separate from the organism, and observing the change in infection rate and immune response when exposed to the virus at varying temperatures.

Abrams hypothesizes that the speed of the protein involved in the immune response have decreased and the virus is capable of spreading its infection. Understanding how this virus is capable of surviving and killing fish after living inside of them for months is of great interest to many biologists.

Prof. Brian Dixon holds a Canada Research Chair in Fish and Environmental Immunology.

NOTE: BIOL 690 Scientific Communication is a graduate course that helps students enhance their skills in the acquisition, organization and presentation of scientific information. Students in the course interviewed and wrote a news story about one of their classmates' research.