A story in the online publication National Observer last year highlighted what appeared to be a significant rise in the use of laboratory animals in Canada, as indicated by a report from the Canadian Council on Animal Care (CCAC). Although the article did not distinguish among the various types of animals included in the report, the increase was almost entirely due to a rise in the use of fish – to 1.6 million in 2014 (the latest year for which CCAC has statistics), nearly a doubling from two years earlier.
That jump should not come as a surprise to anyone working in the field of genetics, drug discovery, or growth and development, where a great deal of cutting edge research is now conducted with the help of legions of zebrafish. As small and simple as these animals might be in comparison to the iconic lab mouse, they offer some significant advantages. They are much more cost effective to maintain in large numbers and much easier to house in conditions that meet the CCAC’s guidelines for appropriate care. At the same time, many of their biological functions, such as the way the body absorbs cholesterol, are similar to the human equivalent.
Above all, the zebrafish was among the first animals to have its entire genome sequenced – a high-quality reference genome was announced in 2013 – meaning all of its genes can be listed and analyzed. This has led to the ability to produce genetically altered fish for all kinds of research applications. Cardiovascular researchers, for instance, can acquire fish whose hearts have missing chambers, rhythm defects or fewer blood vessels, making it possible to model and explore disease mechanisms when these genes are perturbed.
However, now that zebrafish have emerged as one of the world’s leading models for studying disease processes and potential therapies, Canadian researchers find themselves potentially excluded from participating in much of this work. These humble swimmers have run afoul of a strict set of regulations imposed by the Canada Food Inspection Agency (CFIA), which in 2012 added them to an extensive list of potential carriers of the spring viremia of carp virus, or SVCV, which systemically breaks down the health of fish and could devastate Canada’s freshwater fisheries.
“The only way of bringing zebrafish into the country is if you know they’re SVCV negative,” said Jane Alcorn, who completed her term as the University of Saskatchewan’s veterinarian in 2016 and is now associate dean, research and graduate affairs, in the college of pharmacy and nutrition at U of S. “When it came to researchers wanting zebrafish, for the last couple of years it’s been pretty much impossible to bring these animals into institutions,” she said. “What’s interesting is that this regulation does not apply to the zebrafish imported by the pet fish industry, which enter with no restrictions.”
For University of Toronto neurobiologist Vincent Tropepe, who has relied on zebrafish as part of his work on the nervous system for over 13 years, the sticking point has been with American, European and Japanese commercial fish-breeding facilities similar to ones that provide specific types of fruit flies or mice to laboratories all over the world. CFIA’s demand for virus-free certification means these stock centres must conduct their own analyses of fish being sent to Canada, which represents just a small portion of their overall market.
“They did this for a year,” recalls Dr. Tropepe. “Then they said, ‘We’re not going to do this anymore because no other country imposes these restrictions and we’re not going to spend the money for fish to be certified.’”
He was among 31 Canadian researchers who early in 2016 published a commentary on the problem in the journal Zebrafish. The article outlines how the controlled conditions under which such academics maintain these fish are far less likely to spread SVCV into the environment than the way most aquarium hobbyists handle them. The authors also point to the lack of any evidence-based assessment of this risk that would justify the CFIA’s regulation of these imports.
Dr. Tropepe and others also express their frustration at watching their counterparts abroad make progress that cannot be replicated in their laboratories. By way of example, he cited findings that appeared in Science last November, which identified key agents enabling zebrafish to regrow their spinal cord after injury and could point the way to a similar agent operating in the human body.
That frustration is shared by Sarah Childs, a professor in biochemistry and molecular biology at the University of Calgary, who has thousands of the fish in her lab. The CFIA restriction has left her fish genetically isolated and at risk of problems associated with in-breeding. At the same time, she is also acutely aware of missing out on innovations in her field.
“We haven’t imported in about three years,” she said. “And, ironically, this is at the same time that the zebrafish genome project is making mutations of every single gene in zebrafish. There are stock centres in Europe and the United States that are stockpiling and freezing sperm from all these fish, and if we were allowed to, I would be ordering multiple strains a year. Instead, we are using precious federal funds and valuable research expertise to recreate strains in our own laboratories.”
Over the past few years, Canadian research universities have formally approached the CFIA to attempt to find a practical, cost-effective way of restoring access to the fish without risk of spreading the virus. “So far,” Dr. Childs said, “these deliberations have been fruitless, leaving Canadian zebrafish researchers farther and farther behind their international colleagues.”