Zebrafish Eyed as Ideal Toxoplasmosis Research Model

Researchers at Oregon State University (OSU) have identified zebrafish as an optimal testing model for toxoplasmosis, as they believe the fish could provide insight into breakthrough treatments.

One of the most prevalent parasites, Toxoplasma (T.) gondii infects nearly 1 in 3 humans and a myriad of other species. Since parasites frequently have similar biologies as their host, treating patients with toxoplasmosis poses a challenge for many doctors, according to an OSU news release.

In study results published online in the Journal of Fish Diseases, investigators infected 22 zebrafish with T. gondii, the parasite responsible for transmitting toxoplasmosis. The fish were originally kept in 82.4 degree water and researchers raised the temperature 1 degree until reaching 98.6 degrees, where they were left for 3 weeks.

In doing so, the authors reported that temperature was very influential in how zebrafish interacted with the parasite. By raising the temperature of the zebrafish habitat to 98.6 degrees—the same as the human body—the team found while T. gondii was able to infect the fish, it was unable to kill them.

“There are many elements involved in the restricted host range of intracellular parasites, intrinsic host factors such as specific immunological components, receptors, incompatibility of host cells or parasite-related factors such as permissive environmental conditions, for example temperature,” the investigators wrote. “Our experience with zebrafish suggests that for poikilothermic species, the major limitation to infection is temperature.”

Their study isn’t the first to explore the benefits of using zebrafish as a specimen; recent reports have highlighted their rapid reproduction rates, similar genetics to humans, and biological systems which allows quick compound testing. However, the investigators mentioned their study was the first time T. gondii’s behavior was observed in the fish, the OSU release also pointed out.

“This advance may provide a very efficient tool for the discovery of new therapies for this parasitic infection,” Justin Sanders, an OSU postdoctoral fellow and the study’s lead author commented. “With it we should be able to more easily screen a large library of compounds, at much less expense, and look at things that are unknown or have never been considered as a possible treatment.”