On the determination of Toxoplasma gondii virulence in mice

Authors: SARAF, POOJA - University Of Tennessee; SHWAB, E - University Of Tennessee; Dubey, Jitender; SU, CHUNLEI - University Of Tennessee

Submitted to: Experimental Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2017
Publication Date: 1/30/2017
Citation: Saraf, P., Shwab, E.K., Dubey, J.P., Su, C. 2017. On the determination of Toxoplasma gondii virulence in mice. Experimental Parasitology. 174:25-30.

Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating under cooked meat from infected animals and food and water contaminated with oocyst. Why some people become ill and even die from toxoplasmosis whereas others remain asymptomatic is largely unknown. The genetic characteristics of T. gondii strains are considered a factor in the pathogenesis on clinical disease. The underlying mechanism for the parasite virulence is also not fully understood. The laboratory mouse is the animal model most often used to assess virulence of T. gondii strains. In the present paper the authors propose a standard method to do this. These results will be useful for parasitologists and biologists.

Technical Abstract: Toxoplasma gondii is one of the most successful pathogens on earth, capable of infecting mammals and birds. Numerous papers and reports are published on isolation of T .gondii from various natural sources worldwide. The house mouse (Mus musculus) has been used as the laboratory animal model to determine the virulence of T. gondii, which may provide information to study potential association of virulence in mice with severity of human toxoplasmosis. However, many factors, including routes of infection, life stage of T. gondii, number of passages in mice or cell culture, and strains of the mice may have different impact on virulence measurements, making it difficult to compare results among different studies in different laboratories. Here, we discuss factors to be considered when determining T. gondii virulence in mice and propose a simple and effective way of determining and reporting the virulence of T. gondii strains. This approach may facilitate integration of research data in the research community in the future.