Pigs offer insights into human parasite infection

Pigs and humans show similar immune responses to Toxoplasma, a parasite carried by many people and animals worldwide.

The findings strengthen the case for studying the resulting disease in pigs.

They offer a potential route to studying toxoplasma infection, which is usually mild, but can lead to life-threatening complications in people with weakened immune systems and during pregnancy. The parasite can also affect livestock, including pigs, with impacts on animal health and productivity.

This work by Roslin scientists builds on previous evidence that toxoplasmosis in pigs mimics key aspects of human infection, and adds insight by directly comparing gene activity across species.

Immune mechanisms

Pigs are considered reliable models for studying toxoplasmosis because they develop disease in ways that resemble human infection, unlike traditional mouse models, researchers explain.

The team tested human and pig versions of two genes that control immunity, IRF1 and IDO1, in lab-grown cells and found that, when the cells were exposed to the parasite, growth was limited in both species.

The IDO1 gene helps starve the parasite of nutrients it needs to survive, while IRF1 switches on additional genes involved in fighting infection.

Results also show that in pig cells that lacked the immune-signalling genes, introducing human versions of these genes could restore immune activity, showing how similarly the immune mechanisms work in both species.

Blocking either pig or human genes in pig cells also restored the parasite’s ability to grow, confirming the role of both genes in controlling infection.

The work could contribute to a One Health approach to tackling the parasite, developing strategies that benefit both human and animal health. In the longer term, this could include new ways to reduce infection in livestock or improve resistance to disease in vulnerable people.

This research was published in Frontiers in Immunology.

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