Biomarkers seen as good way forward in improving diagnosis of pythiosis in horses

Pythium hyphae. Image: Public domain, via Wikimedia Commons

Biomarkers present a good option to improve the diagnosis of pythiosis in horses and humans, according to researchers.

Pythiosis is caused by Pythium insidiosum — a fungus-like microorganism known as an oomycete. Oomycetes, often referred to as water molds, were once classified as fungi because of similarities in their appearance and lifestyle. However, molecular and phylogenetic studies have revealed significant differences.

Pythiosis is an emerging and life-threatening disease that occurs most frequently in tropical and subtropical countries, affecting several animal species, especially horses, dogs, and humans.

P. insidiosum colonizes aquatic plants in which asexual reproduction occurs via the production of sporangia. When mature, these rupture and release zoospores, the infective form of the microorganism. These zoospores move in the water until they find another plant, or an animal with injured tissue in which they encyst.

The resulting infection, known as pythiosis, is frequently found in horses in Brazil and humans in Thailand. It is difficult to diagnose because it is often misdiagnosed under the microscope as a fungal infection.

In horses, skin lesions form in which branch-like hyphae can be observed, often covered by necrotic cells that form white-yellowish masses called “kunkers”. There is also an intestinal form of the disease, which can trigger colic.

There is no specific antigen to use for rapid diagnosis, the availability of which could improve the prognosis in different animal species.

Jéssica Luana Chechi and her fellow researchers, in a study published in the Journal of Fungi, set out to determine which P. insidiosum antigens are recognized by circulating antibodies in infected horses in Brazil and infected humans in Thailand.

They identified 23 protein spots, 14 of which were recognized by pooled serum from horses and humans. Seven antigens were commonly recognized by both species.

“These results demonstrate that there are common antigens recognized by the immune responses of horses and humans, and these antigens may be studied as biomarkers for improving diagnosis and treatment,” they said.

The matching antigens identified in the study may be promising for studying new methods for diagnosing and treating pythiosis, they said.

The study team comprised Chechi, Tiwa Rotchanapreeda, Giselle Souza da Paz, Ana Carolina Prado, Alana Lucena Oliveira, José Cavalcante Souza Vieira, Marília Afonso Rabelo Buzalaf, Anderson Messias Rodrigues, Lucilene Delazari dos Santos, Theerapong Krajaejun and Sandra de Moraes Gimenes Bosco, affiliated with a range of institutions in Brazil and Thailand.

Chechi, J.L.; Rotchanapreeda, T.; da Paz, G.S.; Prado, A.C.; Oliveira, A.L.; Vieira, J.C.S.; Buzalaf, M.A.R.; Rodrigues, A.M.; Santos, L.D.d.; Krajaejun, T.; Bosco, S.d.M.G. Prospecting Biomarkers for Diagnostic and Therapeutic Approaches in Pythiosis. J. Fungi 2021, 7, 423.

The study, published under a Creative Commons License, can be read here

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