Location: Animal Parasitic Diseases LaboratoryTitle: Acid-fast lipids are important structural components of oocyst walls of Cryptosporidium, Toxoplasma, and Eimeria Author
Submitted to: mBio
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2013
Publication Date: 10/1/2013
Citation: Bushkin, G., Motari, E., Carpienteri, A., Dubey, J.P., Costello, C., Robbins, P., Samuelson, J. 2013. Acid-fast lipids are important structural components of oocyst walls of Cryptosporidium, Toxoplasma, and Eimeria. mBio. DOI: 10.1128/mBio.003787. 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 oocysts. The oocyst is the key for successful transmission of the parasite. The chemical and physical basis of the resistance of the oocyst are largely unknown. In the present study, authors explain the chemical nature of the walls of the oocysts. The results will be useful in discovering disinfectants that will dissolve both walls of the oocyst. The results should be of interest to biologists and parasitologists.
Technical Abstract: Coccidia are protozoan parasites that cause significant human disease and are of major agricultural importance. Cryptosporidium spp.cause diarrhea in humans and animals, while congenital Toxoplasma infections causes blindness and death. Eimeria kills chickens, so all poultry feed contain antibiotics against this parasite. Oocysts, which are the diagnostic and infectious stage of coccidia, have a multilayered wall that is not well understood. Recently we showed that the inner layer of the oocyst walls of Toxoplasma and Eimeria is a porous scaffold of fibers of ß-1,3-glucan, which are also present in fungal walls but are absent from Cryptosporidium oocyst walls. Here we demonstrate astructural role for lipids in the oocyst walls of Cryptosporidium, Toxoplasma, and Eimeria. Briefly, oocyst walls of each organism label with acid-fast stains that bind to lipids in the walls of mycobacteria. Polyketide synthases similar to those that make mycobacterial wall lipids are extraordinarily abundant in oocysts of Toxoplasma and Eimeria and are predicted in Cryptosporidium. The outer layer of oocyst walls of Toxoplasma and Eimeria and the entire oocyst wall of Cryptosporidium are dissolved by organic solvents. Oocyst wall lipids (similar for all three coccidia) are complex mixtures of triglycerides that contain polyhydroxy fatty acyl chains like those present in cutin (part of the waxy coat on the surface of plant leaves). We propose a two-layered model of the oocyst wall (glucan and acid-fast lipids) that resembles two-layered walls of mycobacteria (peptidoglycan and acid-fast lipids) and plants (cellulose and cutin).