TSO is an abbreviation for Trichuris suis ova; the scientific name for the eggs produced by the pig whipworm. The whipworm is a common intestinal helminth of organic, free-ranging, or wild pigs, and as such, an organism which has always been found in the intermediate environment of many humans.
The concept of using TSO for the treatment of immune diseases is to stimulate the immune system by a substance that is not provoking disease, but brings the defense system of the body back in balance.
The Trichuris suis life cycle: When the helminth deposit eggs in the intestine, these are excreted with the intestinal contents as raw, un-developed (non-embryonated) eggs. In the natural situation, the eggs mature in the soil within 2-4 months, during which process a larva develops inside the egg. Thereafter the eggs are biological active.
In the GMP production, the natural life cycle is mimicked. This is done under high containment level. Thus, the raw material is a natural substance to which humans has been in contact over the course of evolution.
"Helminths and the IBD hygiene hypothesis", Weinstock & Elliott, Inflammatory bowel diseases, 2009