[Biological properties of Toxoplasma gondii (Coccididia) that produce oocysts].

Invasional, pathogenic and immunoserological properties of endogenic and exogenic stages of development of two strains of T. gondii were studied on mice, rabbits and chicks. After the parenteral infection cysts and oocysts represented more pathogenic stages. At the peroral infection of animals oocysts were found to be more pathogenic as compared to cysts. The earliest immunological response and the highest titres of antibodies were obtained from animals subjected to peroral administration of oocysts. Trophozoites had weak antigene properties especially after the peroral injection.