Identification of Toxoplasma gondii and Encephalitozoon cuniculi by immunoperoxidase techniques and electron microscopy, in stored, formalin-fixed, paraffin-embedded tissue
Bjerkås, I.; Landsverk, T.
Acta Veterinaria Scandinavica 27(1): 11-22
1986
ISSN/ISBN: 0044-605X PMID: 3092604 Document Number: 281503
The peroxidase-antiperoxidase (PAP) avidin-biotin-complex (ABC) techniques and electron microscopy were used to identify protozoan parasites in formalin-fixed tissue in paraffin blocks, which had been stored for up to 18 years, from 18 cases of suspected toxoplasmosis and encephalitozoonosis. With the ABC method a higher dilution of primary antibody could be used than with the PAP method. With both methods a distinct reaction occurred with appropriate dilutions. The age of the material did not affect the result. Frequently, phagocytized and necrotic parasites were also stained. Cystozoites (bradyzoites) of T. gondii were stained faintly compared to the endozoites (tachyzoites). A Toxoplasma-like parasite from a dog did not react with anti-Toxoplasma serum, and ultrastructurally it was consistent with an unidentified cyst-forming sporozoan parasite previously reported in dogs. Electron microscopy, based on paraffin-embedded tissue, seems useful for identification of protozoan parasites and is an alternative to the immunoperoxidase methods.