Toxoplasma gondii

Toxoplasma gondii is a genus of parasitic protozoa (cats being the dfinitive host). It can also be carried by the vast majority of warm-blooded animals, including humans. Toxoplasma gondii belongs to the phylum Apicomplexa and is the only known member species of the genus Toxoplasma. The life cycle of T. gondii has two phases. The sexual part of the life cycle (coccidia-like) occurs only in members of the Felidae family (domestic and wild cats), which makes these animals the parasite’s primary host. The asexual part of the life cycle can occur in any warm-blooded animal, such as other mammals (including felines) and birds.

Toxoplasmosis, the disease it causes, is usually minor and self-limiting but can have serious or even fatal e ects on an immunocompromised human or cat, or on a fetus whose mother first contracts the disease during pregnancy. The most notable manifestation of Toxoplasmosis in immunocompromised patients is Toxoplasmic Encephalitis, which can be deadly. If infection with T. gondii occurs for the first time during pregnancy, the parasite can cross the placenta, possibly leading to Hydrocephalus or Microcephaly, Intracranial Calcification, and Chorioretinitis, with the possibility of spontaneous abortion (miscarriage) or intrauterine death.

Anti-Toxoplasma is a purified immunoglobulin fraction of rabbit antiserum that is filter sterilized and diluted in buffer pH 7.5, containing BSA and sodium azide as a preservative.

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   2003;November

1. Cut and mount 3-4 micron formalin-fixed paraffin-embedded tissues on positive charged slides.
2. Air dry for 2 hours at 58° C.
3. Deparaffinize, dehydrate and rehydrate tissues.
4. Subject tissues to heat epitope retrieval using a suitable retrieval solution such as ImmunoDNA Retriever with Citrate (BSB 0020-BSB 0023) or EDTA (BSB 0030-BSB 0033).
5. Any of three heating methods may be used:
   • Electric Pressure Cooker
     Place standoff rack at base of pressure cooker. Add 1-2 inches of distilled water to the pressure cooker and turn heat to high, and incubate for 15 minutes. Open and immediately transfer slides to room temperature.
   • Water Bath Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a water bath set at 95°-99° C. Incubate for 30-60 minutes.
   • Conventional Steamer Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a Steamer, cover and steam for 30-60 minutes.
6. After heat treatment, transfer slides in ImmunoDNA Retriever with Citrate or EDTA to room temperature and let stand for 15-20 minutes.
7. Wash slides with IHC wash buffer or DI water.
8. Continue IHC staining protocol.