Abstract: AIM: To detect the presence of Toxoplasma gondii in lymph node tissue in patients
with Toxoplasma infection. METHODS: T.gondii ( RH strain ) specific DNA fragment clones were
obtained by using PCR and gene recombination technique. The DNA fragments used as hybridization
probes were labelled with digoxigenin by random primer method. The technique of in situ
hybridization (ISH) was used to detect T.g DNA in the lymph node sections. RESULTS: Four out of 120 samples T. g DNA were found positive, one with Hodgkins disease (HD ) (1/32) , one with non-Hodgkin’s lymphoma (NHL ) (1/41) and 2 with chronic lymphadenitis (CL ) (2/47). The total positive rate was 3.3%. It was demonstrated that this highly specific probe could detect 10 pg of the total RH strain T. g DNA. CONCLUSION: ISH was applicable in detecting pathogens in the lymphnode tissues of individuals with Toxoplasma infection.

Key words: Toxoplasma gondii, lymph node tissue, DNA hybridization in situ