SCREENING FOR ACTIVE TOXOPLASMOSIS IN PATIENTS BY DNA HYBRIDIZATION WITH THE ABGTG7 PROBE IN BLOOD-SAMPLES

We report the potential use of a specific Toxoplasma gondii DNA probe (ABGTg7). We applied a dot blot hybridization assay to blood samples f or the diagnosis of cerebral toxoplasmosis (CT), acute toxoplasmic lym phadenopathy (ATL), and disseminated toxoplasmosis in transplant recip ients (TRs). We studied a total of 84 individuals: 38 patients and 46 controls, We found positive hybridization signals for 12 (66.7%) of 18 patients with confirmed CT, 9 (52.9%) of 17 patients with ATL, and 2 (66.7%) of 3 TRs. PCR assays were performed in parallel for patients w ith ATL, resulting in T. gondii DNA detection for 10 patients (58.8%). A comparative study between dot blot and PCR assays performed with th e blood of mice that had been experimentally infected with tachyzoites gave similar results: 60 and 70% positive results, respectively. Fina lly, the sum of positive values obtained by both DNA tests (dot blot a ssay plus PCR) increased the rate of positivity for ATL patients to 76 .4%. These results demonstrate that the T. gondii ABGTg7 repetitive DN A element is an additional useful resource for diagnosing Toxoplasma p arasitemia in patients with CT and ATL and in TRs. Thus, our ABGTg7-ba sed dot blot test may lead to an improvement in T. gondii detection me thods in patients with acute toxoplasmosis.