Screening for active toxoplasmosis in patients by DNA hybridization with the ABGTg7 probe in blood samples

Abstract

We report the potential use of a specific Toxoplasma gondii DNA probe (ABGTg7). We applied a dot blot hybridization assay to blood samples for the diagnosis of cerebral toxoplasmosis (CT), acute toxoplasmic lymphadenopathy (ATL), and disseminated toxoplasmosis in transplant recipients (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 with ATL, resulting in T. gondii DNA detection for 10 patients (58.8%). A comparative study between dot blot and PCR assays performed with the blood of mice that had been experimentally infected with tachyzoites gave similar results: 60 and 70% positive results, respectively. Finally, the sum of positive values obtained by both DNA tests (dot blot assay plus PCR) increased the rate of positivity for ATL patients to 76.4%. These results demonstrate that the T. gondii ABGTg7 repetitive DNA element is an additional useful resource for diagnosing Toxoplasma parasitemia in patients with CT and ATL and in TRs. Thus, our ABGTg7-based dot blot test may lead to an improvement in T. gondii detection methods in patients with acute toxoplasmosis.

Detection of HumanToxoplasma-Specific Immunoglobulins A, M, and G with a RecombinantToxoplasma gondiiRop2 Protein

“…In recent years, molecular biology techniques, such as PCR or dot blot analysis, have been applied for the detection of T. gondii DNA in clinical samples (3,22). However, serological tests are the basic approach for screening purposes or to determine the infection phase.…”

Characterisation of a novel interspersedToxoplasma gondiiDNA repeat with potential uses for PCR diagnosis and PCR-RFLP analysis

“…Genomic DNA and chromosomal DNA agarose blocks were prepared as described previously [3,4]. Following electrophoresis, gels were blotted onto nylon membranes (Hybond, Amersham) by vacuum (Pharmacia LKB, VacuGene XL).…”

“…Repeated DNA elements could be useful as tools for diagnosis as well as for restriction fragment length polymorphism (RFLP) analysis. Regarding diagnosis, active T. gondii infection could be detected from clinical samples using ABGTg7 as a probe [4]. Thus, primers designed from the TGR1E sequence are commonly used for polymerase chain reaction (PCR) for the diagnosis of toxoplasmosis [5,6].…”

Characterisation of a novel interspersed Toxoplasma gondii DNA repeat with potential uses for PCR diagnosis and PCR-RFLP analysis

“…Genomic DNA and chromosomal DNA agarose blocks were prepared as described previously [3,4]. Following electrophoresis, gels were blotted onto nylon membranes (Hybond, Amersham) by vacuum (Pharmacia LKB, Vacu-Gene XL).…”

“…Repeated DNA elements could be useful as tools for diagnosis as well as for restriction fragment length polymorphism (RFLP) analysis. Regarding diagnosis, active T. gondii infection could be detected from clinical samples using ABGTg7 as a probe [4]. Thus, primers designed from the TGR1E sequence are commonly used for polymerase chain reaction (PCR) for the diagnosis of toxoplasmosis [5,6].…”