Comparison of the RE-529 sequence and B1 gene for Toxoplasma gondii detection in blood samples of the at-risk seropositive cases using uracil DNA glycosylase supplemented loop-mediated isothermal amplification (UDG- LAMP) assay

Diagnosis of toxoplasmosis is an important issue, especially in at-risk patients. The molecular methods showed a
promising future for such diagnosis; however, the method itself and the target sequence to be detected is an
important part of accurate detection of the infection. The aim of the present study was to evaluate the RE-529
sequence and B1 gene for Toxoplasma gondii detection in blood samples of the at-risk seropositive cases using
uracil DNA glycosylase supplemented loop-mediated isothermal amplification (UDG-LAMP) assay. In this study,
110 T. gondii seropositive at-risk individuals (pregnant women and immunocompromised patients) and 110
seronegative controls were enrolled. The two most studied sequences (RE-529 and B1) were used and compared
for accurate and reliable detection of T. gondii in blood samples using UDG-LAMP assay and compared with real-
time PCR method. The detection limit, accuracy, and reliability of UDG-LAMP for the parasite's DNA were also
studied. Among 110 studied cases, 39 (35.45%) and 36 (32.7%) were positive for T. gondii DNA with the RE-
LAMP and B1-LAMP, respectively. The seronegative cases remained negative for T. gondii DNA with the studied
genes, however, there were few false negatives compared with real-time PCR method. The detection limit of the
UDG-LAMP for both DNA targets was 0.16 tachyzoite's DNA per reaction tube. Based on the results of this study,
the RE-529 sequence has a better detection rate compared to the B1 gene for toxoplasmosis among at-risk
people. UDG-LAMP is a highly sensitive, accurate, and reliable method with no false-positive results for the
diagnosis of T. gondii infection in blood specimens, however few cases may be misse