Evaluation of Serological and Molecular Tests Used for the Identification of Toxoplasma gondii Infection in Patients Treated in an Ophthalmology Clinic of a Public Health Service in São Paulo State, Brazil

Abstract

Ocular toxoplasmosis is one of the most common complications caused by the infection with the parasite Toxoplasma gondii. The risk of developing eye lesions and impaired vision is considered higher in Brazil than other countries. The clinical diagnosis is difficult and the use of sensitive and specific laboratorial methods can aid to the correct diagnosis of this infection. We compared serological methods ELISA and ELFA, and molecular cPCR, Nested PCR and qPCR for the diagnosis of T. gondii infection in groups of patients clinically evaluated with ocular diseases non-toxoplasma related (G1 = 185) and with lesions caused by toxoplasmosis (G2 = 164) in an Ophthalmology clinic in Brazil. Results were compared by the Kappa index, and sensitivity (S), specificity (E), positive predictive value (PPV), and negative (NPV) were calculated. Serologic methods were in agreement with ELISA more sensitive and ELFA more specific to characterize the acute and chronic infections while molecular methods were discrepant where qPCR presented higher sensitivity, however, lower specificity when compared to cPCR and Nested PCR.

The Role of microRNAs in the Infection by T. gondii in Humans

“…The presence of these antibodies with the avidity of IgG can be an essential tool to determine the timing of infection (Montoya, 2002;Murata et al, 2016;Villard et al, 2016). Molecular approaches can be used as a complement of serological tests when the diagnose is unclear by serology and can be used to detect T. gondii DNA in various samples (Okay et al, 2009;Robert-Gangneux and Darde, 2012;Murata et al, 2017;Murata et al, 2020). The most used targets for T. gondii are the B1 multi-copy gene and the 529 bp repeat element with 35 and 200-300 copies in the T. gondii genome, respectively (Homan et al, 2000;Ivovićet al, 2012;Camilo et al, 2017;Nakashima et al, 2020;Murata et al, 2020).…”

“…Molecular approaches can be used as a complement of serological tests when the diagnose is unclear by serology and can be used to detect T. gondii DNA in various samples (Okay et al, 2009;Robert-Gangneux and Darde, 2012;Murata et al, 2017;Murata et al, 2020). The most used targets for T. gondii are the B1 multi-copy gene and the 529 bp repeat element with 35 and 200-300 copies in the T. gondii genome, respectively (Homan et al, 2000;Ivovićet al, 2012;Camilo et al, 2017;Nakashima et al, 2020;Murata et al, 2020). Although molecular tests for the diagnosis of toxoplasmosis are becoming more frequent, they are still controversial, and there is no agreement about the best method or target to be used (Garweg et al, 2011;Maenz et al, 2014;Greigert et al, 2019;Murata et al, 2020).…”

“…The most used targets for T. gondii are the B1 multi-copy gene and the 529 bp repeat element with 35 and 200-300 copies in the T. gondii genome, respectively (Homan et al, 2000;Ivovićet al, 2012;Camilo et al, 2017;Nakashima et al, 2020;Murata et al, 2020). Although molecular tests for the diagnosis of toxoplasmosis are becoming more frequent, they are still controversial, and there is no agreement about the best method or target to be used (Garweg et al, 2011;Maenz et al, 2014;Greigert et al, 2019;Murata et al, 2020). Also, the concentration of T. gondii DNA during chronic infection is usually undetectable even when molecular sensitivity tests are performed (Ivovićet al, 2012).…”

“…The use of a test that could detect T. gondii infection in earlier stages would be ideal, mainly during pregnancy, as early treatment of infected mothers seems to decrease the risk of transmission and severity to the foetus improving clinical outcomes (Wallon et al, 2013;Begeman et al, 2017). Expression of microRNAs may precede IgM class antibodies in parasitic diseases since that IgM antibodies may eventually be undetected within the first weeks following infection (Murata et al, 2020). Furthermore, the microRNAs may be biomarkers of high sensitivity and specificity for diagnosis at different stages of infection.…”

The Potential Contribution of ABO, Lewis and Secretor Histo-Blood Group Carbohydrates in Infection by Toxoplasma gondii

“…Laboratory diagnosis of toxoplasmosis is essentially serological, but a set of molecular methods detect T. gondii genomic DNA in different biological samples (Liu et al, 2015;Dard et al, 2016). Serology detecting IgM and IgG anti-T. gondii antibodies and PCR (conventional PCR, Nested PCR, Real-Time PCR) are standard methods in determining acute and chronic infection (Okay et al, 2009;Saki et al, 2019;Murata et al, 2020).…”