Recent trends in molecular diagnostics for Toxoplasma gondii infections

Abstract

Toxoplasmosis is an important parasitic infection of man and animals. It is well-known that the progression and severity of disease depend on the immunological status of the host, but recent studies suggest that the genetics of the parasite can also play a role. Diagnosis based on clinical appearance and serology is not always easy. However, molecular methods do not depend on an immune response, and allow direct detection of the parasite in biological samples. Thus they can be used to establish a diagnosis when serological tests are not definitive. Multicopy sequences specific for Toxoplasma gondii, e.g., the B1 gene or the 529-bp sequence, are especially useful in molecular tests. Real-time PCR is very sensitive and is a promising technique that is capable of providing a quantitative result. Molecular methods are also used for genotypic characterisation of T. gondii isolates. Analysis of polymorphic sequences determines the precise strain. The choice of sequence is critical when undertaking studies on the correlation between clinical signs and symptoms of disease and the T. gondii genotype. Further studies involving direct genotyping of T. gondii from clinical samples are needed.

Adapting a conventional pcr assay forToxoplasma gondiidetection to real-time quantitative pcr including a competitive internal control

“…and the risk of false positive results are decreased. Furthermore, real-time PCR gives quantitative data on the parasitic load (Switaj et al, 2005). A conventional PCR using a pair of primers JW58-JW59 has previously been developed for the detection of the B1 gene of T. gondii (Pelloux et al, 1996).…”

“…This infectious disease can cause congenital toxoplasmosis when maternal infection occurs during pregnancy and severe infections in immunocompromised patients (mainly transplant and AIDS patients). Current diagnosis of toxoplasmosis is based on the results of several techniques: serological detection, cell culture and molecular methods (Switaj et al, 2005). PCR is the major breakthrough for the diagnosis of this infection due to T. gondii.…”

Molecular Detection and Genotyping of Toxoplasma gondii from Clinical Samples

“…No The first protocol for molecular detection of T. gondii, for conventional PCR targeting B1 gene, was developed in 1989 and has since been modified and optimized in many laboratories (Burg et al, 1989;Lopez et al, 1994;Liesenfeld et al, 1994;Reischl et al, 2003;Switaj et al, 2005). The B1 gene, although of unknown function, is widely exploited in a number of diagnostic and epidemiological studies because of its specificity and sensitivity.…”

The Laboratory Diagnosis in Toxoplasma Infection

“…Unfortunately, it is diicult to have a conidentially valor in the PCR assays. For a pre-natal diagnosis, the reported sensibility goes from 64 to 97.4% with a predictive negative value of 87.7-99.7%, respectively; in case of patients with AIDS and toxoplasmosis, the reported sensibility goes from 13 to 87.5% [49]. With the detection of the sequence REP 529-bp, a sensibility of 100% has been reported in amniotic luids [48].…”