Diagnosis of toxoplasmosis and typing of Toxoplasma gondii.

Quan Liu,Si-Yang Huang,Xing-Quan Zhu,Ze-Dong Wang

doi:10.1186/s13071-015-0902-6

Abstract

Toxoplasmosis, caused by the obligate intracellular protozoan Toxoplasma gondii, is an important zoonosis with medical and veterinary importance worldwide. The disease is mainly contracted by ingesting undercooked or raw meat containing viable tissue cysts, or by ingesting food or water contaminated with oocysts. The diagnosis and genetic characterization of T. gondii infection is crucial for the surveillance, prevention and control of toxoplasmosis. Traditional approaches for the diagnosis of toxoplasmosis include etiological, immunological and imaging techniques. Diagnosis of toxoplasmosis has been improved by the emergence of molecular technologies to amplify parasite nucleic acids. Among these, polymerase chain reaction (PCR)-based molecular techniques have been useful for the genetic characterization of T. gondii. Serotyping methods based on polymorphic polypeptides have the potential to become the choice for typing T. gondii in humans and animals. In this review, we summarize conventional non-DNA-based diagnostic methods, and the DNA-based molecular techniques for the diagnosis and genetic characterization of T. gondii. These techniques have provided foundations for further development of more effective and accurate detection of T. gondii infection. These advances will contribute to an improved understanding of the epidemiology, prevention and control of toxoplasmosis.

Highlights

Toxoplasmosis, caused by the obligate intracellular protozoan Toxoplasma gondii, is an important zoonosis with medical and veterinary importance worldwide
Genotyping methods based on molecular technologies For epidemiological studies, it is important to identify genotypes of T. gondii infection, and some molecular technologies, including microsatellite analysis, multilocus sequence typing, polymerase chain reaction (PCR)-RFLP, RAPD-PCR, and highresolution melting (HRM) analysis, have been developed
Serotyping methods based on polymorphic polypeptides T. gondii infection induces a strong and persistent humoral immune response in the hosts

Summary

Serological methods

Antibody/antigen type tested IgG, IgM, IgA IgG IgG, IgM IgG IgG, IgM, IgA, antigens IgM IgG, IgM IgG IgG, IgM IgG, ESA IgG, IgA, IgE. The sandwich ELISA with TLA is more sensitive and more specific to detect human IgM antibodies than IFAT [62], and the sandwich ELISA with recombinant P35 is more specific for the acute infection than IgMELISA using TLA [73, 74] Another sandwich ELISA with anti-MIC10 antibody prepared from two different species can be used to detect circulating antigen MIC10 for early diagnosis of toxoplasmosis [75]. The specific IgM in serum sample will bind to the anti-species IgM and agglutinate fixed parasite antigens, which is observed as that of MAT [79] This test is simpler and easier to perform than the IgM-ELISA, but it requires large numbers of T. gondii tachyzoites. A rapid immunochromatographic strip using colloid gold conjugated antiexcretory/secretory antigens (ESA) IgG antibodies was developed to detect ESA in acute infection of T. gondii as early as 2–4 days post-infection, showing high agreement with ELISA in sensitivity and specificity [83].

Molecular methods

Findings

Conclusion