Discovery of new Toxoplasma gondii antigenic proteins using a high throughput protein microarray approach screening sera of murine model infected orally with oocysts and tissue cysts.

BACKGROUND

Toxoplasma gondii is an obligate intracellular protozoan parasite that causes congenital toxoplasmosis, as well as other serious clinical presentations in immune compromised humans. The parasite has also been recently linked to behavioral diseases in humans and other mammalian hosts. New antigens are being evaluated to develop a diagnostic kit for the diagnosis of acute infection or a protective vaccine.

METHODS

In this study, we have focused on the discovery of new antigenic proteins from T. gondii genomic data using a high throughput protein microarray screening. To date, microarrays containing > 2870 candidate exon products of T. gondii have been probed with sera collected from patients with toxoplasmosis. Here, the protein microarrays are probed with well-characterized serum samples from animal models administered orally with oocysts or tissue cysts. The aim was to discover the antigens that overlap in the mouse profile with human antibody profiles published previously. For this, a reactive antigen list of 240 antigens recognized by murine IgG and IgM was identified using pooled sera from orally infected mice.

RESULTS

Analyses of screening data have identified plenty of antigens and showed strong immunogenicity in both mouse and human antibody profiles. Among them, ROP1, GRA2, GRA3, GRA4, GRA5, GRA6, GRA7, GRA8, GRA14, MIC1, MIC2 and MAG1 have shown strong immunogenicity and used as antigen in development of vaccines or serological diagnostic assays in previous studies.

CONCLUSION

In addition to the above findings, ROP6, MIC12, SRS29A and SRS13 have shown strong immunogenicity but have not been tested in development of a diagnostic assay or a vaccine model yet.