Identification of Potential Serodiagnostic and Subunit Vaccine Antigens by Antibody Profiling of Toxoplasmosis Cases in Turkey

Abstract

Toxoplasmosis, caused by infection of the protozoan parasite Toxoplasma gondii, is associated with mild disease in healthy individuals, whereas individuals with depressed immunity may develop encephalitis, neurologic disorders, and other organ diseases. Women who develop acute toxoplasmosis during pregnancy are at risk of transmitting the infection to the fetus, which may lead to fetal damage. A diagnosis is usually confirmed by measuring IgG, or IgM where it is important to determine the onset of infection. A negative IgM result essentially excludes acute infection, whereas a positive IgM test is largely uninterpretable because IgM can persist for up to 18 months after infection. To identify antigens for improved diagnosis of acute infection, we probed protein microarrays displaying the polypeptide products of 1357 Toxoplasma exons with well-characterized sera from Turkey. The sera were classified according to conventional assays into (1) seronegative individuals with no history of T. gondii infection; (2) acute infections defined by clinical symptoms, high IgM titers, and low avidity IgG; (3) chronic/convalescent cases with high avidity IgG but persisting IgM; (iv) true chronic infections, defined by high avidity IgG and no IgM. We have identified 38 IgG target antigens and 108 IgM target antigens that can discriminate infected patients from healthy controls, one or more of which could form the basis of a 'tier-1 test to determine current or previous exposure. Of these, three IgG antigens and five IgM antigens have the potential to discriminate chronic/ IgM persisting or true chronics from recent acutely infected patients (a 'tier-2 test). Our analysis of the antigens revealed several enriched features relative to the whole proteome, which include transmembrane domains, signal peptides, or predicted localization at the outer membrane. This is the first protein microarray survey of the antibody response to T. gondii, and will

Discovery of Potential Diagnostic and Vaccine Antigens in Herpes Simplex Virus 1 and 2 by Proteome-Wide Antibody Profiling

“…Owing to the small volumes of sera required to probe arrays and the ease with which they can be screened in a high-throughput fashion, the array platform is ideal for seroepidemiological studies against hundreds of pathogen antigens simultaneously (20,31,49,52). Seroprevalence of HSV is influenced by age, sexual activity, and ethnicity, and a much larger study would be required to estimate seroprevalence in the United States properly using the array platform.…”

rROP2186–533: A Novel Peptide Antigen for Detection of IgM Antibodies AgainstToxoplasma gondii

“…Recently, Liang et al (2011) identified several antigens for detection of IgM antibodies using protein microarray displaying the polypeptides products of Toxoplasmic exons with well-characterized sera. Usually, IgM antibodies are generated within a week after infection, reaching a peak, and then rapidly decrease.…”

Peptide Microarray Analysis ofIn Silico-Predicted Epitopes for Serological Diagnosis of Toxoplasma gondii Infection in Humans

“…Peptides can be arranged in microarrays, thus allowing simultaneous analysis of up to several thousands of peptides with a single serum sample. With this technique, global patterns of antibody responses to various infectious agents were studied (3,35,36,42,44).…”