Development of an Immunochromatographic Assay Based on Dense Granule Protein 7 for Serological Detection of Toxoplasma gondii Infection

Abstract

Dense granule antigen proteins derived from Toxoplasma gondii (TgGRAs) are potential antigens for the development of diagnostic tools. TgGRA7 and TgGRA14 were detected in the peritoneal fluid of T. gondii-infected mice, suggesting that TgGRAs may be highly antigenic proteins. Here, TgGRA7 and TgGRA14 were evaluated as candidates for the development of a marker for a rapid diagnostic test. The specificity and sensitivity of purified recombinant proteins of TgGRA7 and TgGRA14 were compared in an indirect enzyme-linked immunosorbent assay (iELISA) using a series of serum samples from T. gondii-experimentally infected mice and using recombinant T. gondii major surface antigen 2 (TgSAG2) as a reference control. The iELISA with TgGRA7 showed the greatest diagnostic accuracy and could detect anti-TgGRA7 antibody in acute and chronic infections. A total of 59 field samples from pigs were also examined by the iELISAs, and the results compared with those of the latex agglutination test (LAT). Among the three recombinant antigens, TgGRA7 had the highest rates of positivity, with significant concordance (88.14) and kappa value (0.76) in comparison with the results using LAT. Furthermore, an immunochromatographic test (ICT) based on recombinant TgGRA7 was developed for rapid detection of antibodies to the infection. The ICT differentiated clearly between sera from T. gondii-infected mice and uninfected or Neospora caninum-infected mice. Pig sera were examined with the ICT, and the results compared favorably with those of LAT and iELISA for TgGRA7, with kappa values of 0.66 and 0.70 to 0.79, respectively. These data suggest that the ICT based on TgGRA7 is a promising diagnostic tool for routine testing in the clinic and mass screening of samples in the field.

A novel dynamic flow immunochromatographic test (DFICT) using gold nanoparticles for the serological detection of Toxoplasma gondii infection in dogs and cats

“…Furthermore, to reduce or counteract matrix interference throughout the reaction system, the sample pad needs to be pretreated or the serum sample is mixed with a serum dilution buffer before being added to the sample hole (Pengsuk et al, 2013;Terkawi et al, 2013). In our new method, only a 5 mL serum sample is needed, and the sample can be applied directly onto the membrane without serum dilution buffer, making the sample pad unnecessary.…”

“…Many studies have reported the successful detection of pathogens using this assay (Pengsuk et al, 2013;Sun et al, 2013). Some studies also have focused on detection of antibodies against T. gondii using this assay (Terkawi et al, 2013). Compared with other serologic tests, ICT is an economical, simple, and rapid approach, which makes it suitable for clinical and field applications (Peng et al, 2007).…”

Sero-prevalence and risk factors associated with toxoplasma gondii infection among pregnant women in Alexandria, Egypt

“…20 Terkawi et al, developed ICT based on recombinant dense granules antigen protein derived from T.gondii (TgGRA7) for rapid detection of antibodies to the infection. 21 A total 59 serum sample from pigs were examined with ICT and compared with those with ELISA. The sensitivity and specificity of ICT was 72.7% and 100 % respectively with a Kappa value of 0.70 (substantial agreement).…”

Toxoplasma gondii Infection in Mice Impairs Long-Term Fear Memory Consolidation through Dysfunction of the Cortex and Amygdala

“…Moreover, mice were sacrificed at 45 and 54 dpi for histopathological analysis and for quantitation of the parasite load using quantitative PCR, respectively. Successful establishment of latent infection was confirmed using an enzyme-linked immunosorbent assay for detecting antibodies to the T. gondii dense granule protein 7 (TgGRA7) (39). Mice with no anti-TgGRA7 antibodies were excluded from the experiments.…”