Design and Optimization of an IgG Avidity ELISA Based on Toxoplasma gondii Lysate Antigen for Differentiating Acute and Chronic Infections in Pregnant Women

Authors

  • Mostafa Tork Toxoplasmosis Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran
  • Shahabeddin Sarvi Toxoplasmosis Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran
  • Hossein Asgarian-Omran Department of Immunology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
  • Mitra Sadeghi Toxoplasmosis Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran
  • Bahare Basirpour Toxoplasmosis Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran
  • Eisa Nazar Orthopedic Research Center, Mazandaran University of Medical Sciences, Sari, Iran
  • Seyed Abdollah Hosseini Toxoplasmosis Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran
  • Ahmad Daryani Toxoplasmosis Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran
  • Sargis A. Aghayan Laboratory of Molecular Parasitology, Scientific Center of Zoology and Hydroecology, NASRA, 7P. Sevak st. Yerevan 0014, Armenia

DOI:

https://doi.org/10.18502/ijpa.v21i3.22589

Keywords:

Toxoplasma gondii; Diagnosis; Antigen; In-house

Abstract

Background: Toxoplasmosis is a significant global health concern. Definitive diagnosis of toxoplasmosis is a serious challenge due to false positive serological results. This study focuses on optimization and standardization of an in-house IgG avidity ELISA for Toxoplasma gondii using freshly prepared Toxoplasma lysate antigen (TLA).

Methods: Samples were collected during routine pregnancy screening. Following tachyzoite purification, TLA concentration was determined by the Bradford assay at 20 μg/mL. The indirect ELISA assay was then performed with a urea treatment step (6 M). Using 75 serum samples classified as acute or chronic toxoplasmosis, the IgG avidity test was performed by ELISA in two rows of microplates with 6 M urea and PBS, and then the avidity index was calculated.

Results: After calculating the cutoff values, the sensitivity and specificity of the in-house Toxoplasma IgG avidity kit were 92% (95% CI: 74–99%) and 100% (95% CI: 86–100%), respectively, with an area under the ROC curve (AUC) of 0.977 (95% CI: 0.951–1.000).

Conclusion: The results of the IgG avidity test designed in this study along with standardizing the method and interpreting the results showed the promising performance of this assay to differentiate the acute from the chronic stages of toxoplasmosis

Published

2026-09-12

Issue

Volume (21) issue (3)

Section

Articles