Molecular Biology Section, Department of Biology, Faculty of Science, Ege University, İzmir, Turkey.
Vaccine Development, Application and Research Center, Ege University, İzmir, Turkey.
BMC Infect Dis. 2022 Jan 31;22(1):110. doi: 10.1186/s12879-022-07088-w.
Discovery of new Toxoplasma gondii serotyping epitopes is important due to reports showing the influence of genotype on the severity of toxoplasmosis. In Turkey, genotypes belonging to type II, type III and Africa 1 lineages were mainly detected. The present study focused on to find out epitopes with high discriminative capacity to serotype these genotypes using well characterized strains isolated from Turkey.
To meet this objective, GRA6 and GRA7 genes were sequenced from strains belonging to the type II, III and Africa 1 lineages, and B cell epitopes inside these sequences were predicted by Bcepred and additional docking analysis was performed with B cell receptor. Based on these analyses, 22 peptides harboring lineage specific epitopes were synthesized. Then, the serotyping potency of these peptides was tested using peptide ELISA and well categorized serum samples collected from stray cats infected with genotypes of the different lineages type II (n:9), III (n:1) and Africa 1 (n:1). As a result of peptide-ELISA, a serotyping schema was constructed with peptides that show high discriminative capacity and this assay was validated by sera collected from humans after an outbreak (n:30) and mother/newborn pair sera (n:3). Later, the validated serotyping schema was used to serotype a larger group of human (n:38) and cat (n:24) sera.
Among 22 peptides, GRA6II/c, GRA7III/d, and GRA6 Africa 1/b epitopes have shown discriminative capacity. During the validation of peptide-ELISA, the serotype of toxoplasmosis outbreak and mother/newborn cases were detected to be serotype II. Moreover, the analyses in a larger group showed that serotype II was prevalent in humans and stray cats.
Overall, the results showed that the serotyping schema could be successfully used to serotype T. gondii infections caused by type II, III and Africa 1 genotype.
由于有报道称基因型会影响弓形虫病的严重程度，因此发现新的弓形虫血清型表位很重要。在土耳其，主要检测到属于 II 型、III 型和非洲 1 谱系的基因型。本研究旨在使用从土耳其分离的特征良好的菌株发现具有高区分能力的表位来对这些基因型进行血清分型。
为了达到这个目的，对属于 II 型、III 型和非洲 1 谱系的菌株进行了 GRA6 和 GRA7 基因测序，并通过 Bcepred 预测了这些序列中的 B 细胞表位，并用 B 细胞受体进行了额外的对接分析。基于这些分析，合成了 22 个含有谱系特异性表位的肽。然后，使用肽 ELISA 测试了这些肽的血清分型能力，并使用来自感染不同谱系基因型的流浪猫的血清样本进行了测试（II 型 n:9、III 型 n:1 和非洲 1 型 n:1）。肽 ELISA 的结果构建了一个具有高区分能力的肽的血清分型方案，并通过暴发后收集的人类血清（n:30）和母婴血清（n:3）进行了验证。随后，使用验证后的血清分型方案对更大的人类（n:38）和猫（n:24）血清进行了血清分型。
在 22 个肽中，GRA6II/c、GRA7III/d 和 GRA6 Africa 1/b 表位具有区分能力。在肽 ELISA 的验证过程中，发现暴发和母婴病例的血清型为 II 型。此外，在更大的人群分析中发现，II 型在人类和流浪猫中更为流行。
总的来说，结果表明该血清分型方案可成功用于 II 型、III 型和非洲 1 型基因型引起的弓形虫感染的血清分型。
