Betancourt Angelis Del Valle Benitez, Silva Tamires Lopes, de Freitas Oliveira Débora Karolla, Nicolau-Junior Nilson, Garcia João Luis, Fujiwara Ricardo Toshio, Mineo Tiago Wilson Patriarca, Mineo José Roberto
Laboratory of Immunoparasitology Dr. Mario Endsfeldz Camargo, Institute of Biomedical Sciences, Federal University of Uberlandia, Uberlândia 38400-902, MG, Brazil.
Laboratory of Molecular Modeling, Institute of Biotechnology, Federal University of Uberlandia, Uberlândia 38400-902, MG, Brazil.
Int J Mol Sci. 2025 May 14;26(10):4689. doi: 10.3390/ijms26104689.
Toxoplasmosis is a widely spread zoonosis worldwide, considered one of the most important parasitic infections that affect global public health, and usually, it is not correctly diagnosed. Serological tests for the diagnosis of infection have limitations in differentiating acute from chronic infection, which is important to determine the appropriate clinical management and treatment, mainly in pregnant women and immunocompromised individuals infected by this parasite. The present study aimed to characterize immunogenic epitopes from immunodominant antigens, as SAG1(SRS29B), SAG2A (SRS34A), GRA1, GRA2, GRA3, GRA5, GRA6, GRA7, MAG1, BSR4, and CCp5A, by investigating if these parasite components might emerge as alternatives to improve the diagnosis of toxoplasmosis. A detailed comparative in silico analysis was used for this purpose. Once the protein sequences were retrieved from the ToxoDB database, different parameters were calculated, including physicochemical characteristics, accessibility values, and antigenicity. Multiple sequence alignment, 3D structures modeling, and the validation of 3D structures were also performed among all 11 peptides. Considering the results from the combination of all parameters analyzed, it can be hypothesized that the linear epitopes from SAG1, GRA3, and BSR4 proteins were found to be stable and hydrophilic, with a significant antigenicity score, and accessibility on the protein surface. Also, these three selected peptides were able to detect anti- antibodies in serum samples from pigs infected by tachyzoites, when compared with control serum samples, obtained from the same naïve animals and tested by ELISA, demonstrating remarkable difference in terms of reactivity. Taken together, as our study addresses a critical challenge in the serodiagnosis of toxoplasmosis, particularly in gestational and congenital infections, where false-positive and false-negative results often arise from the use of native or recombinant antigens of , our findings highlight the potential of synthetic peptides derived from novel epitopes of this parasite as alternative tools for the development of more accurate immunodiagnostic assays for toxoplasmosis.
弓形虫病是一种在全球广泛传播的人畜共患病，被认为是影响全球公共卫生的最重要的寄生虫感染之一，而且通常无法得到正确诊断。用于诊断感染的血清学检测在区分急性感染和慢性感染方面存在局限性，而这对于确定适当的临床管理和治疗至关重要，尤其是对于感染该寄生虫的孕妇和免疫功能低下者。本研究旨在通过研究这些寄生虫成分是否可能成为改善弓形虫病诊断的替代方法，来表征免疫显性抗原（如SAG1(SRS29B)、SAG2A (SRS34A)、GRA1、GRA2、GRA3、GRA5、GRA6、GRA7、MAG1、BSR4和CCp5A）的免疫原性表位。为此使用了详细的计算机模拟比较分析。一旦从ToxoDB数据库中检索到蛋白质序列，就会计算不同的参数，包括物理化学特性、可及性值和抗原性。还对所有11种肽进行了多序列比对、三维结构建模和三维结构验证。综合所有分析参数的结果，可以推测SAG1、GRA3和BSR4蛋白的线性表位是稳定且亲水性的，具有显著的抗原性评分，并且在蛋白质表面具有可及性。此外，与从相同未感染动物获得并通过ELISA检测的对照血清样本相比，这三种选定的肽能够在速殖子感染猪的血清样本中检测到抗体，在反应性方面显示出显著差异。综上所述，由于我们的研究解决了弓形虫病血清学诊断中的一个关键挑战，特别是在妊娠和先天性感染中，使用该寄生虫的天然或重组抗原常常会出现假阳性和假阴性结果，我们的研究结果突出了源自该寄生虫新表位的合成肽作为开发更准确的弓形虫病免疫诊断检测方法的替代工具的潜力。
