Abstract：
Immunoglobulin G (IgG) and immunoglobulin M (IgM) testing are commonly used to determine infection status. Typically, the detection of IgM indicates an acute or recent infection, while the presence of IgG alone suggests a chronic or past infection. However, relying solely on IgG and IgM antibody positivity may not be sufficient to differentiate acute from chronic infections. This limitation arises from several factors. The prolonged presence of IgM can complicate diagnostic interpretations, and false positive IgM results often arise from antibody cross-reactivity with various antigens. Additionally, IgM may remain undetectable in prematurely collected samples or in individuals who are immunocompromised, further complicating accurate diagnosis. As a result, additional diagnostic tools are required to confirm infection status. Avidity is a measure of the strength of the binding between an antigen and antibody. Avidity-based assays have been developed for various infectious agents, including toxoplasma, cytomegalovirus (CMV), SARS-CoV-2, and avian influenza, and are promising tools in clinical diagnostics. By measuring the strength of antibody binding, they offer critical insights into the maturity of the immune response. These assays are instrumental in distinguishing between acute and chronic or past infections, monitoring disease progression, and guiding treatment decisions. The development of automated platforms has optimized the testing process by enhancing efficiency and minimizing the risk of manual errors. Additionally, the recent advent of real-time biosensor immunoassays, including the label-free immunoassays (LFIA), has further amplified the capabilities of these assays. These advances have expanded the clinical applications of avidity-based assays, making them useful tools for the diagnosis and management of various infectious diseases. This review is structured around several key aspects of IgG avidity in clinical diagnosis, including: (i) a detailed exposition of the IgG affinity maturation process; (ii) a thorough discussion of the IgG avidity assays, including the recently emerged biosensor-based approaches; and (iii) an examination of the applications of IgG avidity in clinical diagnosis. This review is intended to contribute toward the development of enhanced diagnostic tools through critical assessment of the present landscape of avidity-based testing, which allows us to identify the existing knowledge gaps and highlight areas for future investigation.
摘要：
免疫球蛋白G（IgG）和免疫球蛋白M（IgM）测试通常用于确定感染状态。通常,IgM的检测表明急性或近期感染，而单独的IgG的存在表明慢性或过去的感染。然而,仅依靠IgG和IgM抗体阳性可能不足以区分急性和慢性感染.这种限制是由几个因素引起的。IgM的长期存在会使诊断解释复杂化，假阳性IgM结果通常是由于抗体与各种抗原的交叉反应性。此外,IgM可能在过早收集的样本或免疫功能低下的个体中检测不到。进一步复杂的准确诊断。因此,需要额外的诊断工具来确认感染状态.亲合力是抗原和抗体之间结合强度的量度。已经针对各种感染因子开发了基于亲和力的检测方法，包括弓形虫,巨细胞病毒（CMV），SARS-CoV-2和禽流感,并且是临床诊断中很有前途的工具。通过测量抗体结合的强度，它们为免疫反应的成熟提供了重要的见解。这些测定有助于区分急性和慢性或过去的感染，监测疾病进展，指导治疗决策。自动化平台的开发通过提高效率和最小化手动错误的风险来优化测试过程。此外,最近出现的实时生物传感器免疫测定，包括无标签免疫测定（LFIA），进一步放大了这些测定的能力。这些进展扩大了基于亲合力的检测的临床应用,使它们成为诊断和管理各种传染病的有用工具。这篇综述围绕临床诊断中IgG亲和力的几个关键方面进行。包括：（i）详细阐述IgG亲和力成熟过程；（ii）彻底讨论IgG亲和力测定，包括最近出现的基于生物传感器的方法;和(iii)检查IgG亲合力在临床诊断中的应用。本文旨在通过对基于亲合力的测试的现状进行严格评估，为开发增强的诊断工具做出贡献。这使我们能够确定现有的知识差距，并突出未来调查的领域。
