Data_Sheet_1_In the Search of Potential Serodiagnostic Proteins to Discriminate Between Acute and Chronic Q Fever in Humans. Some Promising Outcomes.docx

Coxiella burnetii is the agent that causes acute and chronic Q fever infections in humans. Although the isolates studied so far have shown that the two forms of the disease differ in virulence potential thus, implying a variance in their proteomic profile, the methods used do not deliver enough discriminatory capability and often, human infections may be mis-diagnosed. The current study adds further knowledge to the results that we have already published on the Coxiella outer membrane protein 1 (Com1). Herein we identified the proteins GroEL, Ybgf, OmpH, and UPF0422 as candidates for serodiagnostics of Q fever; following cloning, expression and purification they were further used as antigens in ELISA for the screening of patients' sera associated with chronic Q fever endocarditis, sera negative for phase I IgG, sera with at least one sample positive for phase I IgG and sera from patients who suffered from various rheumatic diseases. Blood donors were used as the controls. Sensitivity, specificity, positive predictive value, negative predictive value, and Cohen's kappa coefficient (κ) were calculated and we also performed binary logistic regression analysis to identify combinations of proteins with increased diagnostic yield. We found that proteins GroEL and Ybgf, together with Com1, play the most significant role in the correct diagnosis of chronic Q fever. Of these three proteins, it was shown that Com1 and GroEL present the highest sensitivity and specificity altogether. The results add to the existing knowledge that an antigen-based serodiagnostic test that will be able to correctly diagnose chronic Q fever may not be far from reality.

Q热病原体为考克斯体伯内特ii型，其可致人类急性及慢性Q热感染。尽管迄今为止的研究表明，该病的两种形式在致病潜力上存在差异，从而暗示其蛋白质组谱存在变异，但所采用的方法尚无法提供足够的区分能力，且在许多情况下，人类感染可能被误诊。本研究进一步丰富了我们对已发表的考克斯体外膜蛋白1（Com1）相关成果的认识。在此，我们鉴定了GroEL、Ybgf、OmpH和UPF0422蛋白作为Q热血清学诊断的候选蛋白；经过克隆、表达和纯化后，这些蛋白被进一步用作抗原，在酶联免疫吸附测定（ELISA）中用于筛选与慢性Q热心内膜炎相关的患者血清、I期IgG阴性的血清、至少一个样本I期IgG阳性的血清，以及患有各种风湿性疾病的患者的血清。献血者作为对照组。计算了灵敏度、特异性、阳性预测值、阴性预测值和Cohen's κ系数（κ），并进行了二元逻辑回归分析，以确定具有提高诊断效率的蛋白组合。我们发现，GroEL和Ybgf蛋白与Com1蛋白一起，在慢性Q热的准确诊断中发挥着最为显著的作用。在这三种蛋白中，Com1和GroEL共同表现出最高的灵敏度和特异性。这些结果进一步证实，基于抗原的血清学诊断测试，能够准确诊断慢性Q热，这一现实可能指日可待。