Meredith Scott, Puri Ankit, Majam Victoria F, Zheng Hong, Oakley Miranda S, Tonnetti Laura, Stramer Susan L, Kumar Sanjai
Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Office of Blood Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
American Red Cross Holland Laboratory, Scientific Affairs, Rockville, Maryland, USA.
Open Forum Infect Dis. 2025 May 31;12(6):ofaf253. doi: 10.1093/ofid/ofaf253. eCollection 2025 Jun.
The health burden of , the primary causative agent of human babesiosis in the United States, is significant and increasing. Diagnosis of clinical babesiosis still remains challenging, resulting in misdiagnosis and underreporting. The gold standard for detection of -specific antibody, immunofluorescence assay (IFA), is cumbersome and resource-intensive. A high-throughput assay to detect serological biomarkers of exposure would facilitate epidemiological studies and clinical diagnosis.
We developed a multiantigen, high-throughput, and highly sensitive Luminex bead-based assay (LBA) for detection of --specific antibodies in babesiosis patients and endemic populations. Serum samples from 191 individuals who had confirmed exposure (IFA or polymerase chain reaction [PCR] positive) were screened for antibody reactivity to 4 immunodominant antigens-MCFRP1, BAHCS1, SERA1, and PiβS1-by LBA.
Among the 4 antigens evaluated, MCFRP1 and BAHCS1 were the most sensitive biomarkers for exposure, detecting 96.6% and 100% of IFA+/PCR+ and 75.3% and 87.6% of IFA+/PCR- samples, respectively. The "window period" before IFA-detectable seroconversion is of particular concern for clinical diagnosis using serological detection methods. Importantly, combining all 4 antigens allowed detection of 6/13 (46.2%) PCR-positive cases that were missed by IFA. No single antigen yielded reactivity to more than 3/13 (23.1%) IFA-/PCR+ cases in our LBA, indicating diversity in the polarization of early immune responses following exposure.
Combination of these antigens in our LBA would reduce the window period before IFA-detectable seroconversion of detection in -exposed individuals.
在美国，作为人类巴贝斯虫病的主要病原体，其健康负担巨大且呈上升趋势。临床巴贝斯虫病的诊断仍然具有挑战性，导致误诊和报告不足。检测特定抗体的金标准——免疫荧光测定法（IFA）繁琐且资源消耗大。一种用于检测暴露血清生物标志物的高通量检测方法将有助于流行病学研究和临床诊断。
我们开发了一种基于Luminex微球的多抗原、高通量且高灵敏度的检测方法（LBA），用于检测巴贝斯虫病患者和流行地区人群中的特定抗体。通过LBA对191名已确认暴露（IFA或聚合酶链反应[PCR]阳性）个体的血清样本进行筛查，以检测其对4种免疫显性抗原——MCFRP1、BAHCS1、SERA1和PiβS1的抗体反应性。
在评估的4种抗原中，MCFRP1和BAHCS1是暴露的最敏感生物标志物，分别检测出96.6%和100%的IFA+/PCR+样本以及75.3%和87.6%的IFA+/PCR-样本。对于使用血清学检测方法进行临床诊断而言，IFA可检测到血清转化之前的“窗口期”尤为值得关注。重要的是，将所有4种抗原结合使用能够检测出6/13（46.2%）IFA遗漏的PCR阳性病例。在我们的LBA中，没有单一抗原对超过3/13（23.1%）的IFA-/PCR+病例产生反应性，这表明暴露后早期免疫反应的极化存在多样性。
在我们的LBA中使用这些抗原的组合将缩短暴露个体中IFA可检测到血清转化之前的窗口期。
