Lim Junmo, Kim Yunhwa, Hwang Ji Young, Lee Kyung Min, Park Hosun
Department of Microbiology, College of Medicine, Yeungnam University, Daegu, 42415, Republic of Korea.
Heliyon. 2024 Aug 22;10(16):e36614. doi: 10.1016/j.heliyon.2024.e36614. eCollection 2024 Aug 30.
The fluorescent antibody to membrane antigen (FAMA) test is the gold standard for measuring the immunity induced by varicella vaccines with high sensitivity and specificity. However, certain aspects of the FAMA test, such as time consumption, non-automation, and subjective interpretation by observers using fluorescence microscopy, are obstacles to handling large amounts of samples. To overcome these hurdles, flow cytometry was adopted to analyze and compare the flow FAMA titer with the classic FAMA titer. In addition, to save time in FAMA antigen preparation and reduce lot-to-lot variation, the stability of the FAMA antigen stored in liquid nitrogen was investigated. The FAMA test was performed on sera from 229 children, and antibody titers were analyzed using fluorescence microscopy (classic FAMA) and flow cytometry (flow FAMA). For comparison, glycoprotein enzyme immunoassay (gpEIA) titer was also measured. A strong correlation was found between the flow and classic FAMA titers, and the flow FAMA and gpEIA titers, with Pearson's of 0.9316 and 0.8588, respectively. Between the classic FAMA and gpEIA titers, the Pearson's value was 0.8156. The positive percent agreement, negative percent agreement, and area under the curve of the flow FAMA against classic FAMA were 95.0 %, 86.8 %, and 0.909, respectively. And those of the flow FAMA against gpEIA were 80.0 %, 87.6 %, and 0.838, respectively. The FAMA antigen stored in liquid nitrogen was stable for up to 12 months. Based on the above data, flow FAMA has the potential to be used as an alternative to classic FAMA. Moreover, pre-made FAMA antigen may reduce the preparation time and lot-to-lot variation of FAMA test.
膜抗原荧光抗体（FAMA）检测是用于测定水痘疫苗诱导的免疫的金标准，具有高灵敏度和特异性。然而，FAMA检测的某些方面，如耗时、非自动化以及观察者使用荧光显微镜进行主观判读，都是处理大量样本的障碍。为克服这些障碍，采用流式细胞术分析并比较流式FAMA滴度与经典FAMA滴度。此外，为节省FAMA抗原制备时间并减少批次间差异，研究了液氮保存的FAMA抗原的稳定性。对229名儿童的血清进行FAMA检测，使用荧光显微镜（经典FAMA）和流式细胞术（流式FAMA）分析抗体滴度。为作比较，还测定了糖蛋白酶免疫测定（gpEIA）滴度。发现流式与经典FAMA滴度之间以及流式FAMA与gpEIA滴度之间存在强相关性，Pearson相关系数分别为0.9316和0.8588。经典FAMA与gpEIA滴度之间的Pearson相关系数值为0.8156。流式FAMA相对于经典FAMA的阳性百分一致性、阴性百分一致性和曲线下面积分别为95.0%、86.8%和0.909。流式FAMA相对于gpEIA的分别为80.0%、87.6%和0.838。液氮保存的FAMA抗原在长达12个月内稳定。基于上述数据，流式FAMA有潜力作为经典FAMA的替代方法。此外，预制FAMA抗原可能会减少FAMA检测的制备时间和批次间差异。
