Department of Biochemistry, University of Oxford, Oxford, UK.
Lao-Oxford-Mahosot Hospital-Wellcome Trust-Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR.
Trans R Soc Trop Med Hyg. 2022 Nov 1;116(11):1032-1042. doi: 10.1093/trstmh/trac036.
The mainstay of diagnostic confirmation of acute Japanese encephalitis (JE) involves detection of anti-JE virus (JEV) immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA). Limitations in the specificity of this test are increasingly apparent with the introduction of JEV vaccinations and the endemicity of other cross-reactive flaviviruses. Virus neutralization testing (VNT) is considered the gold standard, but it is challenging to implement and interpret. We performed a pilot study to assess IgG depletion prior to VNT for detection of anti-JEV IgM neutralizing antibodies (IgM-VNT) as compared with standard VNT.
We evaluated IgM-VNT in paired sera from anti-JEV IgM ELISA-positive patients (JE n=35) and negative controls of healthy flavivirus-naïve (n=10) as well as confirmed dengue (n=12) and Zika virus (n=4) patient sera. IgM-VNT was subsequently performed on single sera from additional JE patients (n=76).
Anti-JEV IgG was detectable in admission serum of 58% of JE patients. The positive, negative and overall percentage agreement of IgM-VNT as compared with standard VNT was 100%. A total of 12/14 (86%) patient samples were unclassified by VNT and, with sufficient sample available for IgG depletion and IgG ELISA confirming depletion, were classified by IgM-VNT. IgM-VNT enabled JE case classification in 72/76 (95%) patients for whom only a single sample was available.
The novel approach has been readily adapted for high-throughput testing of single patient samples and it holds promise for incorporation into algorithms for use in reference centres.
急性日本脑炎（JE）的诊断确认主要依赖酶联免疫吸附试验（ELISA）检测抗日本脑炎病毒（JEV）免疫球蛋白 M（IgM）。随着 JEV 疫苗的引入和其他交叉反应性黄病毒的地方性流行，该检测的特异性局限性日益明显。病毒中和试验（VNT）被认为是金标准，但实施和解释具有挑战性。我们进行了一项试点研究，评估 VNT 前 IgG 耗竭检测抗 JEV IgM 中和抗体（IgM-VNT）与标准 VNT 的比较。
我们评估了抗 JEV IgM ELISA 阳性患者（JE n=35）和健康无黄病毒史的阴性对照（n=10）以及确诊登革热（n=12）和寨卡病毒（n=4）患者血清的 IgM-VNT。随后对额外的 JE 患者（n=76）进行了单次血清 IgM-VNT。
58%的 JE 患者入院时可检测到抗 JEV IgG。与标准 VNT 相比，IgM-VNT 的阳性、阴性和总符合率为 100%。共有 12/14（86%）患者的 VNT 结果无法分类，在有足够样本进行 IgG 耗竭和 IgG ELISA 确认耗竭的情况下，通过 IgM-VNT 进行分类。IgM-VNT 可对 72/76（95%）只有单一样本的患者进行 JE 病例分类。
这种新方法已易于适应高通量检测单个患者样本，并有望纳入参考中心使用的算法。
