严重发热伴血小板减少综合征(SFTS)是由SFTS病毒(SFTSV)引起的。我们调查了SFTS患者血清学反应的详细动力学。2015年7月至2018年10月纳入28例年龄≥18岁的患者。通过使用逆转录聚合酶链反应检测其血浆中的SFTSVRNA来确认SFTS。使用免疫荧光测定(IFA)和酶联免疫吸附测定(ELISA)测量SFTSV特异性IgG和IgM。我们发现在症状发作后第5-9天检测到SFTSV特异性IgG,在疾病过程中,它的滴度在上升。SFTSV特异性IgM滴度在症状发作的第2-3周左右达到峰值。使用IFA和ELISA,症状发作后第5-9、10-14、15-19和20-24天的SFTSV特异性血清阳性率为63%,76%,90%,100%,58%,86%,100%,100%,分别,对于IgG,而他们是32%,62%,80%,100%,53%,62%,70%,100%,分别,IgM。延迟的IgM应答可归因于SFTSV特异性IgMIFA或ELISA的低敏感性和/或受损的免疫应答。我们在这项研究中使用的使用IFA或ELISA的IgM测试是,因此,不足以早期诊断SFTS。
Severe fever with thrombocytopenia syndrome (SFTS) is caused by SFTS virus (SFTSV). We investigated the detailed kinetics of serologic response in patients with SFTS. Twenty-eight patients aged ≥18 years were enrolled between July 2015 and October 2018. SFTS was confirmed by detecting SFTSV RNA in their plasma using reverse transcription polymerase chain reaction. SFTSV-specific IgG and IgM were measured using immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA). We found that SFTSV-specific IgG was detected at days 5-9 after symptom onset, and its titer was rising during the course of disease. SFTSV-specific IgM titer peaked at around week 2-3 from symptom onset. The SFTSV-specific seropositive rates for days 5-9, 10-14, 15-19, and 20-24 from symptom onset using IFA and ELISA were 63%, 76%, 90%, and 100%, and 58%, 86%, 100%, and 100%, respectively, for IgG, whereas they were 32%, 62%, 80%, and 100%, and 53%, 62%, 70%, and 100%, respectively, for IgM. The delayed IgM response could be attributed to the low sensitivity of SFTSV-specific IgM IFA or ELISA and/or impaired immune responses. The IgM test using IFA or ELISA that we used in this study is, therefore, insufficient for the early diagnosis of SFTS.