OBJECTIVES The long-term dynamics of antibody responses in patients with influenza A(H7N9) virus infection are not well understood. METHODS We conducted a longitudinal serological follow-up study in patients who were hospitalized with A(H7N9) virus infection, during 2013-2018. A(H7N9) virus-specific antibody responses were assessed by hemagglutination inhibition (HAI) and neutralization (NT) assays. A random intercept model was used to fit a curve to HAI antibody responses over time. HAI antibody responses were compared by clinical severity. RESULTS Of 67 patients with A(H7N9) virus infection, HAI antibody titers reached 40 on average 11 days after illness onset and peaked at a titer of 290 after three months, and average titers of ≥80 and ≥40 were present until 11 months and 22 months respectively. HAI antibody responses were significantly higher in patients who experienced severe disease, including respiratory failure and acute respiratory distress syndrome, compared with patients who experienced less severe illness. CONCLUSIONS Patients with A(H7N9) virus infection who survived severe disease mounted higher antibody responses that persisted for longer periods compared with those that experienced moderate disease. Studies of convalescent plasma treatment for A(H7N9) patients should consider collection of donor plasma from survivors of severe disease between 1 and 11 months after illness onset.

中文翻译：

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人体对甲型禽流感 (H7N9) 病毒感染的抗体反应的特异性、动力学和寿命。

目的 甲型 H7N9 流感病毒感染患者抗体反应的长期动态尚不清楚。方法 我们对 2013 年至 2018 年期间因甲型 H7N9 病毒感染住院的患者进行了纵向血清学随访研究。通过血凝抑制 (HAI) 和中和 (NT) 测定评估 A(H7N9) 病毒特异性抗体反应。使用随机截距模型来拟合 HAI 抗体随时间反应的曲线。根据临床严重程度比较 HAI 抗体反应。结果 67例甲型H7N9病毒感染患者，发病后11天HAI抗体滴度平均达到40，3个月后达到峰值290，平均滴度≥80和≥40持续到11个月，分别为22个月。与病情较轻的患者相比，患有严重疾病（包括呼吸衰竭和急性呼吸窘迫综合征）的 HAI 抗体反应明显更高。结论 与患有中度疾病的患者相比，感染 A(H7N9) 病毒的患者在重症后幸存下来的抗体反应更高，且持续时间更长。对 A(H7N9) 患者恢复期血浆治疗的研究应考虑在发病后 1 至 11 个月内从严重疾病幸存者中收集供体血浆。