Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
J Infect Dis. 2020 Nov 13;222(12):1974-1984. doi: 10.1093/infdis/jiaa581.
Convalescent plasma therapy is a leading treatment for conferring temporary immunity to COVID-19-susceptible individuals or for use as post-exposure prophylaxis. However, not all recovered patients develop adequate antibody titers for donation and the relationship between avidity and neutralizing titers is currently not well understood.
SARS-CoV-2 anti-spike and anti-nucleocapsid IgG titers and avidity were measured in a longitudinal cohort of COVID-19 hospitalized patients (n = 16 individuals) and a cross-sectional sample of convalescent plasma donors (n = 130). Epidemiologic correlates of avidity were examined in donors by linear regression. The association of avidity and a high neutralizing titer (NT) were also assessed in donors using modified Poisson regression.
Antibody avidity increased over duration of infection and remained elevated. In convalescent plasma donors, higher levels of anti-spike avidity were associated with older age, male sex, and hospitalization. Higher NTs had a stronger positive correlation with anti-spike IgG avidity (Spearman ρ = 0.386; P < .001) than with anti-nucleocapsid IgG avidity (Spearman ρ = 0.211; P = .026). Increasing levels of anti-spike IgG avidity were associated with high NT (≥160) (adjusted prevalence ratio = 1.58 [95% confidence interval = 1.19-2.12]), independent of age, sex, and hospitalization.
SARS-CoV-2 antibody avidity correlated with duration of infection and higher neutralizing titers, suggesting a potential alternative screening parameter for identifying optimal convalescent plasma donors.
恢复期血浆疗法是为 COVID-19 易感个体提供临时免疫力或用作暴露后预防的主要治疗方法。然而，并非所有康复患者都能产生足够用于捐献的抗体滴度，且目前人们对亲和力与中和滴度之间的关系还不甚了解。
我们对 COVID-19 住院患者（n=16 人）的纵向队列和恢复期血浆捐献者（n=130 人）的横断面样本进行了 SARS-CoV-2 刺突蛋白和核衣壳 IgG 滴度和亲和力的测量。通过线性回归对捐献者的亲和力相关的流行病学因素进行了检查。还使用校正泊松回归对捐献者的亲和力与高中和滴度（NT）之间的关联进行了评估。
抗体亲和力随感染时间的延长而增加，并持续升高。在恢复期血浆捐献者中，较高的刺突蛋白亲和力与年龄较大、男性和住院治疗有关。较高的 NT 与抗刺突 IgG 亲和力呈更强的正相关（Spearman ρ=0.386；P<0.001），与抗核衣壳 IgG 亲和力呈更强的正相关（Spearman ρ=0.211；P=0.026）。抗刺突 IgG 亲和力的升高与高 NT（≥160）有关（校正后患病率比=1.58[95%置信区间 1.19-2.12]），与年龄、性别和住院治疗无关。
SARS-CoV-2 抗体亲和力与感染持续时间和更高的中和滴度相关，这表明识别最佳恢复期血浆捐献者的潜在替代筛选参数。
