Department of Dental Medicine, Karolinska Institutet, Stockholm, Sweden.
Department of Protein Science, Division of Affinity Proteomics, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SciLifeLab, Stockholm, Sweden.
J Infect Dis. 2021 Aug 2;224(3):407-414. doi: 10.1093/infdis/jiab256.
Declining humoral immunity in coronavirus disease 2019 (COVID-19) patients and possible reinfection have raised concern. Mucosal immunity, particularly salivary antibodies, may be short lived although long-term studies are lacking.
Using a multiplex bead-based array platform, we investigated antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins in 256 saliva samples from convalescent patients 1-9 months after symptomatic COVID-19 (n = 74, cohort 1), undiagnosed individuals with self-reported questionnaires (n = 147, cohort 2), and individuals sampled prepandemic (n = 35, cohort 3).
Salivary IgG antibody responses in cohort 1 (mainly mild COVID-19) were detectable up to 9 months postrecovery, with high correlations between spike and nucleocapsid specificity. At 9 months, IgG remained in blood and saliva in most patients. Salivary IgA was rarely detected at this time point. In cohort 2, salivary IgG and IgA responses were significantly associated with recent history of COVID-19-like symptoms. Salivary IgG tolerated temperature and detergent pretreatments.
Unlike SARS-CoV-2 salivary IgA that appeared short lived, specific saliva IgG appeared stable even after mild COVID-19, as for blood serology. This noninvasive saliva-based SARS-CoV-2 antibody test with home self-collection may be a complementary alternative to conventional blood serology.
新冠肺炎（COVID-19）患者的体液免疫下降和可能再次感染引起了关注。尽管缺乏长期研究，但黏膜免疫，特别是唾液抗体可能持续时间较短。
使用基于多重微珠的阵列平台，我们检测了 256 份来自 COVID-19 症状缓解后 1-9 个月的恢复期患者（n=74，队列 1）、有自我报告问卷的未确诊个体（n=147，队列 2）和流行前采样个体（n=35，队列 3）的唾液中针对严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）蛋白的特异性抗体。
队列 1（主要为轻症 COVID-19）的唾液 IgG 抗体反应可在康复后 9 个月内检测到，刺突蛋白和核衣壳蛋白特异性之间具有高度相关性。9 个月时，大多数患者的血液和唾液中仍存在 IgG。此时很少检测到唾液 IgA。在队列 2 中，唾液 IgG 和 IgA 反应与近期 COVID-19 样症状史显著相关。唾液 IgG 可耐受温度和去污剂预处理。
与 SARS-CoV-2 唾液 IgA 短暂存在不同，即使是轻度 COVID-19 后，特异性唾液 IgG 也似乎很稳定，就像血液血清学一样。这种具有家庭自我采集功能的非侵入性 SARS-CoV-2 抗体唾液检测可能是传统血液血清学的补充替代方法。
