Detection of cross-reactive immunoglobulin A against the severe acute respiratory syndrome-coronavirus-2 spike 1 subunit in saliva

• DOI: 10.1371/journal.pone.0249979
• Publication Date: 2021-11-23T20:09:51Z
• Authors: Keiichi Tsukinoki; Tatsuo Yamamoto; Keisuke Handa; Mariko Iwamiya; Juri Saruta; Satoshi Ino; Takashi Sakurai
• Keywords: Immunoglobulin A; Coronavirus

Abundant secretory immunoglobulin A (SIgA) in the mucus, breast milk, and saliva provides immunity against infection of mucosal surfaces. Pre-pandemic milk samples containing SIgA have been reported to cross-react with SARS-CoV-2; however, it remains unknown whether showing cross-reaction SARS-CoV-2 exists saliva. We aimed clarify cross-reacts spike 1 subunit individuals who not infected this virus. The study involved 137 (men, n = 101; women, 36; mean age, 38.7; age range, 24-65 years) dentists doctors from Kanagawa Dental University Hospital. Saliva blood were analyzed by polymerase chain reaction (PCR) immunochromatography for IgG IgM, respectively. then identified patients that confirmed be PCR-negative IgM-negative SARS-CoV-2. cross-reactivity IgA-positive was determined enzyme-linked immunosorbent assay using a biotin-labeled recombinant protein (S1-mFc) covering receptor-binding domain proportion cross-reactive 46.7%, which correlated negatively (r -0.218, p 0.01). aged ≥50 years significantly lower than ≤49 (p 0.008). purified patients, could partially suppress binding angiotensin converting enzyme-2 receptor. This demonstrates presence had never virus, suggesting may help prevent infection.