Saliva as a useful tool for evaluating upper mucosal antibody response to influenza

• Published in: PloS one Vol. 17; no. 2; p. e0263419
• Main Authors: Tsunetsugu-Yokota, Yasuko, Ito, Sayaka, Adachi, Yu, Onodera, Taishi, Kageyama, Tsutomu, Takahashi, Yoshimasa
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.02.2022; Public Library of Science (PLoS)
• Subjects: Adult; Aged; Antibodies; Antibodies, Viral - analysis; Antibodies, Viral - metabolism; Antibody Formation; Antibody response; Asymptomatic; Biology and Life Sciences; Cohort Studies; Coronaviruses; COVID-19 vaccines; Diagnosis; Disease transmission; Evaluation; Female; History, 21st Century; Humans; Immunity; Immunity, Mucosal - physiology; Immunoglobulin A; Immunoglobulin A - analysis; Immunoglobulin A - metabolism; Immunoglobulin A, Secretory - analysis; Immunoglobulin A, Secretory - metabolism; Immunoglobulin G; Immunoglobulin G - analysis; Immunoglobulin G - metabolism; Infections; Infectious diseases; Influenza; Influenza A; Influenza A Virus, H1N1 Subtype - immunology; Influenza Vaccines - therapeutic use; Influenza, Human - diagnosis; Influenza, Human - immunology; Influenza, Human - prevention & control; Japan; Longitudinal Studies; Male; Medical technology; Medicine and Health Sciences; Mucosal immunity; Pandemics; Predictive Value of Tests; Prevention; Prognosis; Properties; Research and Analysis Methods; Saliva; Saliva - chemistry; Saliva - immunology; Saliva - metabolism; Salivary glands; Seasons; secretions; Serology; Severe acute respiratory syndrome coronavirus 2; Vaccines; Viral antibodies; Viruses; Young Adult; Japan; United States > US; Singapore
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0263419

Mucosal immunity plays a crucial role in controlling upper respiratory infections, including influenza. We established a quantitative ELISA to measure the amount of influenza virus-specific salivery IgA (sIgA) and salivary IgG (sIgG) antibodies using a standard antibody broadly reactive to the influenza A virus. We then analyzed saliva and serum samples from seven individuals infected with the A(H1N1)pdm09 influenza virus during the 2019–2020 flu seasons. We detected an early (6–10 days post-infection) increase of sIgA in five of the seven samples and a later (3–5 weeks) increase of sIgG in six of the seven saliva samples. Although the conventional parenteral influenza vaccine did not induce IgA production in saliva, vaccinated individuals with a history of influenza infection had higher basal levels of sIgA than those without a history. Interestingly, we observed sIgA and sIgG in an asymptomatic individual who had close contact with two influenza cases. Both early mucosal sIgA secretion and late systemically induced sIgG in the mucosal surface may protect against virus infection. Despite the small sample size, our results indicate that the saliva test system can be useful for analyzing upper mucosal immunity in influenza.