Background. The specificity and duration of circulating human antibody-secreting cells (ASCs) after vaccination have been well described, but characteristics of ASCs during acute respiratory infections have not been well studied.

Methods. Circulating antigen-specific ASCs were measured at 3 time points (enrollment, days 10–16, and days 22–45) in 40 adults during respiratory syncytial virus (RSV) infection.

Results. Of the 40 patients, 36 (90%) had detectable circulating RSV F protein-specific ASCs within 11 days after illness onset. The magnitude of the RSV-specific ASCs was 1–1500 spots per 10 ⁶peripheral blood mononuclear cells (mean frequency [± standard deviation], 200 ± 256 spots per 10⁶ peripheral blood mononuclear cells). ASCs were detected on day 8–16 and day 22–45 after symptom onset in 78% and 48% of subjects, respectively. Subjects shedding virus for >10 days were more likely to have a positive response to ASC enzyme-linked immunospot assay at the late time point than those shedding for ⩽10 days (8 of 12 subjects vs 2 of 11 subjects; P = .02).

Conclusions. The kinetics of ASC circulation during acute mucosal viral infections was more prolonged than that we had observed after a single intramuscular injection with inactivated influenza vaccine in a study reported elsewhere. The association between the duration of virus shedding and the persistence of detectable viral-specific ASCs suggests that ongoing antigen persistence induces a prolonged temporal pattern of ASC generation.