Coronavirus-specific saliva IgA assay
IgA
CORONAVIRUS
Saliva samples were collected by centrifugation after having each subject spit about 2 mL of saliva into a disposable saliva sample collector (HUAXIA Medical Equipment). Coronavirus-specific IgA was tested with a SARS-CoV-2 specific (COVID-19 Coronavirus Panel 2) Mesoscale Discovery (MSD) immunoassay. According to the manufacturer’s instructions, plates were blocked, washed, and incubated with diluted saliva samples. After incubation with the detection antibody, plates were read on a Meso QuickPlex instrument. IgA concentrations were showed in arbitrary units (AU) per ml as calculated from a standard curve supplied with the kit. To minimize the variability of mucosal sampling, saliva samples were normalized via an enzyme-linked immunosorbent assay for quantitative detection of human IgA using a commercial kit (Invitrogen) as described previously (