posted on 2021-12-22, 17:04authored byZheyu Wang, Jeremiah J. Morrissey, Lin Liu, Yixuan Wang, Qingjun Zhou, Rajesh R. Naik, Srikanth Singamaneni
Severe
acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has
rapidly spread and resulted in the global pandemic of COVID-19. Although
IgM/IgG serology assay has been widely used, with the entire spike
or nucleocapsid antigens, they only indicate the presence or absence
of antibodies against these proteins but are not specific to the neutralization
antibodies, therefore providing only generic information about infection
stage and possible future immune protection. Novel technologies enabling
easy-to-use and sensitive detection of multiple specific antibodies
simultaneously will facilitate precise diagnosis of infection stage,
prediction of clinical outcomes, and evaluation of future immune protection
upon viral exposure or vaccination. Here, we demonstrate a rapid and
ultrasensitive quantification method for epitope-specific antibodies,
including different isotypes and subclasses, in a multiplexed manner.
Using an ultrabright fluorescent nanolabel, plasmonic-fluor, this
novel assay can be completed in 20 min and more importantly, the limit
of detection of the plasmon-enhanced immunoassay for SARS-CoV-2 antibodies
is as much as 100-fold lower compared to the assays relying on enzymatic
amplification of colorimetric signals. Using convalescent patient
plasma, we demonstrate that this biodetection method reveals the patient-to-patient
variability in immune response as evidenced by the variations in whole
protein and epitope-specific antibodies. This cost-effective, rapid,
and ultrasensitive plasmonically enhanced multiplexed epitope-specific
serological assay has the potential to be broadly employed in the
detection of specific antibodies, which may benefit the advanced epidemiology
studies and enable improvement of the clinical outcomes and prediction
of the future protection against the SARS-CoV-2.