A rapid test recognizing mucosal SARS-CoV-2-specific antibodies distinguishes prodromal from convalescent COVID-19

Abstract

The COVID-19 pandemic poses enormous challenges to global healthcare sectors. To prevent the overburden of medical systems, it is crucial to distinguish individuals approaching the most infectious early phase from those in the declining non-infectious phase. However, a large fraction of transmission events occur during pre- or asymptomatic phases. Especially in absence of symptoms, it is difficult to distinguish prodromal from late phases of infection just by RT-PCR since both phases are characterized by low viral loads and corresponding high Ct values (>30). We evaluated a new rapid test detecting IgG antibodies recognizing SARS-CoV-2 nucleocapsid protein using two commercial antibody assays and an in-house neutralization test before determining suitability for testing clinical swab material. Our analyses revealed the combination of the well-known RT-PCR and the new rapid antibody test using one single clinical nasopharyngeal swab specimen as fast, cost-effective, and reliable way to discriminate prodromal from subsiding phases of COVID-19.

A colorimetric lateral flow immunoassay based on oriented antibody immobilization for sensitive detection of SARS-CoV-2

“…As the BC domains of CBP31-BC interact with any IgG molecules based on different binding affinities [34] , the CBP31-BC-based LFIA is generally suitable for application to samples that do not contain antibodies. However, SARS-CoV-2-specific IgG and IgA appear in nasopharyngeal samples within 2–8 weeks after symptom onset, but not before one week after symptom onset [35] , [36] . Considering that a diagnosis is made early after the appearance of symptoms, we speculated that the developed LFIA could detect SARS-CoV-2 in nasopharyngeal samples without competition between the capture antibody used and other human antibodies on the BC domains.…”