LIPS method for the detection of SARS‐CoV‐2 antibodies to spike and nucleocapsid proteins

Haljasmägi, Liis; Remm, Anu; Rumm, Anna Pauliina; Krassohhina, Ekaterina; Sein, Hanna; Tamm, Anu; Kisand, Kai; Peterson, Pärt

Profiling antibodies to SARS‐CoV‐2 can help to assess potential immune response after COVID‐19 disease. Luciferase IP system (LIPS) assay is a sensitive method for quantitative detection of antibodies to antigens in their native conformation. We here describe LIPS to detect antibody responses to SARS‐CoV‐2 spike (S) and nucleocapsid (N) proteins in COVID‐19 patients. The antibodies targeted both S and N fragments and gave a high assay sensitivity by identifying 26 out of 26 COVID‐19 patients with N antigen or with three protein fragments when combined into a single reaction. The assay correlated well with ELISA method and was specific to COVID‐19 as we saw no reactivity among uninfected healthy controls. Our results show that LIPS is a rapid and measurable method to screen antibody responses against SARS‐CoV‐2 antigens.