Abstract: The disclosure relates to the technical field of virus detection, in particular, to an IgA antibody and a kit capable of specifically recognizing RBD protein. The antibody can be used as a calibrator of IgA antibody against the RBD protein of SARS-CoV-2.

Abstract: Disclosed are a recombinant RBD protein of SARS-CoV-2, and a method for preparing the same. The recombinant RBD protein has a signal polypeptide sequence, an RBD protein sequence, a transmembrane domain sequence and a tag sequence in order from N-terminus to C-terminus. The recombinant RBD protein may be expressed on cell membranes, which facilitates protein stability, enrichment and detection.

Abstract: Provided are a recombinant N protein of SARS-CoV-2 and methods for preparing the same and for purifying the same. The recombinant N protein of SARS-CoV-2 has an N protein sequence, wherein each of both ends of the N protein sequence are linked to an oligolysine fragment. An expression method for the recombinant N protein includes: a. providing a sample including the recombinant N protein; and b. performing cation exchange chromatography resin purification treatment at least once, and collecting breakthrough substance. The method may effectively improve the expression purity of the recombinant N protein.