Used in diagnostic assays to detect the presence of viral nucleocapsid proteins, particularly in respiratory viruses like SARS-CoV-2. Enables early detection through immunoassays such as ELISA, lateral flow tests, and immunofluorescence. Plays a key role in research settings for studying viral replication and immune response. Also utilized in developing rapid antigen tests for point-of-care testing due to its high specificity for the nucleocapsid antigen.