Coronavirus nucleocapsid protein

The nucleocapsid (N) protein is a protein that packages the positive-sense RNA genome of coronaviruses to form ribonucleoprotein structures enclosed within the viral capsid. In addition to its interactions with RNA, N forms protein-protein interactions with the coronavirus membrane protein (M) during the process of viral assembly. N also has additional functions in manipulating the cell cycle of the host cell. The N protein is highly immunogenic, with antibodies to the N protein found in the majority of patients recovered from SARS and COVID-19. In COVID-19 specifically, the rate at which patients develop anti-N antibodies is estimated at 80%. This proportion varies depending on the measurement methodology utilized and typically increases in correlation with disease severity.