Antigenic Cross-Reactivity between the Nucleocapsid Protein of Severe Acute Respiratory Syndrome (SARS) Coronavirus and Polyclonal Antisera of Antigenic Group I Animal Coronaviruses: Implication for SARS Diagnosis

Severe acute respiratory syndrome (SARS) is an emerging infectious disease of significant public health concern (3). The causative agent of SARS was shown to be a previously unrecognized virus within the family Coronaviridae, designated SARS-associated coronavirus (SARS-CoV) (1, 4, 7). There exist three known antigenic groups (I, II, and III) of animal coronaviruses, causing important and severe respiratory and enteric diseases in livestock, poultry, and laboratory animals and common colds (strains 229E and OC43) in humans (3). Sequence analyses revealed that SARS-CoV is not a derivative of any known animal coronaviruses (5, 8). Nevertheless, Ksiazek et al. (4) showed that polyclonal antibodies from antigenic group I coronaviruses, including human coronavirus 229E, feline infectious peritonitis virus (FIPV), and porcine transmissible gastroenteritis virus (TGEV), reacted with SARS-CoV-infected Vero cells.