The Emergence of Human Coronavirus EMC: How Scared Should We Be?

Chan, Renee W. Y.; Poon, Leo L. M.

In terms of cellular tropism, Kindler et al. are the first to show the cellular preference of HCoV-EMC for human non-ciliated bronchial epithelial cells. So far, susceptibilities of the human pseudostratified bronchial epithelial culture to coronaviruses causing the common cold (e.g., HCoV-229E, HCoV-OC43, HCoV-NL63) (6) and to SARS-CoV are comparable to that observed after HCoV-EMC infection. Interestingly, these human coronaviruses seem to have different cell specificities; non-ciliated cells are infected by HCoV-229E and HCoV-EMC, while ciliated cells are more prone to infections by HCoV-OC43, HCoV-NL63, and SARS-CoV. Nevertheless, this finding alone is not sufficient to explain their differential pathogenicities in humans. As acute pneumonia is one of the key presentations in HCoV-EMC infection in humans, the characterization of HCoV-EMC in tissues from lower respiratory tracts such as alveolar epithelial cells or alveolar macrophages might provide a more comprehensive picture of this novel disease.