Viruses 2009, 1, 57-71; doi:10.3390/v1010057 viruses ISSN 1999-4915 www.mdpi.com/journal/viruses Review More and More Coronaviruses: Human Coronavirus HKU1 Patrick C. Y. Woo 1,2,3,†,*, Susanna K. P. Lau 1,2,3,†,*, Cyril C. Y. Yip 3, Yi Huang 3 and Kwok-Yung Yuen 1,2,3 1 State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China 2 Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China 3 Department of Microbiology, The University of Hong Kong, Hong Kong, China † These authors contributed equally to the manuscript * Authors to whom correspondence should be addressed; E-mails: