The recent SARS epidemic has boosted interest in the discovery of novel human and animal coronaviruses.By January 2008,more than 3000 coronavirus sequence records,including more than 250 complete genomes,are available.The number of coronavirus species with complete genomes available has increased from nine in 2003 to 25 in 2008,of which six,including human coronavirus HKU1,bat SARS coronavirus,group 1 bat coronavirus HKU2,groups 2c and 2d coronaviruses,were sequenced by our laboratory.Recently,we have also developed a comprehensive database,CoVDB (http://covdb.microbiology.hku.hk),of annotated coronavirus genes and genomes,for rapid and accurate batch sequence retrieval,the cornerstone and bottleneck for comparative gene or genome analysis.With the increasing amount of genomes available and the user-friendly database,easy comparative genome analysis,that will facilitate the discovery of potential novel drug targets for this emerging group of viruses,can be performed.