Coronavirus in severe acute respiratory syndrome (SARS).

In November 2002, an outbreak of a life-threatening ‘atypical pneumonia’ for which no etiological agent could be identified occurred in Guangdong Province, China. In March 2003, a similar outbreak was reported in Hong Kong [1]. Cases of similar respiratory illness were subsequently reported globally including China, Taiwan, Singapore, Vietnam, Canada and USA. This syndrome is a new clinical entity and has been designated ‘severe acute respiratory syndrome’ (SARS). Up to the time of writing, the World Health Organization had reported .6200 cases and 435 deaths in 30 countries as a result of SARS (see http://www.who.int/csr/sarscountry/2003_05_03/en). Vigorous research has been carried out worldwide to understand the cause and the possible preventive measures for this disease, which was believed to be caused by a highly contagious virus. In less than four weeks after the global outbreak, a novel coronavirus [SARS-coronavirus (SARS-CoV)] was identified in the blood, respiratory specimens (oropharyngeal wash, nasopharyngeal aspirate, sputum and lung biopsy) and stools of SARS patients by various research groups [2–4]. Typical coronavirus particles of 80–140 nm in diameter, with 20–40 nm complex surface projections surrounding the periphery, were seen under electron microscopy [2]. Direct cytopathic effects could be demonstrated on inoculating the viral isolates into African Green Monkey Kidney (Vero E6) cells, indicating pathogenic properties of this novel coronavirus [2,4]. Comparing the nucleotide sequences at limited regions of the SARS-CoV genome has found ,40–50% difference from that of other human and animal coronaviruses [2,3]. Recently, the sequencing of the entire genome of many SARS-CoV strains has been completed [5]. It is a single-stranded, plus-sense RNA virus, ,30 kb in length, with a genomic sequence that does not closely resemble any of the previously characterized coronaviruses [6,7]. All these data support an etiological role of this novel coronavirus in the pathogenesis of SARS.