The severe acute respiratory syndrome (SARS) has recently been identified as a new
clinical entity. SARS is thought to be caused by an unknown infectious agent.
Clinical specimens from patients with SARS were searched for unknown viruses with
the use of cell cultures and molecular techniques.
A novel coronavirus was identified in patients with SARS. The virus was isolated in
cell culture, and a sequence 300 nucleotides in length was obtained by a polymerase-chain-reaction
(PCR)-based random-amplification procedure. Genetic characterization indicated that
the virus is only distantly related to known coronaviruses (identical in 50 to 60
percent of the nucleotide sequence). On the basis of the obtained sequence, conventional
and real-time PCR assays for specific and sensitive detection of the novel virus were
established. Virus was detected in a variety of clinical specimens from patients with
SARS but not in controls. High concentrations of viral RNA of up to 100 million molecules
per milliliter were found in sputum. Viral RNA was also detected at extremely low
concentrations in plasma during the acute phase and in feces during the late convalescent
phase. Infected patients showed seroconversion on the Vero cells in which the virus
The novel coronavirus might have a role in causing SARS.
Copyright 2003 Massachusetts Medical Society