Emergencies preparedness, response

Summary on major findings in relation to coronavirus by members of the WHO multi-centre collaborative network on SARS aetiology and diagnosis

4 April 2003

Since its inception on 17 March network members obtained the following results:

  • A new coronavirus which is unlike any other known members of the genus Coronavirus has been isolated consistently by several network laboratories from SARS patients from several countries.
  • This virus causes a cytopathogenic effect (CPE) in VERO cells and FRhk-4 cells, which can be inhibited with serum from SARS convalescent patients.
  • Electron microscopic pictures from cell-culture and respiratory specimens from SARS patients show coronavirus-like particles.
  • Immunofluorescence assays (IFA) with serum from convalescent patients detect cells infected with the virus in cell-culture.
  • Reactivity with a new coronavirus could not be detected in serum from several hundreds of non-SARS individuals in the U.S.A., Canada and Hong Kong.
  • Generic coronavirus primers detect a new coronavirus RNA in cell-culture and in specimens from SARS patients. Specific primers have been developed in several laboratories and are currently been compared for sensitivity (PCR primers for SARS developed by WHO Network Laboratories).
  • Hyperimmune sera against Transmissible Gastroenteritis Virus (TGEV), Feline Infectious Peritonitis virus (FIPV), Murine Hepatitis Virus (MHV) and 229E human coronavirus inhibit growth of a new coronavirus in cell-culture.
  • Partial sequencing of a new coronavirus in several laboratories confirms affiliation of a new coronavirus to the genus Coronavirus as well as dissimilarities with known members belonging to each of the three existing groups of this genus.
  • Animal inoculation experiments are ongoing.

It is currently agreed that this coronavirus is the major causative agent of SARS. Human metapneumovirus (hMPV) has also been found in respiratory specimens and antibodies against hMPV in serum of some SARS patients, as well as evidence of dual infection with hMPV and the new coronavirus . The significance of hMPV in SARS remains unclear at this time and will be reported on later.