A novel human coronavirus, hCoV-EMC, has recently emerged in the Middle East region. The virus has caused severe acute respiratory infection (SARI) in at least nine patients to date. Latest reports from the World Health Organization (WHO) suggest that infections have occurred since April 2012, as hCoV-EMC was found retrospectively in two patients from a group of 11 epidemiologically linked cases of SARI in Jordan, eight of whom were healthcare workers.

The pathogen of hCoV-EMC is closely related to SARS (New SARS-like Virus), and it may also be able to infect pigs and a wide range of bat species. The virus has been fully sequenced and its genome revealed that it is closely related to the SARS coronavirus. The SARS virus uses a receptor called ACE2 to open cells, which are found deep inside the human lung. If hCoV-EMC used the same receptor, researchers would be able to understand how the virus spreads and how to stop it.

hCoV-EMC receptor, by which the novel coronavirus infects human, is studied. Researchers engineered baby hamster kidney cells to express the human ACE2 receptor. The cells could be infected with the SARS coronavirus, but not hCoV-EMC. This led the scientists to conclude that hCoV-EMC doesn't use ACE2 to get into cells. It's yet unclear which receptor hCoV-EMC uses. (Fig. 1)

Epidemiologists also wanted to know which species of animals hCoV-EMC was capable of infecting to keep it from spreading further, so they tested cells from humans, pigs and bats, the key natural reservoirs of coronaviruses. They found that hCoV-EMC could infect all of these cells. Most coronaviruses come from bats, but once they jump to other species, they usually can never reinfect bat cells. This could mean that hCoV-EMC is unique in its ability and researchers believe it could still have come from a bat. Either way, they believe the new coronavirus can infect a wide range of species, so public health officials may have to start looking for infections and deaths in local wild animal and livestock populations.

Receptor studies of hCoV-EMC

Fig. 1 The hCoV-EMC virus could still enter bat cells (blue) even when the ACE2 receptor was blocked by antibodies (red). Studies in monkey kidney cells (bottom) also showed that blocking ACE2 prevented the entry of the SARS virus (left) but not hCoV-EMC (right).
Credit: Marcel A. Müller and Christian Drosten/University of Bonn Medical Center, Germany

References

  1. van Boheemen S, et al. (2012) Genomic characterization of a newly discovered coronavirus associated with acute respiratory distress syndrome in humans. mBio. 3(6):e00473-12.
  2. Kindler E, et al. (2013) Efficient replication of the novel human betacoronavirus EMC on primary human epithelium highlights its zoonotic potential. mBio. 4(1):e00611-12.
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