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Adaptive Evolution of MERS-CoV to Infect Different Species

Colorized scanning electron micrograph of Middle Eastern Respiratory Syndrome virus particles (yellow) attached to the surface of an infected VERO E6 cell (blue). Image captured and color-enhanced at the NIAID Integrated Research Facility in Fort Detrick, Maryland. Credit: NIAID

New research published in Cell Reports from scientists at the National Institute of Allergy and Infectious Diseases (NIAID) shows how Middle East respiratory syndrome coronavirus (MERS-CoV) can adapt to infect cells of a new species, which suggests that other coronaviruses might be able to do the same.

First identified in 2012, MERS-CoV consistently jumps from dromedary camels to people, resulting in periodic outbreaks with a roughly 35 percent fatality rate.

Evidence suggests that both MERS-CoV and severe acute respiratory syndrome coronavirus (SARS-CoV) originated in bats before transmitting to camels and civets, respectively. While many other coronaviruses in nature are not known to infect people, MERS-CoV and SARS-CoV are notable for their ability to infect a variety of different species, including humans.

Desmodus rotundus bat - Research on MERS-CoV species adaptation
This illustration shows the bat species used in the study, Desmodus rotundus, or vampire bat, and representations of MERS-CoV (purple) interacting with host receptor DPP4 (gold). Credit: NIAID

To evaluate how MERS-CoV evolves to infect host cells, the scientists tested 16 bat species and found that the virus could not efficiently enter cells with receptors from the common vampire bat, Desmodus rotundus. They then grew virus on cells that had vampire bat receptors and observed the virus evolving to better infect the cells. After a few generations, the virus had completely adapted to the vampire bat receptor.

By studying how the shape of MERS-CoV changed over time to attach to the new host receptor, the scientists found similarities with prior studies of SARS-CoV. Thus, while these two viruses are different, they use the same general approach to enter the cells of new species.

Understanding how viruses evolve to infect new species will help researchers determine what is required for viruses to emerge and spread in new hosts. These findings also may be important for developing new vaccines, which viruses often evolve to avoid.

Read the study: M Letko et al. Adaptive evolution of MERS-CoV to species variation in DPP4.

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