Friday, October 11, 2013

Scientists Confirm MERS Originated in Bats

Researchers have shown the MERS virus originated in bats.
Scientists have shown that the deadly Middle East Respiratory Syndrome (MERS) virus originated in bats before it adapted to spread to humans. They have identified three receptors which show the virus has been circulating in the bat population for some time and several adaptations were evolved to combat it. According to this report from Virology Journal:
"Cell-surface receptors such as DPP4 play a key role in facilitating viral invasion and tropism. As a consequence, the long-term co-evolutionary dynamics between hosts and viruses often leave evolutionary footprints in both receptor-encoding genes of hosts and the receptorbinding domains (RBDs) of viruses in the form of positively selected amino acid residues (i.e. adaptive evolution)... 
These residues therefore provide direct evidence of a long-term co-evolutionary history between viruses and their hosts. We also observed several variable regions within the bat RBD, that may also have resulted from virally-induced selection pressure and which merit additional investigation in a larger data set."
This is one more piece to the puzzle regarding the origins of this mysterious disease. The report did not shed any light on how the disease is being transmitted to humans as most victims have had no contact with bats.  Researchers suspect an 'unknown reservoir' of the virus exists in Saudi Arabia, perhaps in an intermediary animal host, which has repeatedly infected humans and has resulted in three genetically distinct versions of the virus in humans.

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