MERS transmission link between bats and humans revealed
Key to understanding how MERS spreads is understanding what prompted MERS to jump from bats to humans. To answer this, scientists needed to find a virus that was isolated in bats but had the potential to move into a human model. For this they isolated a virus termed HKU4. This virus is related to MERS but has, so far, infected bats but not humans. Thus the virus serves as a good model for understanding the bat-to-human transmission process of MERS and related viruses.
After investigating both MERS and HKU4, researchers observed two major indicators explaining how MERS had adapted to human cells in a way HKU4 had not done yet.
The first discovery was that HKU4 virus recognizes the same receptor, DPP4, as MERS virus. However, MERS virus uses the DPP4 molecule from human origin better, whereas HKU4 virus uses the DPP4 molecule from bat origin better. HKU4 also struggles to enter human cells once attached to the DPP4 receptor on the human cell surface. MERS does not have such a problem, though both viruses are able to enter bat cells.
From this the researchers concluded that the MERS virus has successfully adapted to human cells for efficient infections, and HKU4 virus can potentially infect human cells. MERS and MERS-related bat viruses present a constant and long-term threat to human health.
Further study is required to learn how bat viruses infect cells and can jump species. From this scientists, might one day be able to develop strategies to block the transmission of such viruses to humans.
The research was led by Fang Li, Ph.D., associate professor of Pharmacology at the University of Minnesota Medical School. The findings have been published in the most recent edition of the Proceedings of the National Academy of Sciences. The paper is titled “Receptor usage and cell entry of bat coronavirus HKU4 provide insight into bat-to-human transmission of MERS coronavirus.”