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Engineered MERS strain may be vaccine candidate
An engineered strain of the Middle East respiratory syndrome, or MERS, coronavirus could be used to develop a vaccine for the disease, according to data published in mBio.
The synthetic virus has a mutation in its envelope protein that allows it to infect a cell and replicate itself but does not spread to other tissue and cause disease.
As of Sept. 20, there have been 130 laboratory-confirmed cases of MERS coronavirus and 58 deaths, according to WHO.
“Our achievement was a combination of synthetic biology and genetic engineering,” Luis Enjuanes, PhD, of the Autonomous University of Madrid, said in a press release. “The injected vaccine will only replicate in a reduced number of cells and produce enough antigen to immunize the host.”
Enjuanes and colleagues created the clone of the MERS coronavirus genome based on published data of its gene sequence. They inserted the chromosome into a bacterial artificial chromosome and mutated its genes to evaluate the virus’s ability to infect, replicate and reinfect human cells.
They found that mutations that disabled the accessory genes 3, 4a, 4b and 5 did not have a significant effect on the virus. However, mutations in the envelope protein allowed the virus to replicate its genetic material but not to infect nearby cells. A virus that cannot propagate itself would be unable to grow without help, which the researchers did by providing it with a supplemental envelope protein.
“To grow the virus, we created packaging cells that express the envelope protein missing in the virus,” Enjuanes said. “In these cells, and only within them, the virus will grow by borrowing the envelope protein produced by the cell. When the virus is administered to a person for vaccination, the person will not be able to provide the envelope protein to the defective virus, causing the virus to die off after producing antigens to fight a MERS coronavirus infection.”
Disclosure: The researchers report no relevant financial disclosures.