Novel 2-for-1 vaccine may help treat MERS

Scientists have created an innovative two-for-one vaccine that protects mice against both Middle East Respiratory Syndrome and rabies, paving the way for an effective human vaccine against the deadly MERS virus.
In a new study, researchers modified a rabies virus, so that it has a protein from the MERS virus.
Since it uses an already-tested vaccine for rabies, the innovative combination could speed development of a MERS vaccine for humans, researchers said.
Currently no vaccine exists for this new and highly fatal virus. The study found that the vaccine protected mice from infection with MERS.
"This is the first time anyone has used this strategy to create a MERS vaccine," said lead researcher Matthew B Frieman, associate professor at University of Maryland School of Medicine in the US.

"This could give us a powerful mechanism to fight the virus," said Frieman.

MERS has killed more than 630 people since it was first discovered four years ago in Saudi Arabia. It has infected more than 1,800, meaning that about a third of those who are infected die - a very high fatality rate for an infectious disease, researchers said.
It appears that the disease spreads to humans from camels, who may themselves have been infected by bats.
Through genetic engineering, Frieman and colleagues produced a modified rabies virus that expresses a protein from the surface of the MERS virus, known as a spike protein, on the surface of the rabies virus.

Scientists then treated the modified virus chemically, inactivating it so that it cannot replicate.
This inactivated virus is itself the vaccine, which triggers an immune response but poses no danger to the recipient, researchers said.
Since it included the MERS spike protein, the dual compound also triggered an immune response to MERS. In tests on mice, the MERS-rabies vaccine protected against both diseases.
The double vaccine could prove useful not only in humans, but in camels, which are the reservoir of the disease.
About 95 per cent of camels in the Middle East are infected with MERS when they are young; because their immune system reacts differently from humans', it gives them the sniffles rather than kills them, researchers said.

Frieman examined how the body responds to MERS. He examined a range of immune cells, to see which play the largest role in the body's response to the virus.
He examined three types of immune cell in particular: CD8 T cells, CD4 T cells, and macrophages. It appears that macrophages play a much larger role than the other two in protecting the body, at least in a mouse model of disease.
With this knowledge, researchers will now try to understand how macrophages accomplish this. By unravelling this, they could come up with better strategies to fight MERS.
The findings were published in the Journal of Virology.