Luis Enjuanes of the Autonomous University of Madrid and colleagues announced the development of the first working vaccine for Middle East respiratory syndrome coronavirus (MERS-CoV) in the Sept. 10, 2013, edition of the journal mBio®.
The urgency for development of a vaccine is evinced by the 50 percent death rate in people who have acquired the disease even though only 108 known cases have been described. The disease could mutate into a much more easily transferable form that could hasten the already growing number of cases of MERS-CoV outside the Middle East. There is a viable antiviral therapy for MERS-CoV but the death rate from the disease is still 50 percent even with antiviral therapies.
Enjuanes cloned MERS-CoV and added mutations in the most likely genes that would produce a vaccine. The researchers found several sites in the MERS-CoV genes that prevent the virus from reproducing but this path would not lead to a vaccine. A vaccine needs a virus that can replicate itself so sufficient supplies of the vaccine altered virus can be produced in animal hosts.
The scientists discovered that alteration of the envelope protein of the MERS-CoV cell produced a virus that is not protected from the antigen producing activity that occurs during infection. Once the antigens to MERS-CoV have been created the virus from the vaccine dies.
The new vaccine for MERS-CoV is now in clinical trials.