DNA expressing whole or parts of a spike-like protein used by MERS coronaviruses to penetrate host cells during infection can elicit a balanced production of type I and type II helper T cells, as well as high levels of immunoglobin antibodies, in mice. The study, conducted by researchers from King Fahd Medical Research Centre in collaboration with a KACST researcher and international colleagues, might lead to safer and more effective vaccines for controlling and preventing MERS outbreaks.
Viruses not only have the capacity to cause disease and death, but can also change genetic makeup. By doing so, they spread more quickly and efficiently, whether from animals to humans or from humans to humans. MERS, for example, is a coronavirus that originated in bats but was later transmitted to camels and humans. The pathogen, which causes severe respiratory problems, first emerged in Saudi Arabia in 2012. In just six years, the coronavirus has infected 1,800 people and resulted in more than 600 deaths in 25 countries.
A way to control and prevent MERS outbreaks is to vaccinate people in high-risk groups: for example, children, the elderly and pregnant women. DNA vaccines are ideal because they can be produced on a large scale with ease in a timely manner. They are also safer in humans than protein-based vaccines, which can carry foreign material that might be rejected by a person’s immune system.
Most importantly, DNA vaccines can elicit the production of helper T cells and antibodies — the ‘commanders’ and ‘weapons’ needed for battling against MERS viruses in the war of immunity.
The research team found that immunity set up by their DNA vaccine in mice was effective against multiple strains of MERS coronavirus, including those of human and camel origin. Previously, scientists experimented with protein-based vaccines containing whole or parts of the spike protein to stimulate an immune response in animals. However, past experiences with the development of SARS vaccines for the 2003 epidemic in Hong Kong have raised concerns over their safety and efficacy.
Taken together, DNA vaccines might have advantages over protein-based vaccines that warrant further investigation and testing.
Sanki, M. A., Al-Muhanna, M. K., Alhabbab, R. Y., Azhar, E. I., Li, X. & Hashem, A. M. Immunogenicity of candidate MERS-CoV DNA vaccines based on the spike protein. Scientific Reports 7, 44875 (2017). | article