Researchers in Germany have found a new way to make a flu vaccine. Their approach, shown to protect mice against the virus, utilizes messenger RNA instead of purified protein to generate the immune response. If it proves effective in humans it could decrease the cost of making vaccines, and cut production time by two-thirds.
Culturing the viruses in this way is costly and labor-intensive. Generating the large amounts of viruses used for vaccines each year takes a good six months. And results will vary, owing to the fact that different viruses will grow better or worse in the culture preparations.
Scientists at the Friedrich-Loeffler-Institute and biotech company CureVac have taken advantage of the body’s own machinery in an attempt to shortcut the vaccine production process. Rather than growing up viruses and purifying their proteins, their ‘vaccines’ contain pieces of synthetic messenger RNA (mRNA) which encoded the viral surface proteins, in this case from the H1N1 strain. mRNA is the single-stranded molecule which carries the copy of a protein sequence found in DNA. It’s shuttled outside the cell’s nucleus to the cytoplasm where it is read and directs the binding of amino acids into a protein. Injecting the mRNA beneath the skin of mice caused the animals’ own cells to generate the viral proteins. After being given just two injections adult mice were protected from illness due to influenza for the rest of their lives. The injections, however, still offered protection but weren’t as effective when given to very young or “elderly” mice.
The vaccine was also tested on pigs and ferrets. The immunity of these animals wasn’t assessed directly by challenging them with influenza but, up to 8 weeks after injection, their blood sera showed antibodies and other indicators of immunity against the flu virus. The immune response from both animals was in fact sufficient to meet the requirements set by the European Medicines Agency for vaccine development.