American scientists have developed an experimental universal influenza vaccine based on messenger ribonucleic acid (mRNA) molecules. In animal experiments, this vaccine can induce mice and ferrets to produce antibody responses to all 20 known influenza A and B strains, bringing new hope for the development of universal influenza vaccine. The relevant research was published in the latest issue of Science. Influenza viruses continue to evolve, so vaccine researchers need to develop vaccines against specific influenza strains that are expected to be prevalent in the current year every year, but they sometimes make wrong predictions, which means that the effect of vaccines will be compromised. Some researchers believe that a universal influenza vaccine that is effective for all influenza strains can be developed to replace the influenza vaccine developed every year. Scientists also try to achieve this goal by making vaccines containing common protein fragments of several influenza strains, but no universal influenza vaccine has been approved yet. In the latest study, a team at the University of Pennsylvania developed a vaccine based on mRNA molecules. Like DNA, mRNA contains the genetic code for making proteins. The newly developed influenza vaccine contains mRNA molecules encoding protein fragments contained in all 20 known influenza A and B virus strains. In the mouse experiment, the research team found that these animals produced specific antibodies against all 20 influenza virus strains, and these antibodies remained stable for up to 4 months. They also tested the vaccine on ferrets with similar results. In another experiment, the team gave mice a universal influenza vaccine and a dummy vaccine containing a non influenza protein. A month later, they infected the mice with two strains of H1N1 influenza virus (one strain contains H1 protein that is very similar to the protein in the vaccine, and the other is different). The results showed that among the vaccinated mice, all the mice exposed to the more similar H1 protein strain survived, 80% of the mice infected with the less similar H1 protein strain survived, and all the mice vaccinated with the false vaccine died about a week after infection. (Outlook New Times)