A team of researchers at Georgia State University have developed a universal flu vaccine that protects against several influenza A virus subtypes.
In a study published in the journal npj Vaccines, the team outlined the effectiveness of the newly developed universal flu vaccine. The researchers tested the vaccine in mice exposed to several subtypes of influenza A viruses. According to the results, the vaccine not only stimulated an immune response in the mice but also led to viral clearance from the lungs.
Influenza, also known as flu, is a common respiratory infection, and results from various influenza viruses. These include type A, type, B, and type C. Influenza A and B viruses are responsible for causing annual flu epidemics, with type A being the most common. Moreover, type A virus is typically divided further into subtypes based on the surface proteins haemagglutinin (H) and neuraminidase (N). Although several subtypes circulate in the environment, H1N1 and H3N2 are the most common.
Protection Across Subtypes
However, influenza viruses constantly mutate to form more virulent variants. Hence, seasonal flu vaccines are updated every year to include those strains circulating in the environment. They typically include one influenza A(H1N1) virus, one influenza A(H3N2) virus, one influenza B/Victoria lineage virus, and one influenza B/Yamagata lineage virus.
Compared to H1N1, circulating strains of H3N2 viruses have stalk mutations. It is difficult to develop effective H3 stalk-based vaccines. As a result, vaccine effectiveness against the H3N2 virus has greatly decreased over the years.
The researchers developed the new vaccine by genetically linking the stalk protein in the H3N2 viruses with the virus’s extracellular domain of matrix 2 (M2e).
When tested against various subtypes such as H1N1, H5N1, H9N2, H7N9, and H3N2, the M2e-stalk protein evoked an immune response. This was evident in both adult and aged mice.
However, this is not the first time researchers have worked on a universal flu vaccine. Last year, the National Institutes of Health announced the testing of a vaccine FluMos-v1 in humans.
Jeeva Subbiah et al, A chimeric thermostable M2e and H3 stalk-based universal influenza A virus vaccine, npj Vaccines (2022). DOI: 10.1038/s41541-022-00498-6