The Search for a Universal Influenza Vaccine: Possibilities and Limitations

Relevance.Upon the unquestionable utility of regular season vaccination influenza vaccine effectiveness varies depending on how vaccinal strains to be in accord with seasonal circulating influenza strains, i.e. the influenza vaccines are virtually strain-spesific and not able to elicit broad, protective immune responses. Aim is widening the scope of bioinformatics applications to show the possibility to construct H1 and H3 hemagglutinin structures that contain long identical invariant (conservative) sequences from various strains and can accordingly be used as a universal influenza vaccine at the level of strain subtypes for the future seasons and also to discuss possibilities and limitations in the search for the universal influenza vaccine. Materials and methods. For the computer analysis, the database of the hemagglutinin (HA) primary structures of the H1N1 and H3N2 strains isolated in the influenza epidemiological season 2009/2010–2018/2019 were used from the Internet. For every epidemical season dominant and invariant H1 sequences (presenting the generalized HA images of circulating strains) are constructed and used for the comparison of seasons. The dominant sequence of the seasonal dominant sequences and the invariant sequences of the seasonal dominant sequences are used as the HA characteristics for ten year period. Results. The seasonal dominant HA sequences of the last ten year period contain a few changes, i.e. their structures are robust and each structure contains practically all identical conservative sequences of the HA of the following seasons. During the last ten years the bird and swine HA H1 and H3, in contrast to human HA H1 and H3, have requiredsignificant changes. Conclusion. The vacccines using the H1 and H3 dominant sequences for preceding epidemical seasons could be effective against the various strain subtypes in the future seasons