Immune Response in Mice Immunized with Chimeric H1 Antigens

Area of Science:

• Virology
• Immunology
• Vaccine Development

Background:

• Developing a universal influenza vaccine remains a significant global health challenge.
• Current vaccines target variable regions of the hemagglutinin (HA) protein, limiting broad protection.

Purpose of the Study:

• To investigate the potential of chimeric hemagglutinins (cHAs) based on conserved influenza HA sequences for a universal vaccine.
• To assess the immunogenicity and protective efficacy of H1 HA-based cHAs against influenza virus challenge.

Main Methods:

• Consensus sequence building was used to create two H1 HA-based chimeric hemagglutinins (cHAs) incorporating conserved sequences from H1, H5, and H9 HA subtypes.
• cHAs were expressed in *Drosophila* S2 cells and used to immunize mice.
• Immunized mice were challenged with an H1 virus, and sera were tested for haemagglutination inhibition (HI) activity against homologous and heterologous influenza strains.

Main Results:

• All mice immunized with H1 cHAs were protected from a lethal H1 virus challenge.
• Sera from mice immunized with H1 cHAs demonstrated cross-inhibitory activity against both the H1 challenge virus and an H5 virus isolate in HI assays.
• These findings indicate that cHAs elicit antibodies targeting conserved regions of the HA head and stalk.

Conclusions:

• Chimeric hemagglutinins (cHAs) derived from conserved influenza HA sequences can induce cross-reactive antibodies.
• H1 HA-based cHAs demonstrate significant potential as candidates for a universal influenza vaccine.
• Further development of cHAs may lead to a broadly protective vaccine against diverse influenza strains.