Influenza A is responsible for flu epidemics worldwide. This virus changes constantly making effective vaccine design very challenging. Currently, vaccines must be redesigned to account for the changes in the virus strains. However, there are influenza viral peptides that are conserved across different strains. These peptides may serve as the basis for the development of vaccines effective against different strains.
Researchers conducted studies to determine the immunogenic potential of peptides (Matrix 1 or M1) containing various T-cell epitopes (parts of antigens recognized by the immune system). Unlike influenza A surface proteins, the M1 peptide has a low rate of mutation. They tested three highly conserved M1 peptides for their potential to elicit an immune response without toxic or allergenic effects. They tested the allergenic and toxic potential using an online prediction tool (AlgPred). A given molecule is considered to be an allergen if there is at least 35% identity with or has six adjoining amino acids corresponding to a known allergen.
Immunogenic potential was assessed by incubating one of each of the three M1 peptides with peripheral blood mononuclear cells collected from healthy volunteers. Since cytokines are secreted with the initiation of a T-cell related immune response, measurement of interferon-gamma was measured using an antibody-based approach (ELISA) after stimulation of peripheral blood mononuclear cells by M1 peptide. The researchers also used a dye-based laboratory test to determine the lymphocyte proliferation. A dye, MTT was added and incubated with the cells and M1 peptides. MTT is acted upon by active cells, and a blue color is formed. The level of this coloration is measured to indirectly determine the level of living cells present.
Neither of the peptides tested showed allergenic or toxic potential. However, each of the peptides, albeit to different extents, induced the release of interferon-gamma from the peripheral blood mononuclear cells. Lymphocyte proliferation was also stimulated by each of the M1 peptides. These results suggest that the studied conserved peptides, which contain various T-cell epitopes, can stimulate immune responses. This information has the potential to form the basis for the development of a vaccine effective against various strains of influenza A.
Lohia, N., & Baranwal, M. (2017). Immune response of highly conserved influenza A virus matrix 1 peptides. Microbiology And Immunology. doi:10.1111/1348-0421.12485