Vaccine effectiveness against H3N2 was low during the past decade, only about 33 percent, and dropped to 6 percent during the 2014-2015 flu season. New mutations of H3N2 variants emerged with increased virulence. Also, the outbreak of H7N9, another influenza A subtype, caused concern for potential pandemics. Therefore, developing an effective vaccine to protect against these viruses is a high priority.
“The M2e-stalk protein, for the first time, could be easily produced in bacterial cell cultures at high yields and was found to confer protection against heterologous and heterosubtypic cross-group subtype viruses (H1N1, H5N1, H9N2, H3N2 and H7N9) at similar levels in adult and aged mice,” said Dr. Sang-Moo Kang, senior author of the study and a professor in the Institute for Biomedical Sciences at Georgia State. “These results provide evidence that M2e-stalk genetic fusion proteins can be produced in a large scale at low cost and developed as a universal influenza A virus vaccine candidate for young and aged populations.”
The study found this novel M2e-stalk protein vaccine induced M2e and stalk-specific Immunoglobulin G (IgG) antibodies that recognized antigenically diverse influenza viral antigens on virus particles and on the infected cell surface. In addition, the vaccine stimulated protective cellular T cell immunity and effective lung influenza viral clearance in mice.