Protection of Mice with DNA Vaccines Encoding Influenza Virus Matrix Protein

Matrix protein (M) of influenza virus has been shown to have significant effect on virus replication and virulence. M1 gene and the extracellular part of M2 gene are highly conserved,which are the candidate sequences to construct DNA vaccines in providing across-protection against influenza A virus. Eukaryotic expression plasmids pCAGGSP7/M1 and pCAGGSP7/M2 were constructed to evaluate the protective abilities of the two genes in BALB/c mice. The mice were immunized with either plasmid DNA at most 6 times. Seven days after each immunization(starting from the 2nd immunization for M1 DNA or 4th for M2 DNA),a group of mice were challenged with a lethal dose of homologous influenza virus. The lung virus titers and survival rates of mice were detected. Results showed that,in mice immunized with M1 DNA,the protective ability were enhanced as injection time was added,while in mice immunized with M2 DNA,no protection was detected even after 6 times of injection. It indicated that only M1 DNA could afford partial protection in mice against lethal virus challenge.