Protection and antibody responses in different strains of mouse immunized with plasmid DNAs encoding influenza virus haemagglutinin, neuraminidase and nucleoprotein

Protection against influenza virus infection and antibody responses in mice vaccinated with plasmid DNAs encoding haemagglutinin (HA), neuraminidase ( NA) and nucleoprotein (NP) were compared among BALB/c (H-2(d)), B10 (H-2(b) ) and C3H (H-2(k)) mice. Mice were inoculated with each DNA construct twice , 3 weeks apart, at a dose of 1 mu g per mouse by particle-mediated DNA tra nsfer (gene gun) to the epidermis. They were challenged with a lethal dose of the homologous virus 7 days after the second vaccination, NA-DNA provide d significant protection in all strains of mouse, whereas HA-DNA afforded s ignificant protection only in BALB/c mice. The serum antibody titres agains t NA or HA molecules in BALB/c, C3H and B10 mice were high, intermediate an d low, respectively. NP-DNA failed to provide protection in any strain of m ouse, and elicited low titres of anti-NP antibodies, These results suggest that NA-DNA can be used as a vaccine component to provide effective protect ion against influenza virus infection in various strains of mouse.