Protection against influenza B virus infection by immunization with DNA vaccines

protection against a lethal influenza B virus infection was examined in BAL B/c mice immunized with plasmid DNAs encoding hemagglutinin (HA), neuramini dase (NA and NE) and nucleoprotein (NP) from the B/Ibaraki/2/85 virus. Each DNA vaccine was administered twice, 3 weeks apart, at a dose of 1 mug per mouse by particle-mediated DNA transfer to the epidermis (gene gun) or at a dose of 30 mug per mouse by electroporation into the muscle. Three weeks a fter the second vaccination, the mice were challenged with a lethal dose of homologous virus. HA and NA DNAs conferred complete protection against the lethal viral challenge, whereas NE and NP DNAs failed to provide protectio n against infection. Furthermore, protection in different strains of mice, BALB/c, B10 and C3H. immunized with HA and NA DNAs was compared. Both HA an d NA DNAs conferred complete protection against the lethal challenge in all the tested mouse strains. These results suggest that both the HA and NA mo lecules can be used as vaccine components to provide effective protection a gainst influenza B virus infection. (C) 2001 Elsevier Science Ltd. All righ ts reserved.