DNA vaccination against respiratory influenza virus infection

DNA vaccination using plasmid encoding the hemagglutinin (HA) gene of influ enza A/PR, 8/34 virus to induct long-lasting protective immunity against re spiratory infection was evaluated in this study. Using liposomes as carrier s, the efficacy of DNA vaccines was determined using a lethal influenza inf ection model in mice. Mice immunized intranasally or intramuscularly with l iposome-encapsulated pCl plasmid encoding HA (pCl-HA10) were completely pro tected against an intranasal 5 LD50 influenza virus challenge. Mice immuniz ed with liposome-encapsulated pCl-HA10, but not naked pCl-HA10, by intranas al administration were found to product high titers of serum IEA. These res ults suggest DNA vaccines encapsulated in liposomes are efficacious in indu cing complete protective immunity against respiratory influenza virus infec tion. Crown Copyright (C) 2001 Elsevier Science Ltd. All rights reserved.