DNA vaccination against respiratory influenza virus infection

DNA vaccination using plasmid encoding the hemagglutinin (HA) gene of influenza A/PR, 8/34 virus to induct long-lasting protective immunity against respiratory infection was evaluated in this study. Using liposomes as carriers, the efficacy of DNA vaccines was determined using a lethal influenza infection model in mice. Mice immunized intranasally or intramuscularly with liposome-encapsulated pCl plasmid encoding HA (pCl-HA10) were completely protected against an intranasal 5 LD50 influenza virus challenge. Mice immunized with liposome-encapsulated pCl-HA10, but not naked pCl-HA10, by intranasal administration were found to product high titers of serum IEA. These results suggest DNA vaccines encapsulated in liposomes are efficacious in inducing complete protective immunity against respiratory influenza virus infection. Crown Copyright (C) 2001 Elsevier Science Ltd. All rights reserved.