Immunization with plant-expressed hemagglutinin protects chickens from lethal highly pathogenic avian influenza virus H5N1 challenge infection
Highly pathogenic avian influenza (HPAI) is a striking disease in susceptible poultry, which leads to severe economical losses. Inactivated vaccines are the most widely used vaccines in avian influenza virus (AIV) vaccination programs. However, these vaccines interfere with serological detection of wild type AIV infections in immunized populations. Using vaccines that allow differentiation between infected and vaccinated animals (DIVA strategy) would stop current stamping out policy. Therefore, novel vaccination strategies are needed to allow improved protection of animals and humans from HPAIV infection. The presented study analysed for the first time the immunogenic capacity of plant-expressed full-length hemagglutinin (rHA0) of HPAIV H5N1 in several vaccine formulations within the highly relevant host species, chicken. We were able to express plant-expressed rHA0 at high levels and could show that, when administered with potent adjuvants, it is highly immunogenic and can fully protect chicken against lethal challenge infection. Real-time RT-PCR and serological tests demonstrated only marginally increased virus replication in animals vaccinated with plant-derived rHA0 compared to animals immunized with an inactivated reference vaccine. In addition, use of plant-expressed rHA0 also allowed an easy serological differentiation of vaccinated from AIV-infected animals based on antibodies against influenza virus NP protein.
Hoffmann, Donata / Giritch, A. / Geisler, K. / et al: Immunization with plant-expressed hemagglutinin protects chickens from lethal highly pathogenic avian influenza virus H5N1 challenge infection. 2010.
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