Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2000
Publication Date: 12/15/2000
Interpretive Summary: The importance of influenza viruses as worldwide pathogens in humans, domestic animals, and poultry is well recognized. Currently, influenza vaccines are not widely used in the poultry industry. Development of an influenza vaccine that could be administered in ovo would have important practical implications in poultry. The Venezuelan equine encephalitis virus replicon (VRP) system is a newly developed a very useful vaccine. Previous studies showed that mice vaccinated with a VRP containing the hemagglutinin gene of influenza were protected from lethal challenge. In these studies, we examined the usefulness of VRPs in chickens. We found that chickens vaccinated at 1 and 14-days of age were completely protected from lethal infection. Surprisingly, in ovo inoculation offered partial protection. These studies suggest that the Venezuelan equine encephalitis virus replicon (VRP) system may be a very promising vaccine approach for poultry.
Technical Abstract: Venezuelan equine encephalitis virus replicon particles (VRP) containing the gene expressing hemagglutinin (HA) from the human Hong Kong influenza A isolate (A/HK/156/97) were evaluated as vaccines in chicken embryos and young chicks. Expressed HA was readily detected in bird-tissue staining with anti-H5 antibody and in chicken cells infected with the replicon preparations following immunoprecipitation with monoclonal antibody. Birds challenged with a dose of the lethal parent virus were protected to different extents depending on the age of the bird. In ovo and 1-day-old inoculated animals that received no boost with the VRP were partially protected; birds 2 weeks of age were completely protected with a single dose of VRP.