Back to the past: do vector vaccines represent the future?
K.A. Schat Department of Microbiology and Immunology College of Veterinary Medicine, Cornell University Ithaca, NY 14853,
The intensive production of poultry meat and eggs depends to a significant degree on the use of vaccines. Until the development of recombinant DNA technology, these vaccines consisted of inactivated pathogens or attenuated live pathogens.
In general, the traditional, live vaccines have provided, and continue to provide, poultry with good to excellent protection. However, the use of live attenuated vaccines can have some negative consequences such as vaccine-induced mild reactions [e.g., Newcastle disease virus (NDV) vaccines] or even cause disease outbreaks [e.g., vaccinal laryngotracheitis after vaccination with chicken embryo origin vaccines for infectious laryngotracheitis (ILT)].
Another concern is the possible reversal to pathogenicity by mutations or recombination between field and vaccine strains.
The advance of recombinant DNA technology raised great expectations for the development of vaccines lacking these potential problems. USDA recognizes three categories of recombinant vaccines.
In this paper I will provide a brief overview of the development of vaccine-induced immunity by inactivated and live vaccines, current traditional vaccines and the current state-of-the-art of recombinant vaccines.