VMC 221: Veterinary Immunology and Serology (1+1)

RECOMBINANT DNA VACCINE

• The immune dominant part of a pathogen is cloned into a vector and pathogen DNA is transcribed and translated within the cells of vaccinated animals.
• Virus proteins have been expressed in bacteria, yeast, mammalian cells, and viruses.
• E. coli cells were first to be used for this purpose but the expressed proteins were not glycosylated, which was a major drawback since many of the immunogenic proteins of viruses such as the envelope glycoproteins, were glycosylated.
• An alternative application of recombinant DNA technology is the production of hybrid virus vaccines. Recombinant technology made some useful safe virus vectors for the expression of protective antigens from potentially harmful infectious agents.
• Compared to the subunit vaccines the vectored vaccines produces good immune responses against various pathogens.
• Poxviruses, adenoviruses, herpes viruses are commonly used as vectors for vaccines.Examples of vector based recombinant vaccine, ND virus in fowl pox virus, Rabies virus in vaccinia virus etc..
• Recombinant hepatitis B vaccine is a licensed vaccine.
• Advantages
  • Use of pathogens can be avoided
  • Unwanted reaction is reduced
  • High immune response.
  • Hybrid virus vaccines are stable and stimulate both cellular and humoral immunity.
  • They are relatively cheap and simple to produce.
• Disadvantages
  • Replication of vector may induce side effects
  • Primary immune responses mounted against vector proteins may generate anti – vector antibodies that blocks booster immunization.