10.1.4 Recombinant Vaccines

. . Recombinant Vaccines Recombinant DNA technology has been used to produce new generation vaccines. The limitations of traditional vaccine production could be overcome by this approach. The recombinant vaccines are generally of uniform quality and produce less side effects as compared to the vaccines produced by conventional methods. Different types of recombinant vaccines include subunit recombinant vaccines, attenuated recombinant vaccines and DNA vaccines. Subunit recombinant vaccines Vaccines that use components of a pathogenic organism rather than the whole organism are called subunit vaccines ; recombinant DNA technology is very suited for developing new subunit vaccines. It includes components like proteins, peptides and DNAs of pathogenic organisms. The advantages of these vaccines include their purity in preparation, stability and safe use. Attenuated recombinant vaccines This includes genetically modified pathogenic organisms (bacteria or viruses) that are made nonpathogenic and are used as vaccines. It is now possible to genetically engineer the organisms (bacteria or viruses) and use them as live vaccines and such vaccines are referred to as attenuated recombinant vaccines. XII Std Zoology Chapter XII Std Zoology Chapter Applications of Biotechnology a target animal. DNA instructs the cells to make antigenic molecules which are displayed on its surfaces. This would evoke an antibody response to the free floating antigen secreted by the cells. The DNA vaccine cannot c ause the disease as it contains only copies of a few of its genes. DNA vaccines are relatively easy and inexpensive to design an d produce. Vaccines produced by these new techniques have definite advantages like producing target proteins, long lasting immunity and trigger immune response only against specific pathogens with less toxic effects. Recombinant hepatitis B vaccine is a subunit vaccine. It is produced by combining Hb (Hepatitis B Virus) antigen producing gene in a plasmid DNA obtained from a bacteria. The resultant recombinant DNA is cloned in the yeast, Saccharomyces cerevisiae (Fig. . ) . Edible vaccines are prepared by molecular pharming using the science of genetic engineering. Selected genes are introduced into plants and the transgenic plants are induced to manufacture the encoded protein. Edible vaccines are mucosal targeted vaccines which cause stimulation of both systemic and mucosal immune response. At present edible vaccines for measles, cholera, foot and mouth disease and hepatitis are tested on animals and under develolpmental phase. DNA Vaccines Genetic immunisation by using DNA vaccines is a novel approach that came into being in . The immune response of the body is stimulated by a DNA molecule. A DNA vaccine consists of a gene encoding an antigenic protein, inserted onto a plasmid, and then incorporated into the cells in Hepatitis B Virus Recombinant Bacterium HB antigen producing gene Fermentation Tank Recombinant DNA Plasmid DNA Bacterial DNA Bacterium Plasmid DNA cut with restriction enzymes HB antigen DNA Extraction & purification of HB vaccine HB vaccine Recombinant yeast cell multiplying and producing HB antigen in fermentation tank