9.1.3 Recombinant Vaccines · Part 2

Applications of Biotechnology normal gene into a person’s cells that carries one or more mutant alleles. Expression of normal gene in the person results in a functional gene product whose action produces a normal phenotype. Delivery of the normal gene is accomplished by using a vector. The main thrust of gene therapy has been directed at correcting single gene mutations as in cystic fibrosis and haemophilia. At present most genetic diseases have no effective treatment and so gene therapy could offer hope for many people. There are two strategies involved in gene therapy namely; Gene augmentation therapy which involves insertion of DNA into the genome to replace the missing gene product and Gene inhibition therapy which involves insertion of the anti sense gene which inhibits the expression of the dominant gene (Fig. . ) . The two approaches to achieve gene therapy are somatic cell and germ line gene therapy . of its genes. DNA vaccines are relatively easy and inexpensive to design and 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. . ) .