In this article we will discuss about the role of biotechnology in the field of healthcare.
A wide range of biological products of human healthcare including polypeptides, proteins, growth factors, hormones, enzymes, vaccines, immuno-regulators, antibodies, etc. can be produced through biotechnology.
1. Human Proteins and Hormones:
There are many human proteins which have long been believed or known to have therapeutic potential and their increased production has been achieved by using recombinant DNA technology (Fig. 25.1).
The gene coding for insulin with two polypeptides has been synthesized. Each synthetic gene was linked to a plasmid near the end of the β-galactosidase gene of E. coli. After the gene expression and the translation of mRNA into protein, the two polypeptides were cleaved from the enzyme and linked to form the complete insulin molecule.
Different workers also synthesized complementary DNA from RNA of rat pancreas with the help of reverse transcriptase which was inserted into pBR 322 plasmid in the middle of the gene for penicillinase. The plasmid also contained the structural genes for pro-insulin. The hybrid protein synthesized in the bacterial cell was penicillinase + pro-insulin from which insulin could be separated by trypsin.
Production of interferon took a vital position when human leucocyte interferon was engineered by yeast cells. A DNA sequence coding for human leucocyte interferon was attached to the yeast alcohol dehydrogenase gene in a plasmid and introduced into cells of Saccharomyces cerevisae.
The first human peptide hormone synthesized in a bacterial cell was somatostatin, which is one of a group of hormones secreted by hypothalamus, controls the release of several hormones from the pituitary.
The synthetic gene has been inserted into the plasmid, expression vector was constructed from the plasmid pBR 322, to which was added the control region and most of the β-galactosidase gene from the bacterial lac operon; and the gene was inserted next to β-galactosidase.
After the plasmid was introduced into the cells of the bacterium E. coli, the hormone was synthesized as a short peptide tail at the end of the enzyme (Fig. 25.2).
With the advent of techniques of recombinant DNA and gene cloning, several other human hormones are being produced on a commercial scale by isolating specific DNA sequences coding for those proteins/hormones. This is likely to enable clinical application and improve economic provision for their utility in several deficiencies.
2. Molecular Farming for Healthcare Products (Vaccine, Antibody):
Transgenic plants can be used as ‘factories’ for production of specialty chemicals and pharmaceuticals like sugars, fatty acids, wax materials as well as antibodies, edible vaccines. The progress is so far reaching that human antibody production through plant seeds has been achieved.
The method involves the introduction of heavy and light chains of immunoglobin genes into microbial vectors. In the next step, these are introduced into the leaf cells of two plants and cultured in vitro for regeneration of the plants. The plants-one containing heavy and the other with light chain are then hybridized.
The hybrid brings light and heavy chains together, to form the complete immunoglobin (IgA + IgB) in the seeds. This hybrid plant can be utilized for large scale production of seeds containing antibody proteins. Even antibodies presumed to be effective against cancer have been secured in tobacco seeds. The method is thus a synthesis of recombinant DNA, in vitro technique and conventional hybridization.
Hepatitis B surface antigen is produced in tobacco, rabies virus glycoprotein is produced in tomato, cholera toxin P-subunit is being produced in potato and tobacco. Transgenic plants are being used as a source of antibodies which provide passive immunization.
One of the recent discoveries in the area of plant biotechnology is the development of oral vaccine utilizing plant systems. The principle involves, the development of transgenic plants, containing subunits of toxic virus sequences or enterotoxin genes of bacteria like E. coli or Vibrio cholerae.
The oral administration of potato or tobacco transgenic tissues led to the development of immunoglobin G and A antibodies. As such, oral administration of plant tissues for production of antibodies in the system is, in effect, a vaccination-the application of vaccine being oral. Such recombinant vaccines may prove to be a cheaper substitute for expensive vaccination, both in terms of production and administration.