Applications of Biotechnology in Health and Medicine

• Biotechnology is applied broadly across health, agriculture, industry, environment, and genomics.
• In the field of health, biotechnology covers diagnostics, vaccines, stem cells, genetic counselling, forensic applications, gene probes, genetic fingerprinting, and karyotyping.
• Recombinant DNA technology enables the mass production of safe therapeutic proteins that avoid the unwanted immune responses associated with animal-derived products.
• Approximately 30 recombinant therapeutics are approved globally; 12 are marketed in India.

Structure of Insulin:

• Proinsulin is the precursor form containing three segments: A chain, B chain, and a connecting C peptide.
• Active insulin consists only of the A chain (21 amino acids) and B chain (30 amino acids), joined by disulphide bonds; the C peptide is removed during processing.

Maturation of pro-insulin into insulin

Why Animal Insulin Was Replaced?

• Insulin was earlier extracted from cattle and pig pancreas.
• Some patients developed allergic or immune reactions to animal insulin.
• Recombinant insulin is identical to human insulin - safe and reaction-free.

Production Steps:

• The gene sequences for the A chain and B chain are isolated separately.
• Each gene is inserted individually into plasmid pBR322, fused with the β-galactosidase (lacZ) gene of E. coli.
• Recombinant plasmids are transformed into E. coli cells, which express fusion proteins (β-galactosidase + respective insulin chain).
• Fusion proteins are extracted, cleaved, and the A chain and B chain are purified independently.
• Both chains are combined in vitro under oxidising conditions → disulphide bonds form → biologically active Humulin.

A vaccine stimulates the immune system to produce immunity against a specific pathogen without causing disease. A recombinant/subunit vaccine uses a specific antigen protein of the pathogen, produced via rDNA technology.

Types of Vaccines:

• A transgenic plant is engineered to express a pathogen antigen; consuming the plant delivers the antigen to immune cells via the gut.
• Stimulates both mucosal immunity and systemic immunity - no injection needed.
• Cost-effective, no cold chain required, easy to administer.
• First edible vaccine: developed in tobacco against Hepatitis B surface antigen (HBsAg) using the 'S' gene of HBV.
• Other targets: rotavirus, dengue, HPV, and influenza.

Gene therapy delivers a functional copy of a defective gene into a patient's cells to correct a genetic disorder. The ex vivo approach involves modifying cells outside the body and reintroducing them.

ADA Deficiency:

• ADA (Adenosine Deaminase) is an enzyme essential for normal immune function.
• A defective or absent ADA gene causes accumulation of toxic metabolites that destroy lymphocytes → SCID (Severe Combined Immunodeficiency Disease).

Steps of Gene Therapy:

• Lymphocytes are extracted from the patient's bone marrow and cultured in vitro.
• A functional ADA gene is introduced into the cultured lymphocytes using a retroviral vector.
• Genetically corrected lymphocytes are infused back into the patient's bloodstream.
• The corrected lymphocytes produce functional ADA enzyme, restoring immune function.
• Periodic infusions are required because lymphocytes are not self-renewing - they have a limited lifespan.

Molecular diagnostics detect a pathogen or genetic mutation at the nucleic acid or protein level - enabling diagnosis before symptoms appear.

Why Conventional Methods Are Insufficient?

• A pathogen present in very low concentration cannot be detected by routine culture or serological methods.
• By the time symptoms appear, the pathogen has already multiplied significantly, delaying effective treatment.

Diagnostic Tools:

• PCR can detect the pathogen's nucleic acid even from a single molecule, making it the most sensitive tool.
• ELISA is widely used for mass screening due to its speed and reliability.
• DNA probes identify the presence of a specific gene through complementary base pairing.

• Recombinant DNA technology allows for the mass production of safe therapeutic proteins, eliminating the allergic reactions associated with earlier animal-derived medicines.
• Genetically engineered human insulin is produced by separately synthesising the A and B chains in E. coli and linking them with disulphide bonds.
• Biotechnology facilitates the development of recombinant subunit vaccines, which use specific pathogen antigens to safely stimulate the immune system.
• Transgenic plants can be engineered to produce cost-effective edible vaccines that deliver injection-free mucosal and systemic immunity upon consumption.
• Gene therapy treats genetic disorders like ADA deficiency (SCID) by using retroviral vectors to insert a functional gene into a patient's extracted lymphocytes.
• Patients receiving gene therapy for ADA deficiency require periodic infusions of genetically corrected lymphocytes because these cells have a limited lifespan.
• Polymerase Chain Reaction (PCR) is a highly sensitive molecular diagnostic tool that amplifies trace amounts of DNA or RNA to detect diseases before clinical symptoms arise.
• Molecular diagnostics also use ELISA for mass screening via antigen-antibody reactions and DNA probes to detect specific genetic mutations through hybridisation.