DIAGNOSIS OF DISEASES AND GENE THERAPY

INTRODUCTION Most developments in biotechnology originated for their potential applications in health care. Contribution of biotechnology: Diagnosis of diseases Therapeutic agents Correction of genetic disease-Gene therapy Fertility control Forensic medicine

DIAGNOSIS OF DISEASE Disease prevention Disease detection Therapeutic agents Correction of genetic diseases Fertility control Forensic medicine

PROPERTIES OF IDEAL VACCINE Should not be toxic or pathogenic. Should have very low levels of side effect. Should not cause problems in individual with a weak immune system. Should not contaminate the environment. Technique of vaccine should be simple. Should have long-term effect. Should be cheap so that is generally affordable.

TYPES OF VACCINES CONVENTIONAL VACCINES Live vaccines Inactivated pathogen PURIFIED ANTIGEN VACCINES RECOMBINANT VACCINES Recombinant protein or Subunit molecule Whole protein molecule Polypeptide DNA vaccine

STEPS FOR DISEASE DIAGNOSIS Microscopic examination of specimen. Culture of the specimen to allow specific pathogens to grow. Immunologic assays for specific antigens present on the surface of pathogens. Detection and measurement of the pathogen-specific antibodies produced by the patient in response to the invasion by pathogen.

NOVEL DIAGNOSTIC APPROACHES DNA/RNA Probes : Small nucleotide sequence used to detect the presence of complementary sequence in nucleic acid samples. Both RNA and DNA are used as probes. ADVANTAGES: Highly specific, relatively rapid and much simpler. Extremely powerful when combined with PCR. Applicable to such organisms which could be cultured, pure probes are easily available.

PCR

NOVEL DIAGNOSIS APPROACHES Monoclonal Antibodies: Specific antigenic determinant of a single antigen. Auto antibodies: specific to those antigens, which are normally tolerated by immune system and are typically constituents of cells and tissues of the animal in question; such antigens are called autoantigens.

NOVEL DIAGNOSIS APPROACHES Commercial Potential Of Diagnostics: Diagnostic is a tool that greatly facilitates an accurate diagnosis of a health condition. Detection Of Genetic Diseases: Genetic diseases are generally produced by single recessive mutagen. Identification of the gene responsible for genetic disease is very important. The foetal cells are used for detection of genetic disorder.

DISEASE TREATMENT Treatment of disease utilizes a wide variety of preparation of both biological and abiological origins. Products From Non-Recombinant Organisms: Microorganisms Plant cell cultures Animal cell cultures Product From Recombinant Organisms: Genetically engineered microorganisms. Ex: production of human insulin, production of human growth hormone. Animal cell cultures. Ex: HGH, tissue plasminogen activator, erythropoietin (anemia), blood clotting factor 8 (Haemophilia). Transgenic plants. Ex: Bt cotton, Bt corn, golden rice.

BT CORN

Gene Therapy Introduction of a normal functional gene into cells which contain the defective allele of concerned gene with the objective of correcting a genetic disorder or an acquired disorder. It also includes the attempts to cure any disease by the introduction of a cloned gene into the patient.

APPLICATIONS OF GENE THERAPY Identification of the gene that plays a key role in the development of genetic disorder. Determination of the role of its product in health and disease. Isolation and cloning of gene. Development of an approach for gene therapy.

TYPES OF GENE THERAPY Germ-Line Gene Therapy Somatic Cell Gene Therapy Additional/Augmentation Gene Therapy Targetted Gene Transfer

GERM-LINE GENE THERAPY Germ cells i.e. sperms or eggs are modified by the introduction of function genes which are integrated into their genomes. The change due to therapy would be heritable and would be passed onto later generations.

SOMATIC CELL GENE THERAPY The gene is introduced only in somatic cells especially of those tissues in which expression of the concerned gene is critical for health . This therapy eliminates the symptoms of the disorder but this effect is not heritable. Two divisions: Addition/Augmentation Gene Therapy Targetted Gene Transfer

ADDITONAL/AUGMENTATION GENE THERAPY The functional gene is introduced in additon to the defective gene endogenous to the cell i.e. the modified cells contain both the detective as well as the normal copies of the gene. There were two approaches to augmentation therapy. The first approach was used in the first two patients on whom gene therapy was detected to correct the genetic disorder called SCID syndrome produced by ADA defeciency.

SCID SYNDROME PRODUCED BY ADA DEFICIENCY Normal ADA gene copies were produced by cloning. They were packed in defective retrovirus, most of the viral genes were replaced by the ADA gene. Lymphocytes were isolated from the patients. The recombinant retroviruses were used to infect the lymphocytes. The infected cells expressing the ADA Gene were injected back into the pateint.

INJECTION OF DNA The second approach is the direct injection of DNA into the tissues either as protein complexes or even as naked DNA into muscle or skin. These cells take up DNA and express the gene product.

TARGETTED GENE TRANSFER It uses homologous recombination to replace the endogenous gene with the functional introduced gene. The first case of such a gene transfer was used to disrupt the human Beta- globin gene in cultured cells. Can be used either to inactivate a functional endogenous gene or to correct a defective one. Two types of vectors employed: Insertion vector Replacement vector

ETHICAL ISSUES Who makes the decision that a given individual should be tested? Should the individual be informed about the findings from the test? Should the result from the genetic tests be made available to insurance companies, employers etc. ? Even when the individual has the mutant allele responsible for a genetic disease, what is the likelihood that this allele will be able to express itself? If a foetus has a genetic disease that will become manifest at the age of , say, 50 years, should the foetus be aborted? There is a genuine fear that individuals having genetic disorders may be discriminated against There are doubts that the result from genetic testing may not always be reliable.