Recombinant DNA Technology : A Short Communication

biotechnology [3,4,5]. In the field of medicine, it has resulted in development of newer antibiotics, vaccines for various diseases such as cancer, AIDS, hereditary diseases such as Huntington’s chorea etc. Biotechnology is also being applied in the area of pollution control, mining and energy production (biofuel production). Genetically engineered micro-organism and plants are used to clean up toxic wastes from industrial effluents and oil spills.


Introduction
The term biotechnology is a fusion of biology and technology.The area is multidisciplinary, vast and highly divergent, which has made a precise definition of the subject rather difficult.
It is basically the controlled use of biological agents, such as microorganisms or cellular components for human beneficial use.It is the integrated use of biochemistry, microbiology and engineering sciences in order to exploit microorganisms, cultured tissues/cells, to their best [1,2].Man has continued his quest for improving the natural capabilities of microorganisms and making them capable of novel processes and to create them for highly valuable cause, for human welfare.Years ago, people exploited micro-organisms for making bread, brewing alcohol and cheese production, although the phenomenon of fermentation was not understood thoroughly.Now, the extent of biotechnological application is more sophisticated.Researchers can manipulate living organisms and transfer genetic material between organisms, generating transgenics (plants/animals).The current applications of biotechnology are predominantly practiced in the field of agriculture and medicine.Modern techniques allow production of new and improved foods.Insect resistant crops have been developed using recent advances in material into the host cell as part of their replication cycle.Therefore this has been recognized as a plausible strategy for gene therapy, by removing the viral DNA and using the virus as a vehicle to deliver the therapeutic DNA.A number of viruses have been used for human gene therapy, including retrovirus, adenovirus, lentivirus, herpes simplex virus, vaccinia, pox virus, and adeno-associated virus [11,12,13].

Gene therapy
It has important implications in treatment of acquired and genetic diseases, cancer and possibly AIDS.It is classified into two types: Germ line gene therapy: Germ cells (sperm or eggs) are modified by the introduction of functional genes.Therefore, the change is heritable and will be passed on to the later generations.This is theoretically highly effective in treating genetic disorders but this option is not considered at present for application in human beings for a variety of ethical reasons.

Somatic gene therapy:
The gene is introduced only in somatic cells but it is not herited as germline is not involved.Somatic gene therapy is further divided into two groups: The first one where the functional gene is introduced in addition to the defective gene endogenously that is the modified cell contains both the defective as well as the normal (introduced) copies of the gene.This is called as augmentation therapy.The second is targeted gene transfer, which uses homologous recombination to replace the endogenous gene with the introduced functional gene [14].

Recombinant Antibodies
Developments in the fields of bacterial expression of functional antibodies and methods to select genes from a library by using the phenotype of the encoded polypeptide have been a breakthrough in antibody technology.Today, phage display in combination with antibody gene libraries is widely used to select E. coli host cells that express desired antibody fragments.Such gene libraries are typically produced either from natural sources (e.g., from the spleen of an immunized animal or from plasma cells of human donors) or generated by genetic engineering.The latter has been used to create naïve libraries based on one or more antibody VH and VL gene segments that are diversified by cassette mutagenesis or similar approaches.Such libraries are typically unbiased and can be used for any given antigen [15].
A vast majority of applications of environmental biotechnology use naturally occurring microorganisms (bacteria, fungi, etc.) to identify and filter manufacturing waste before it is introduced into the environment.Bioremediation program involving the use of microorganisms are currently in progress to clean up contaminated air, tracks of land, lakes and waterways.Recombinant technology helps in improving the efficacy of these processes so that their basic biological processes are more efficient and can degrade more complex chemicals and higher volumes of waste materials.Recombinant DNA technology also is being used in development of bioindicators where bacteria have been genetically modified as 'bioluminescors' that give off light in response to several chemical pollutants.These are being used to measure the presence of some hazardous chemicals in the environment.Other genetic sensors that can be used to detect various chemical contaminants are also undergoing trials and include sensors that can be used to track how pollutants are naturally degrading in ground water.For example when gene such as the mercury resistance gene (mer) or the toluene degradation (tol) gene is linked to genes that code for bioluminescence within living bacterial cells, the biosensor cells can signal extremely low levels of inorganic mercury or toluene that are present in contaminated waters and soils by emitting visible light, which can be measured with fiber-optic fluorometers [16].

Future Perspectives
The future of rDNA products as a human therapeutic is looking good.More than 110 companies are involved in discovery, development and marketing of rDNA products.With the use of rDNA technology three major products has been developed.Insulin determir (Latus, Novo Nordisk, Begsvard, Denmark) for diabetes; calcitonin, for treating osteoporosis (Unigene Laboratories, Fairfield, NJ, USA) and palifermin, a keratinocyte growth factor used for treating mucosites (Amgenwoodland Hills, CA, USA) are undergoing FDA review.
Recent advances in biotechnology have created many legal issues, particularly under the patent system.Patent represents one of several types of intellectual properties; their ownership confers the right to exclude others from benefitting from the tangible products of a proprietary subject matter.The discovery and initial characterization of any rDNA product of potential therapeutics application are followed by its patenting.The normal duration of a patent is 20 years, which starts from the date of filing.Thus the timing assumes importance in terms of the duration for marketing of a product.If the patent is filed too early, the window of opportunity to market the product as well as the size of the market will be smaller.The Biotech Industry Guide would be useful for industrial approval, regulatory clearance to rDNA product and bio safety aspects [17,18,19].It would also provide help to scientists in obtaining patents on their inventions in India.