6-3.1Introduction:

Transgenic science offers the methods for in vitro introduction of DNA fragment(s) into a cell and alters the genome in order to achieve a desired character. Animals whose genomes have been altered by transfer of a gene or introducing an exogenous gene are called transgenic animals. Transgenic animals serve as important model for clinical research as well as bioreactors in pharmaceutical manufacturing sector. The term “transgenic” was first coined by Gordon and Ruddle in 1981 and later adopted to describe broad range of experimental animal models having a specific targeted modification in their genome.

6-3.2Types of transgenic animals:
Transgenic animals can be broadly classified into two categories depending on the modification in the genome.

• Knockout animals:

Transgenic animals produced by replacing the endogenous functional gene with mutated non-functional gene are called knockout animals. In laboratory, knockout mice are generated for clinical studies.

• Knockin animals:

Transgenic animals having exogenous functional gene incorporated to the genome by targeted insertion are termed as knockin animals. Several animal transgenic models have been developed by this approach to use as disease models or in biofarming technology.