Transgenic animals –

Animals whose DNA is manipulated to possess and express an extra gene are known as transgenic animals. Transgenic rats, rabbits, pigs, sheep, and cows have been produced.

Following are the common reasons for developing transgenic animals :-

1. Study of normal physiology and development

• Useful to study gene regulation, their effect on the normal functions of the body and its development.
• For example, study of complex growth factors like insulin- like growth factor.

2. Study of disease

• Study of genes which are responsible for disease in human and their treatment.
• Transgenic models have been developed for many human disease like cancer, fibrosis, rheumatoid arthritis and Alzheimer’s disease.

3. Biological products

• Useful biological products can be produced by introducing, into transgenic animals, the portion of DNA ( or genes) which codes.
• For example, human protein a-1 antitrypsin is used to treat emphysema.
• In 1997, the first transgenic cow , Rosie, produced human protein- enriched milk (2.4 g/L).
• The milk contained the human alpha – lactalbumin and was more nutritionally balanced for human babies that natural cow milk.

4.Vaccine safety

• Transgenic mice are developed to test safety of vaccines, before being used on humans.
• For example, polio vaccines.