(i) Dolly – The first cloned animal Using nuclear transfer technique, the world’s first mammalian clone – Dolly, was born in February 1996. In 1995, Ian Wilmut and his research group (Scotland) took out udder from a six year old sheep A called clone mother, and put in a special solution. Nucleus of udder cell was taken out and put in a solution. At the same time an unfertilized egg was taken out from another sheep B called egg mother. Nucleus of the egg was removed and nucleated egg was put in a culture medium. The nucleus of udder cell and nucleated egg cell were put together followed by mild electric shock. Consequently nucleus was taken up by the nucleated cell. This cell was incubated onto growth medium then transferred into a surrogate mother. A little lamb Dolly was born in February, 1996.
(ii) It is true that proteins (vaccines) stimulate immune system and cause to secrete specific antibodies. Such specific amino acid sequences in the protein that stimulate immune response are called epitopes. Based on selected epitopes recombinant vaccines may be produced on commercial level which can prove more effective and safer than the conventional vaccines.
Working on these lines, a recombinant Hepatitis B vaccine was produced by cloning the synthetic gene (for the surface antigen of the virus) in yeast cells. This gene expressed well in yeast cells and produced 22 nm particles of hepatitis B virus (HBV) surface antigen (as produced in patients) infected with hepatitis B virus. The recombinant vaccine has high immunogenecity. This product has been marketed as a vaccine for protection against HBV infection.
