The drug is a naturally found protein, gamma-interferon, which also has anti-viral and anti-cancerous properties, a scientist at the International Centre for Genetic Engineering and Biotechnology (ICGEB), Navin Khanna, told PTI here.

Khanna and his colleagues have developed a new route to prepare the therapeutic protein artificially. Toxicological studies at Central Drug Research Institute (CDRI) in Lucknow found the protein to be safe for human use, he said, adding ``it can be stored up to six months''.

Two major Indian drug companies have shown interest in commercialising the product and one of them was keen to conduct clinical trial of the protein for multi-drug resistant tuberculosis, he said.

The protein has been developed by cloning and expressing a piece of human interferon gene inside `e. Coli' bacteria. The human gene ischemically synthesised by the ICGEB group.

The e. Coli strain produces the protein in a solidified form which is processed by a novel technique, developed at ICGEB, to get about 97 per cent pure protein. During processing, the solidified protein, a long chain of molecules, is unfolded first. The unfolded chain, in the subsequent step, is manipulated and refolded properly to make it biologically active.

The refolded gamma interferon boosts the activity of macrophages which are the principal defence cells against microbial attack. In fact, a 1989 study carried out by Indira Nath from the department of biochemistry at the All India Institute of Medical Sciences (AIIMS) here, showed administering gamma interferon could help reduce the concentration of leprosy-causing microbes significantly.