With the Bacillus Calmette-Guerin (BCG) vaccine losing its efficacy against the deadly tuberculosis, Indian scientists now plan to give it a boost by transferring some genes from a soil-living bacterium

By Syed Akbar
Hyderabad: With the Bacillus Calmette-Guerin (BCG) vaccine
losing its efficacy against the deadly tuberculosis, Indian scientists
now plan to give it a boost by transferring some genes from a
soil-living bacterium.

Tuberculosis is caused by a bacterium called Mycobacterium
tuberculosis and its ancestor, Mycobacterium indicus pranii (MIP) that
feeds on decaying material, will help scientists to tame extra drug
resistant TB. MIP, whose genome was sequenced recently, is seen as a
potential harmless bacterium whose genes can be transferred to BCG
strain to deal a deadly blow to tuberculosis, on one hand and leprosy
on the other.

“Several new antigenic proteins that we identified in MIP are
incidentally absent from vaccine strain BCG but present in both
Mycobacterium leprae (leprosy germ) and Mycobacterium tuberculosis. An
exciting idea would be to transfer these genes to BCG by using
biotechnology and to test the resulting vaccine strain against both TB
and leprosy. If it works, that will be massive plus for public health
and disease control in India,” said Prof Anil K Tyagi of the
department of biochemistry, University of Delhi South Campus.

Prof Anil Tyagi and other Indian scientists studied MIP in detail for
the first time. They got several vital biological clues, which can be
used to tame tuberculosis and leprosy, even through a single vaccine.
BCG vaccine, though not intended for leprosy, offers some protection
against the disease.

“We urgently need new drugs, new vaccines and new strategies to
overcome these challenges to public health. The information gained by
our work will thus be used to develop new and effective treatment
involving MIP,” Prof Anil Tyagi added.

MIP is an extremely useful, non-pathogenic organism that demonstrated
protective benefits in different diseases like leprosy, TB, TB-HIV and
different types of cancer in different clinical trials. Moreover, the
application of MIP provided better clinical outcomes and reduced the
time of therapy even in multi drug resistant TB, a particularly
dangerous form of TB where treatment may last for more than two years.

Prof Anil Tyagi said, “We now have an understanding for the first time
as to how mycobacteria acquire specific genes and lose some to attain
their host adapted forms causing infections in a variety of hosts
including humans and animals. The understanding as to what genes were
exchanged to adapt a pathogenic lifestyle is very critical. A step
forward will be to study these genes in detail as they can be
potential new drug targets”.