Uncovering secrets of nature`s primitive immune system

Washington: Scientists claim to
be uncovering the secrets of one of nature`s most primitive
immune systems through studying how bacteria incorporate
foreign DNA from invading viruses into their own regulatory.

A team at Texas A&M University, led by Thomas Wood,
has shed light on how bacteria have throughout the course of
millions of years developed resistance to antibiotics by co-
opting the DNA of their natural enemies -- viruses.

According to Wood, the battle between bacteria
and bacteria-eating viruses has been going on for millions of
years, with viruses attempting to replicate themselves by --
in one approach -- invading bacteria cells and integrating
themselves into the chromosomes of the bacteria.

When this happens a bacterium makes a copy of its
chromosome, which includes the virus particle. The virus then
can choose at a later time to replicate itself, killing the
bacterium -- similar to a ticking time bomb, he said.

However, things can go radically wrong for the virus
because of random but abundant mutations that occur within the
chromosome of the bacterium.

With this new diverse blend of genetic material, a
bacterium not only overcomes the virus` lethal intentions but
also flourishes at a greater rate than similar bacteria that
have not incorporated viral DNA, say the scientists.

"Over millions of years, this virus becomes a
normal part of the bacterium. It brings in new tricks, new
genes, new proteins, new enzymes, new things that it can do.
The bacterium learns how to do things from this.

"What we have found is that with this new
viral DNA that has been trapped over millions of years in the
chromosome, the cell has created a new immune system.

"It has developed new proteins that have enabled it
to resists antibiotics and other harmful things that attempt
to oxidise cells, such as hydrogen peroxide. These cells that
have the new viral set of tricks don`t die or don`t die as
rapidly," Wood said.


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