Antibodies take ‘evolutionary leaps’ to battle microbes

January 10th, 2009 - 2:50 pm ICT by IANS  

Washington, Jan 10 (IANS) Antibodies take ‘evolutionary leaps’ to battle viruses and bacteria that rapidly evolve with every sneeze, sniffle, and cough, especially during the cold and flu season. A new report shows how our antibodies counter foreign invaders by rearranging their genes and enabling our immune system to help us survive.

When the body encounters a foreign invader, like a virus or bacterium, it immediately begins to find a way to neutralise it by means of cellular or antibody-mediated defences.

Part of the process involves tailoring the genes that code for antibodies to specific viruses or bacteria. Researchers have known that this involves two types of genetic manipulation.

One type changes a single gene at a time, and the other type changes multiple genes at the same time. In the report, scientists from Wayne State University in Detroit describe how multiple genes can be modified simultaneously to make the “evolutionary leap” necessary to stave off infection.

The basic setup of the experiment treated DNA responsible for making antibody molecules with an enzyme, called activation-induced deaminase, while the DNA was being copied by RNA polymerase.

Like a scanner, RNA polymerase moves across the DNA to copy it. When this scanning process moved smoothly, there were either single mutations or no mutations.

When the researchers made the RNA polymerase stall along the DNA (under certain conditions), it caused several mutations at once (cluster mutations) in the DNA, adapting the antibodies for a rapid and effective response to a new microbial invader.

“As the planet warms, infectious diseases may be one the biggest threats to human survival,” said Gerald Weissmann, editor-in-chief of The FASEB (Federation of American Societies for Experimental Biology) Journal that published these findings.

“Nowadays, mosquitoes, parasites and viruses cause diseases in the US that were once isolated to warmer parts of the world. They evolve, and - a la Darwin - so does our immune system each time we meet a new microbial invader,” he said, according to a FASEB release.

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