Killer bugs tamed with a dose of the Arctic

18 July 2010
Posted by Chris Smith.

Scientists have found a way to tame hostile bacteria and turn them into docile vaccines, by replacing key genes with those from the bugs Arctic counterparts!

Writing in PNAS, University of Victoria, Canada, researcher Barry Duplantis and his colleagues reasoned that some of the essential genes carried by bacteria that have evolved over billions of years to live in very cold climes will most likely be optimised to those temperatures.  So exchanging some of these genes for their equivalents carried by warmth-favouring pathogenic bacteria could produce a temperature-intolerant, disabled bug that could function as an ideal vaccine.

Salmonella bacteriaTo find out, the team tested out nine genes known to be critical to survival in all known bacterium; the gene sequences were first "cloned" from bacteria that flourish in the Arctic and then inserted into the chromosomes of Salmonella and Francisella bacteria and also a Mycobacterial species related to TB, replacing the native gene.

The modified bugs grew unhindered at low temperatures, but grown at higher temperatures the bacteria suffered stunted growth.  Injected into a cool spot on the bodies of experimental rodents, the modified bugs, which are usually fatal, instead provoked a robust immune response allowing the animals to fend off a lethal dose of unmodified bacteria which were administered a few weeks later.

This suggests that the technique could be used to produce a host of safe, temperature-sensitive live vaccines capable of protecting people against significant pathogens including Salmonella and TB.

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