Bath, Exeter: Technique for identifying essential genes in bacteria

Research lead

Scientists from the universities of Bath and Exeter, UK, have developed a rapid new way of identifying essential genes in disease-causing bacteria which infect insects and humans. The findings could lead to new vaccines and anti-bacterial drugs.

The researchers worked with Photorhabdus asymbiotica, a bacterium that normally infects and kills insects, but which can also cause an unpleasant infection in humans.

By testing groups of genes from the bacteria in insects, worms, amoebae and mammalian cells, the scientists identified toxins called virulence factors made by the bacteria that allow it to infect each type of organism. They then identified the genes responsible for each of these possible virulence factors and compared them with the genes of well-known bacteria, to map out which regions of the bacterium’s DNA control its ability to infect and damage invertebrates, and also potentially humans.

One of the researchers, Maria Sanchez-Contreras, said identifying the genes responsible for the production and secretion of bacterial toxins will open up ways to prevent disease.

“Our new technique, called Rapid Virulence Annotation (RVA), allows us to make faster assessments of the disease-causing agents in multiple types of organism; it lets us pinpoint sequences of genes which may pose a risk to humans; and it gives us a powerful tool to identify virulence genes in other known bacteria.

“Finally, it helps us identify new targets for drugs to fight these diseases and control pests, and for developing preventive vaccines.”

Richard ffrench-Constant, professor of insect microbiology, said, “RVA allows us to look for virulence factors that are totally novel and does not rely upon traditional searches based on factors already known from other bacteria. We have already discovered that some totally unexpected genes are indeed involved in bacterial virulence. This technique should prove to be a gold mine for potential vaccine candidates.”

The scientists are already using this relatively cheap and highly accurate RVA technique in other disease-causing bacteria to identify the genes that allow some diseases to jump the species barrier.