February 4, 2009

Scientists study Q fever pathogen

U.S. scientists say they have uncovered genetic clues about why some strains of the pathogen that causes Q fever are more virulent than others.

Researchers from the National Institute of Allergy and Infectious Diseases, Texas A&M Health Center and the Virginia Bioinformatics Institute at Virginia Tech compared the sequences of four strains of Coxiella burnetii -- an intracellular bacterium that can cause acute and chronic Q fever in humans.

Q fever is considered one of the most infectious diseases in the world since inhalation of a single bacterium is sufficient to cause infection, the scientists said.

Our results suggest that mobile genetic elements have played a major role in the evolution and function of the C. burnetii genome, said Robert Heinzen, head of the Coxiella Pathogenesis section at NIAID. Recombination between insertion sequence elements or jumping genes appears to have brought about large-scale generation of non-functional genes, a change that may be associated with a more pathogenic lifestyle.

Heinzen added: The results of this study provide a solid foundation upon which we can test a number of hypotheses related to C. burnetii gene function and virulence. This information will prove invaluable as we proceed to dissect, at a molecular level, events associated with Q fever pathogenesis

The findings are reported in the journal Infection and Immunity.