Blacksburg, Va. Researchers at the Virginia Bioinformatics Institute at Virginia Tech and the National Animal Disease Center in Ames, Iowa, and collaborators at 454 Life Sciences of Branford, Conn., have sequenced the genome of Brucella abortus strain S19. Strain S19 is a naturally occurring strain of B. abortus that does not cause disease and was discovered by Dr. John Buck in 1923. It has been used for more than six decades as vaccine that protects cattle against brucellosis, an infectious disease caused by other strains of B. abortus that leads to reproductive failure in livestock.
Scientists have long wanted to know what genetic features make strain S19 suitable for use as a vaccine in cattle because it may hold the secret as to why other Brucella strains cause disease and trigger the abortion of developing embryos in livestock. The researchers have discovered a group of 24 genes that are linked to virulence by making comparisons of the newly available S19 genome sequence to previously sequenced genomes of two virulent strains of B. abortus. The paper "Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes" was published recently in PLoS One (May 2008, Volume 3, Issue 5, e2193).
Oswald Crasta, project director at VBI's Cyberinfrastructure Group and the corresponding author on the paper, remarked: "We have been able to leverage rapid sequencing of the S19 genome on the Roche GS-20 and GS-FLX platforms, and comparative genomics narrowed down the search for Brucella virulence factors to a small group of genes. Of particular interest are four genes that show consistently large sequence differences in S19 compared with two fully sequenced virulent strains." He added: "Further studies are underway to characterize the short list of protein differences that appear to be involved in cellular processes ranging from lipid transport and metabolism to tra
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