Thursday, January 12, 2012

Genomic study of deadly bovine pathogen faciliated by QuickExtract Bacterial Kit

Mannheimia haemolytica is a Gram-negative bacterium associated with bovine respiratory disease complex. During stress, such as a viral infection and/or transportation to the feedlot, the bacterium transforms from benign to deadly, and causes a disease called shipping fever, resulting in losses of more than $1 billion annually in the U.S. Despite its economic importance, there are no specific and accurate genetic markers for this disease.

Researchers at Washington State University (Lawrence PK et al., BMC Genomics 2010, 11:535) performed a three-way comparison between the genomic sequences of three strains of M. haemolytica from cattle and domestic sheep. They extracted total genomic DNA using the QuickExtract Bacterial DNA Extraction Kit, and prepared genomic libraries for sequencing on a Genome Sequencer FLX (Roche). At 20X sequence coverage, the authors identified a number of genes that are unique to each strain. In addition, many high-confidence single nucleotide polymorphisms (hcSNPs) were identified, which will be used to design new arrays to study variation across strains and potentially aid in understanding gene regulation and mode of action. Additional virulence factors included a previously unknown type III secretion system, and CRISPR loci that indicates the potential resistance of M. haemolytica to superinfection by phages. The study also identified various adhesins, containing protein cleavage domains, that could potentially serve as effective vaccine targets.

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