Submitted to: Genome Announcements
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2015
Publication Date: 5/7/2015
Citation: Heaton, M.P., Harhay, G.P., Smith, T.P.L., Bono, J.L., Chitko-McKown, C.G. 2015. Complete closed genome sequences of a Mannheimia haemolytica serotype A1 leukotoxin deletion mutant and its wild-type parent strain. Genome Announcements. 3(3):e00417-15. DOI: 10.1128/genomeA.00417-15.
Interpretive Summary: Mannheimia haemolytica is a bacterial pathogen commonly associated with shipping fever in cattle. This respiratory disease is a serious health problem that affects millions of animals, in herds of all sizes, with losses exceeding 1 billion dollars annually. When cattle become stressed, bacteria residing in back of the nasal cavity may end up in the lungs where they secrete a potent toxin causing severe pneumonia. To understand how this toxin functions, researchers have previously genetically engineered a mutant strain of M. haemolytica bacterium. This mutant can no longer produce toxin and, together with its wild-type parent strain, has been widely used for 20 years to study how the toxin causes disease in cattle. However, the genomic sequences of the wild-type parent strain and its engineered mutant strain were previously unknown. This report identifies all the genes in these two bacterial strains and allows the toxin function to be interpreted in a genomic context and compared to those of other bacteria. Knowledge of how different toxin-producing bacteria cause pneumonia will help identify interventions for reducing the impact of shipping fever, thereby promoting animal welfare while enhancing producer efficiency.
Technical Abstract: Mannheimia haemolytica is a bacterial pathogen associated with bovine respiratory disease complex (BRDC). It secretes a leukotoxin that binds to CD18 on leukocyte membranes and causes acute inflammation and lung injury characteristic of BRDC. We report the complete closed genome sequences of a leukotoxin mutant and its parent strain.