title: Bivalent vaccination against pneumonic pasteurellosis in domestic sheep and goats with modified-live in-frame lktA deletion mutants of Mannheimia haemolytica.
abstract: A temperature-sensitive shuttle vector, pBB80C, was utilized to generate in-frame deletion mutants of the leukotoxin structural gene (lktA) of Mannheimia haemolytica serotypes 1, 2, 5, 6, 7, 8, 9, and 12. Culture supernatants from the mutants contained a truncated protein with an approximate molecular weight of 66 kDa which was reactive to anti-leukotoxin monoclonal antibody. No protein reactive to anti-LktA monoclonal antibody was detected at the molecular weight 100-105 kDa of native LktA. Sheep and goats vaccinated intramuscularly with a mixture of serotypes 5 and 6 mutants were resistant to virulent challenge with a mixture of the wild-type parent strains. These vaccinates responded serologically to both vaccine serotypes and exhibited markedly-reduced lung lesion volume and pulmonary infectious load compared to control animals. Control animals yielded a mixture of serotypes from lung lobes, but the proportion even within an individual animal varied widely from 95% serotype 5-95% serotype 6. Cultures recovered from liver were homogeneous, but two animals yielded serotype 5 and the other two yielded serotype 6 in pure culture.
authors.affiliation: US Department of Agriculture, National Animal Disease Center, 1920 Dayton Avenue, Ames, IA 50010, USA. Electronic address: robert.briggs@ars.usda.gov.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Briggs
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Hauglund
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Maheswaran
authors.forename: Fred M
authors.initials: FM
authors.lastname: Tatum
mesh_terms: D000818:Animals; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000235:genetics; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D015511:Goat Diseases / Q000517:prevention & control*; D006041:Goats; D006460:Hemolysin Proteins / Q000235:genetics; D007273:Injections, Intramuscular; D008168:Lung / Q000382:microbiology / Q000473:pathology; D016978:Mannheimia haemolytica / Q000235:genetics / Q000276:immunology*; D012766:Pasteurellosis, Pneumonic / Q000517:prevention & control*; D017384:Sequence Deletion; D012756:Sheep; D012757:Sheep Diseases / Q000517:prevention & control*; D034561:Sheep, Domestic; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D006460:Hemolysin Proteins; D014613:Vaccines, Attenuated; C102677:lktA protein, bacteria
keywords: Leukotoxin; Mannheimia haemolytica; Pneumonia; Respiratory disease; Vaccination