Type of Document	Master's Thesis
Author	Boudreaux, Charles Mitchell
Author's Email Address	cboudreaux@agctr.lsu.edu
URN	etd-07012004-101913
Title	A Novel Strategy of Controlling Bovine Pneumonic Pasteurellosis: Transfecting the Upper Respiratory Tract of Cattle with a Gene Coding for the Antimicrobial Peptide Cecropin B
Degree	Master of Science (M.S.)
Department	Veterinary Microbiology & Parasitology (Veterinary Medical Sciences)
Advisory Committee	Advisor Name Title Richard Corstvet Committee Chair Frederick Enright Committee Member Marjorie Gill Committee Member Richard Cooper Committee Member
Keywords	gene transfer
Date of Defense	2004-06-10
Availability	unrestricted
Abstract The very potent antibacterial activity of cecropin B makes it a likely candidate to prevent and/or treat Mannheimia haemolytica 1:A infection in the upper respiratory tract (URT) of cattle. The purpose of this study was to ascertain if the URT could be transfected with a gene coding for the antimicrobial peptide cecropin B. By transfecting cattle with a gene coding for cecropin B, this study attempted to inhibit colonization of a virulent strain of M. haemolytica 1:A in the URT while investigating any possible changes in the indigenous and transient nasal flora. In this study the antibacterial efficacy of cecropin B for a virulent strain of M. haemolytica 1:A was determined. In vitro results showed that cecropin B was very effective in inhibiting this virulent strain of M. haemolytica 1:A within 20 minutes of incubation at 37°C. No inhibition of its activity was observed by incubating cecropin B in pooled bovine nasal secretions. The nasal passages of calves were aerosolized with different amounts of plasmid DNA containing a gene coding for cecropin B. Results of this study show that calves transfected with 50 or 100 μg of plasmid DNA per nostril were able to express cecropin B at the mRNA and peptide level. Detection of the cecropin B gene in control calves may indicate the possibility of native bovine cecropin. After challenge with a virulent strain of M. haemolytica 1:A, all calves were stressed by transportation in a crowded trailer 100 miles for 3 hours. Seven out of the 8 control calves yielded detectible levels of M. haemolytica 1:A in nasal aspirates throughout the weeks following challenge. All 4 calves given 25 μg of plasmid DNA per nostril and two of the 4 calves given 50 μg of plasmid DNA per nostril yielded detectible levels of M. haemolytica 1:A in nasal aspirates following challenge. However, M. haemolytica 1:A was not detected in any calf given 100 μg of plasmid DNA per nostril. There appeared to be no change in the normal bacterial nasal flora.
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