title: Use of a polymerase chain reaction method to detect the leukotoxin gene lktA in biogroup and biovariant isolates of Pasteurella haemolytica and P trehalosi.
abstract: OBJECTIVE
  To determine whether Pasteurella haemolytica and P trehalosi isolates possess the structural gene for Pasteurella leukotoxin lktA and whether beta-hemolytic activity of these isolates correlated with detection of the lktA gene.
  
  
  METHODS
  147 P haemolytica isolates from 21 biovariant groups and 101 P trehalosi isolates from 7 biovariant groups. In addition, P multocida and organisms from 7 other genera were tested to establish specificity of the procedure.
  
  
  METHODS
  Isolates were observed for beta-hemolysis. A polymerase chain reaction (PCR) procedure was used to amplify the RTX domain of the Pasteurella lktA gene.
  
  
  RESULTS
  The lktA gene was detected in 108 (44%) isolates, including 15 associated with respiratory tract disease. All but 2 (98%) of the isolates that had the lktA gene were beta-hemolytic when grown on sheep blood agar. The remaining 140 isolates were negative for the lktA gene and hemolytic activity.
  
  
  CONCLUSIONS
  Hemolytic activity of P haemolytica and P trehalosi isolates correlated with detection of the lktA gene for all but 2 isolates. However, 56% of isolates tested were negative for the lktA gene and beta-hemolytic activity. Leukotoxin production and secretion is a major virulence factor when other conditions are favorable for disease development. Therefore, identification of strains that possess the lktA gene may aid in the evaluation of the pathogenic potential of Pasteurella strains carried by wild and domestic animals.
authors.affiliation: Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Fisher
authors.forename: G C
authors.initials: GC
authors.lastname: Weiser
authors.forename: D L
authors.initials: DL
authors.lastname: Hunter
authors.forename: A C
authors.initials: AC
authors.lastname: Ward
mesh_terms: D000818:Animals; D001426:Bacterial Proteins; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis; D003670:Deer; D005098:Exotoxins / Q000235:genetics*; D015511:Goat Diseases / Q000175:diagnosis; D006041:Goats; D006460:Hemolysin Proteins / Q000235:genetics*; D016978:Mannheimia haemolytica / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D010325:Pasteurella / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D010326:Pasteurella Infections / Q000175:diagnosis / Q000662:veterinary*; D016133:Polymerase Chain Reaction / Q000379:methods; D012756:Sheep; D012757:Sheep Diseases / Q000175:diagnosis; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins; D005098:Exotoxins; D006460:Hemolysin Proteins; C102677:lktA protein, bacteria