Attenuated mannheimia haemolytica strains

Abstract

The present invention provides attenuated M. haemolitica strains that elicit an immune response in animal against M. haemolitica , compositions comprising said strains, methods of vaccination against M. haemolitica , and kits for use with such methods and compositions. The invention further provides multi-valent vaccines, which provide protective immunity when administered in an effective amount to animals susceptible to “shipping fever” or bovine respiratory disease.

1 - 56 . (canceled) 
     
     
         57 . A bacterial composition comprising an attenuated  Mannheimia haemolytica  ( M. haemolytica ) A1 strain and an attenuated  M. haemolytica  A6 strain; wherein both the A1 and A6 strains contain nucleic acid deletions in their respective leukotoxin A (lktA) genes, which deletions have rendered the strains attenuated relative to the virulent parental strains A1 and A6 from which the attenuated strains A1 and A6 were produced. 
     
     
         58 . The bacterial composition of  claim 57 , consisting essentially of the attenuated strains. 
     
     
         59 . The bacterial composition of  claim 57 , further comprising an adjuvant. 
     
     
         60 . The bacterial composition of  claim 57 , wherein said bacterial composition comprises from about 1.19×10 6  to 1.19×10 7  CFU of the attenuated  M. haemolytica  A1 strain and from about 9.2×10 5  to 9.2×10 6  CFU of the attenuated  M. haemolytica  A6 strain. 
     
     
         61 . The bacterial composition of  claim 57 , further comprising a vehicle, diluent or excipient and wherein said bacterial composition comprises from about 1.19×10 6  to 1.19×10 7  CFU of the attenuated  M. haemolytica  A1 strain and from about 9.2×10 5  to 9.2×10 6  CFU of the attenuated  M. haemolytica  A6 strain. 
     
     
         62 . The bacterial composition of  claim 61 , further comprising an adjuvant. 
     
     
         63 . The bacterial composition of  claim 62 , wherein the adjuvant is inactivated bacteria, inactivated virus, fractions of inactivated bacteria, bacterial lipopolysaccharides, bacterial toxins, or derivatives or combinations thereof. 
     
     
         64 . The bacterial composition of  claim 57 , further comprising at least one additional bovine pathogen other than  M. haemolytica.    
     
     
         65 . The bacterial composition of  claim 64 , wherein said at least one additional bovine pathogen other than  M. haemolytica  is selected from the group consisting of  Pasteurella multocida, Histophilus somni , and a combination thereof.