ATTENUATED MANNHEIMIA HAEMOLYTICA STRAINS
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.