Attenuated Mannheimia haemolytica Vaccines and Methods of Making and Use

Abstract

The present invention provides attenuated M. haemolytica strains that elicit an immune response in animals against M. haemolytica, compositions comprising said strains, methods of vaccination against M. haemolytica, 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 . A vaccine comprising an attenuated  Mannheimia haemolytica  ( M. haemolytica ) A1 strain and an attenuated  M. haemolytica  A6 strain, which vaccine provides a safe and protective immune response in a bovine against both  M. haemolytica  strain A1 and  M. haemolytica  strain A6 , or diseases caused by  M. haemolytica  strains A1 and A6 ; and 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. 
     
     
         2 . The vaccine of  claim 1 , consisting essentially of the attenuated strains. 
     
     
         3 . The vaccine of  claim 1 , further comprising an adjuvant. 
     
     
         4 . The vaccine of  claim 1 , wherein the attenuated strains each comprise a gene having the sequence as set forth in SEQ ID NO:16. 
     
     
         5 . The vaccine of  claim 1 , wherein the attenuated strains each comprise a gene having the sequence as set forth in SEQ ID NO:17. 
     
     
         6 . The vaccine of  claim 1 , wherein a safe and protective intranasal dose of the vaccine comprises from about 1.19×10 6  to 1.19×10 7  CFU of the attenuated A1 strain and from about 9.2×10 5  to 9.2×10 5  CFU of the attenuated A6 strain. 
     
     
         7 . The vaccine of  claim 6 , further comprising a pharmaceutically or veterinary acceptable vehicle, diluent or excipient. 
     
     
         8 . The vaccine of  claim 7 , further comprising an adjuvant. 
     
     
         9 . The vaccine of  claim 8 , wherein the adjuvant is an inactivated bacterium, an inactivated virus, a fraction of an inactivated bacterium, a bacterial lipopolysaccharide, a bacterial toxin, or a derivative or combination thereof. 
     
     
         10 . The vaccine of  claim 6 , which provides a protective immune response in a bovine against an experimental challenge of about 2.4×10 9  CFU of virulent  M. haemolytica  strain A1. 
     
     
         11 . The vaccine of  claim 1 , further comprising at least one additional antigen associated with a bovine pathogen other than  M. haemolytica.    
     
     
         12 . The vaccine of  claim 11 , wherein the at least one additional antigen is capable of eliciting in a bovine an immune response against bovine pathogen other than  M. haemolytica.    
     
     
         13 . A method of vaccinating an animal, comprising administering at least one dose of the vaccine of  claim 1 . 
     
     
         14 . The method of  claim 13 , wherein the animal is a bovine. 
     
     
         15 . The method of  claim 14 , wherein the bovine is a calf that is 28 days or older. 
     
     
         16 . An immunological composition suitable for the prevention of bovine respiratory disease caused by  M. haemolytica,  comprising the vaccine of  claim 1 , and further comprising an immunologically effective amount of attenuated  Pasteurella multocida  and  Haemophilus somni.    
     
     
         17 . The method of  claim 13 , wherein the vaccine is administered intranasally. 
     
     
         18 . A mixture of two deletion mutant bacteria, wherein each deletion mutant bacterium has a deletion within the LktCA gene locus encoding acylase (LktC) and leukotoxin A (LktA), wherein a first deletion mutant bacterium is an  M. haemolytica  A1 bacterium and a second mutant bacterium is an  M. haemolytica  A6 bacterium. 
     
     
         19 . The mixture of  claim 18 , wherein the deletion mutant bacteria secrete a truncated form of the LktA protein having an amino acid sequence encoded by the nucleic acid sequence as set forth in SEQ ID NO:16 or 17. 
     
     
         20 . The mixture of  claim 19 , wherein the truncated form of the LktA protein is encoded by the nucleic acid sequence as set forth in SEQ ID NO:17. 
     
     
         21 . The method of  claim 13 , wherein the vaccine consists essentially of the attenuated strains. 
     
     
         22 . The method of  claim 13 , wherein the vaccine further comprises an adjuvant. 
     
     
         23 . The method of  claim 13 , wherein the attenuated strains each comprise a gene having the sequence as set forth in SEQ ID NO:16. 
     
     
         24 . The method of  claim 13 , wherein the attenuated strains each comprise a gene having the sequence as set forth in SEQ ID NO:17.