BRUCELLOSIS DNA VACCINE

Abstract

Brucellosis is a disease caused by facultative intracellular bacteria of the monospecific genus Brucella melitensis. The invention in one aspect is an immunogenic nucleic acid composition comprising DNA encoding Brucella melitensis Invasion Protein B, a polypeptide with at least 95% identity thereto, or an immunologically active fragment of either of these, and an adjuvant. In another aspect, the invention is a DNA vaccine composition comprising a plasmid vector having DNA encoding a polypeptide as recited above, in which said plasmid vector is adsorbed to a liposome. Other aspects of the invention include methods of inducing an enhanced immune response to Brucella infection in an animal, methods for the differential diagnosis in an animal of brucellosis and vaccination by an immunogenic nucleic acid composition having DNA encoding any of the above-recited polypeptides, and a kit for conducting said differential diagnosis methods.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical representation of the relationship between the protective efficacy of vaccination and the generation of antigen specific IFN-γ secreting effector cells.

FIG. 2 is a graphical representation of the relationship between the protective efficacy of vaccination and the generation of specific antibodies.

FIG. 3 is a graphical representation of the relationship between the protective efficacy of vaccination and the number of antigen specific effector cells detected post-challenge.

Claims

1. An immunogenic nucleic acid composition comprising DNA encoding a polypeptide selected from the group consisting of (i) Brucella melitensis Invasion Protein B having an amino acid sequence as shown in SEQ ID NO:12; (ii) a polypeptide having at least 95% sequence identity to (i); and (iii) an immunologically active fragment of (i) or (ii), and an adjuvant, wherein said adjuvant is a liposome.

2. A DNA composition comprising a plasmid vector having DNA encoding a polypeptide selected from the group consisting of (i) Brucella melitensis Invasion Protein B having an amino acid sequence as shown in SEQ ID NO:12; (ii) a polypeptide having at least 95% sequence identity to (i); and (iii) an immunologically active fragment of (i) or (ii), in which said plasmid vector is adsorbed to a liposome.

3. The composition of claims 1 or 2, which when administered to an animal subject induces an immune response that is characterized by enhancement of T cell priming and/or antibody generation compared with an immune response induced by a naked DNA construct encoding the corresponding polypeptide selected from the group consisting of (i), (ii), and (iii).

4. The composition of claims 1 or 2, wherein said liposome is a cationic liposome.

5. The composition of claims 1 or 2, wherein said DNA is passively adsorbed to said liposome.

6. The composition of claims 1 or 2, wherein said DNA comprises the nucleotide sequence of SEQ ID NO:11.

7. The composition of claims 1 or 2, wherein said DNA encodes a polypeptide having the amino acid sequence selected from the group consisting of SEQ ID NO:12 and an immunologically active fragment thereof.

8. A lipid-formulated vaccine composition comprising DNA encoding a polypeptide selected from the group consisting of (i) Brucella melitensis Invasion Protein B having an amino acid sequence as shown in SEQ ID NO: 12; (ii) a polypeptide having at least 95% sequence identity to (i); and (iii) an immunologically active fragment of (i) or (ii).

9. The composition of claim 8, wherein said DNA comprises the nucleotide sequence of SEQ ID NO:11.

10. The composition of claim 8, wherein said DNA encodes a polypeptide having the amino acid sequence selected from the group consisting of SEQ ID NO:12 and an immunologically active fragment thereof.

11. A method of inducing an enhanced immune response to Brucella infection in an animal, comprising administering to said animal an effective amount of the composition selected from the group consisting of claim 1, claim 2, and claim 8, thereby inducing an enhanced immune response which is characterized in that it is greater in magnitude than an immune response induced by a naked DNA construct encoding the corresponding polypeptide selected from the group consisting of (i), (ii), and (iii).

12. The method of claim 11, wherein said enhanced immune response is characterized by increased antibodies.

13. The method of claim 11, wherein said enhanced immune response is characterized by enhanced T cell priming.

14. The method of claim 11, in which said animal is selected from the group consisting of a mammal, a ruminant, a human, a sheep, a goat, a bison, a buffalo, an elk, a reindeer, and a caribou.

15. A method for the differential diagnosis in an animal of brucellosis and vaccination by an immunogenic nucleic acid composition having DNA encoding a polypeptide selected from the group consisting of (i) Brucella melitensis Invasion Protein B having an amino acid sequence as shown in SEQ ID NO:12; (ii) a polypeptide having at least 95% sequence identity to (i); and (iii) an immunologically active fragment of (i) or (ii), comprising the steps of: (a) detecting the presence or absence of Brucella lipopolysaccharide (LPS) in said animal to ascertain whether or not said animal has a brucellosis infection;(b) detecting the presence or absence of said immunogenic nucleic acid composition in said animal to ascertain whether or not said animal has been vaccinated against brucellosis infection; and(c) correlating the results of steps (a) and (b) to determine whether or not said animal has a brucellosis infection and/or has been vaccinated against brucellosis.

16. A method for determining whether an animal free of brucellosis infection has been vaccinated by an immunogenic nucleic acid composition having DNA encoding a polypeptide selected from the group consisting of (i) Brucella melitensis Invasion Protein B having an amino acid sequence as shown in SEQ ID NO: 12; (ii) a polypeptide having at least 95% sequence identity to (i); and (iii) an immunologically active fragment of (i) or (ii), comprising the steps of: (a) detecting the presence or absence of Brucella lipopolysaccharide (LPS) in said animal to ascertain whether or not said animal has a brucellosis infection;(b) detecting the presence or absence of said immunogenic nucleic acid composition in said animal to ascertain whether or not said animal has been vaccinated against brucellosis infection; and(c) correlating the results of steps (a) and (b) to determine whether or not said animal free of brucellosis infection has been vaccinated with said composition.

17. The method of claims 15 or 16, in which steps (a) and/or (b) are performed on serum obtained from said animal using an ELISA-based assay.

18. A kit comprising: (a) a means for detecting brucellosis infection in an animal; and (b) a means for detecting vaccination of said animal by an immunogenic nucleic acid composition having DNA encoding a polypeptide selected from the group consisting of: (i) Brucella melitensis Invasion Protein B having an amino acid sequence as shown in SEQ ID NO:12; (ii) a polypeptide having at least 95% sequence identity to (i); and (iii) an immunologically active fragment of (i) or (ii).

19. The kit according to claim 18, in which said means are ELISA-based.