Patent
Certain attenuated mutants of Brucella , especially B. melitensis, B. abortus, B. suis and B. ovis , when administered to a human or animal trigger a protective immune response such that subsequent challenge with virulent Brucella of the same species does not result in disease or results in much less severe symptoms. Functional inactivation of galE, a virB gene or the operon (ORFs 1087-1090) comprising the gene encoding β-hexosaminidase (BMEI1087) and a lytic murein transglycosylase gene (BMEI1088). A specific example of the attenuated galE mutant which produces a protective immune response is B. melitensis GR024. The specific example of an inactivated ORF1087-1090 operon is B. melitensis GR026; it has an insertion mutation in the promoter region upstream of ORF 1090. Vaccination with live cells of either or both of these mutants results in a T cell response which protects the human or animal against challenge with virulent B. melitensis . Similar strategies for protective immunity using live attenuated mutants are useful for B. abortus, B. suis and B. ovis as well.
1. An isolated attenuated strain of Brucella melitensis in which there is a polar insertion mutation or a deletion mutation which functionally inactivates or prevents expression of a gene encoding deoxyguanosinetriphosphate triphosphohydrolase, wherein said gene, prior to inactivation, comprises the complement of the sequence set forth in nucleotides 2138-3346 of SEQ ID NO:27.
2. The isolated attenuated strain of claim 1 , wherein said strain is a Brucella melitensis 16M strain.
3. The isolated attenuated strain of Brucella melitensis of claim 2 , wherein said attenuated mutant is GR026 (ATCC Accession No. PTA-11877) or Brucella melitensis GR01090Δ (ATCC Accession No. PTA-11878).
4. The isolated attenuated strain of claim 1 , wherein said mutant strain expresses a listeriolysin 0 gene from Listeria monocytogenes.
5. An immunogenic composition comprising live cells of at least one isolated attenuated mutant strain of the Brucella melitensis of claim 1 and a pharmaceutically acceptable carrier.
6. The immunogenic composition of claim 5 , wherein said isolated attenuated mutant strain is Brucella melitensis GR026 (ATCC Accession No. PTA-11877) or Brucella melitensis GR01090A (ATCC Accession No. PTA-11878).
7. A method of inducing an immune response against Brucella infection by administering an effective amount of the immunogenic composition of claim 5 .
8. The method of claim 7 wherein said isolated attenuated mutant strain is Brucella melitensis GR 026 (ATCC Accession No. PTA-11877) or Brucella melitensis GR01090Δ (ATCC Accession No. PTA-11878).
9. A method of inducing an immune response against Brucella infection by administering an effective amount of an immunogenic composition comprising cells of at least one isolated attenuated mutant strain of the Brucella melitensis GR026 (ATCC Accession No. PTA-11877) or GR01090Δ (ATCC Accession No. PTA-11878) and a pharmaceutically acceptable carrier.