Deletion mutants of cholera vaccines expressing heterologous antigens
AssigneePresident and Fellows of Harvard College
InventorJohn J. Mekalanos
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Abstract
The invention features a nontoxigenic genetically stable mutant strain of V. cholerae which lacks any functional attRS1 sequences is useful as a live, oral vaccine for inducing immunological protection against cholera and a method for making same. The invention also features a killed, oral cholera vaccine comprising at least a first and a second V. cholerae strain, wherein at least one of the strains is a different serotype, and the vaccine also contains cholera toxin B subunit, produced by at least one of the serotypes.
Claims44
A nontoxinogenic genetically stable mutant strain of Vibrio cholerae, said mutant strain comprising a genetically engineered deletion of DNA encoding a CtxA subunit such that said mutant strain lacks a reactogenic subunit A of cholera toxin, said mutant strain further comprising deletions at attRS1 sequences, said strain further having at least 1000-fold lower attRS1 mediated recombination relative to a parent strain lacking deletions of attRS1, and said mutant strain further comprising DNA encoding an expressed heterologous antigen.
A method of making a genetically stable mutant strain of Vibrio cholerae comprising a deletion of DNA encoding the ctxA subunit such that said mutant strain lacks a reactogenic subunit A of cholera toxin, and said mutant strain further comprising a deletion of attRS1 sequences, and having at least 1000-fold lower attRS1 mediated recombination than a parent strain having at least two copies of attRS1, and said mutant strain further comprising a heterologous antigen, said method comprising:
- introducing into a wild type Vibrio cholerae a plasmid comprising a fragment of Vibrio cholerae DNA which is mutated in its ctxA and attRS1 sequences, said DNA being capable of recombining with wild type Vibrio cholerae DNA inside said wild type Vibrio cholerae resulting in the generation of said mutant strain, and said method further comprising introducing into the wild type Vibrio cholerae a DNA encoding a heterologous antigen.
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