Attenuated
A mutated Bordetella strain comprising at least a mutated ptx gene, a deleted or mutated dnt gene and a heterologous ampG gene is provided. The attenuated mutated Bordetella strain can be used in an immunogenic composition or a vaccine for the treatment or prevention of a Bordetella infection. Use of the attenuated Bordetella strain for the manufacture of a vaccine or immunogenic composition, as well as methods for protecting mammals against infection by Bordetella are also provided.
1. A method of making a live attenuated Bordetella strain for use in a vaccine, the method comprising the steps of:
providing a live parent Bordetella strain comprising a pertussis toxin gene (ptx), a dermonecrotic toxin gene (dnt) and a Bordetella ampG gene;
mutating the ptx in the live parent Bordetella strain;
deleting or mutating the dnt gene in the live parent Bordetella strain; and
replacing the Bordetella ampG gene in the live parent Bordetella strain with a heterologous ampG gene, wherein the resulting live mutated Bordetella strain is able to colonize the respiratory tract of a subject and induce protective immunity in the subject.
2. The method of claim 1 , wherein the step of replacing the Bordetella ampG gene in the live parent Bordetella strain with the heterologous ampG gene causes the live attenuated Bordetella strain to express less than 5% of the tracheal cytotoxin (TCT) activity compared to the TCT activity expressed by the live parent Bordetella strain.
3. The method of claim 1 , further comprising the step of introducing into the live attenuated Bordatella strain a heterologous expression platform which carries a heterologous antigen.
4. The method of claim 3 , wherein the heterologous antigen is one expressed by a respiratory pathogen selected from the group consisting of: Neisseria, Pneumophila, Yersinia, Pseudomonas, Mycobacteria , and Influenza.