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Abstract

The present invention discloses new live attenuated strains for oral immunization against cholera that are provided in freeze dried formulations for long term storage and administration to humans. These strains combine the two most important properties of live attenuated cholera vaccine candidates. One such property is being well tolerated by people ingesting them. This was achieved by virtue of mutations already described in the art. The second property is having enhanced environmental safety due to the absence of VGJΦ DNA in their genomes and also due to null mutations in the mshA gene or other spontaneous mutations conducive to the lack of MSHA type IV fimbria on the bacterial surface. This was done envisioning that VGJΦ is a filamentous phage able to recombine with CTXΦ and disseminate the cholera toxin genes. This VGJΦ phage as well as the VGJΦ-CTXΦ recombinants uses the MSHA fibers as receptor. Being devoid of MSHA fimbria the vaccine candidates are protected from acquiring CTXΦ from the recombinant hybrid VGJΦ-CTXΦ. Being devoid of VGJΦ, the vaccine candidates are impaired in the dissemination of CTXΦ, via VGJΦ.

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First Claim