Caulobacteria Crescentus bacterial strain for the production of outer membrane vesicles and its use as a vehicle and adjuvant

Abstract

This invention presents the CVOM-2 Gram-negative bacterial strain of Caulobacter crescentus, which has a point mutation in the ompA2 gene resulting in the substitution of arginine 351 for alanine, and a null mutation in the rsaA gene that produces outer membrane vesicles (EMVs) with greater efficiency, quantified as the amount of protein / ml of original culture. These EMVs produce a lower inflammatory response than similar preparations obtained from wild-type Escherichia coli cells or cells modified to reduce this response, or even than preparations obtained from a Caulobacter crescentus strain with a wild-type cell envelope.Genetic methods are also presented that allow the modification of these membrane-bound extracellular matrices (MBs), resulting in the presence of a heterologous protein or antigen in soluble form within the vesicle lumen or associated with the vesicle membrane as part of an integral membrane protein. The antigen may be exposed to the lumen or the vesicle surface, or anchored to the outer membrane via lipids. These MBs induce the generation of antibodies against a heterologous protein present within them. MBs also have an adjuvant effect, inducing antibody generation in response to antigen concentrations that would not otherwise elicit this response.