Immunogenic compositions containing bacterial outer membrane vesicles

Inventors

Grandi, Guido • Fantappie', Laura • Irene, Carmela

Assignees

Biomvis Srl

Abstract

This invention relates to outer membrane vesicles (OMVs) from Gram-negative bacteria. The vesicles comprise heterologous proteins or immunogenic fragments thereof expressed as lipoproteins in their membrane. The OMVs of the invention are capable of eliciting an immune response to the heterologous protein or to a fragment thereof when administered to a mammal. Other aspects of the invention relate to methods of preparing the OMVs and immunogenic compositions containing the same.

Core Innovation

The document discloses outer membrane vesicles (OMVs) from Gram-negative bacteria as immunogenic vaccine platforms. The OMVs comprise a lipoprotein consisting of a heterologous protein or an immunogenic fragment, where the heterologous protein is carried as an acylated N-terminal cysteine-containing lipoprotein within the OMV. This configuration is described as enabling the OMV to elicit an immune response to the heterologous protein when administered to a mammal.

A core aspect of the approach is fusing the heterologous protein to a lipoprotein leader sequence, so the lipoprotein machinery lipidates the N-terminal cysteine. The document specifies a lipobox sequence of Leu-(Ala/Ser)-(Gly/Ala)-Cys (SEQ ID NO:111) and describes lipidation of the N-terminal cysteine as a driver for incorporation of the heterologous protein into OMVs. The immune responses described include antigen-specific responses with Th1-skewing in mammals.

The document also addresses OMV production and reactogenicity by engineering Gram-negative bacteria to increase vesiculation and to reduce OMV reactogenicity. It describes hypervesiculation/hyperblebbing strategies and specific pathway-related changes associated with ompA, msbB, and pagP and gna33 in the context of Neisseria, together with reductions in TLR4 activation through altered LPS/Lipid A. Engineered OMVs are described as exhibiting reduced TLR4 stimulation while maintaining or improving antigen expression when the heterologous protein is lipidated.

Claims Coverage

The provided independent claim content defines a method of preparing OMVs from a Gram-negative bacterium where the OMV includes a lipidated heterologous-protein lipoprotein and is capable of eliciting an immune response in a mammal. The inventive features center on the leader-sequence lipidation mechanism, the specified lipobox, and the express-and-isolate method structure.

Across the independent claim content, the inventive core is preparing OMVs from Gram-negative bacteria that incorporate a lipoprotein in which a heterologous protein is lipidated via a specified lipobox-containing leader fusion, and that OMVs are capable of eliciting an immune response to that heterologous protein in a mammal.

Stated Advantages

Documented Applications