The present disclosure is related to immunomodulatory bacterial minicells and methods of using the minicells.

Bivalent immunogenic compositions against anthrax and plague are disclosed herein. One bivalent immunogenic composition comprises a triple fusion protein containing three antigens, F1 and V from Yersinia pestis and PA antigen from Bacillus anthracis fused in-frame and retaining structural and functional integrity of all three antigens. Another bivalent immunogenic composition comprises bacteriophage nanoparticles arrayed with these three antigens on the capsid surface of the bacteriophage nanoparticles. These bivalent immunogenic compositions are able to elicit robust immune response in a subject administered said the bivalent immunogenic compositions and provide protection to the subject against sequential or simultaneous challenge with both anthrax and plague pathogens.

Disclosed herein are unique adjuvant compositions comprising an attenuated derivative of a bacterial pathogen that undergoes lysis in vivo. In exemplary embodiments, the bacterial pathogen is a Salmonella spp. Also disclosed are methods for enhancing an immune response using the adjuvants disclosed herein.

Disclosed herein are compositions comprising immunomodulatory and oncolytic eubacterial minicells, and the use of the composition in immunomodulatory therapies for cancer. In some embodiments, the minicells are used in combination of immune checkpoint inhibitors in treating cancer.

Heptose-1-monophosphate-7-derivatives are modifiable immunomodulators that can be used to prepare clinically active conjugate compounds. Such conjugate compounds are useful in modulating an immune response in a subject.

Disclosed are methods and compositions related to polypeptides comprising a fusion of the needle tip protein and translocator protein of a type III secretion apparatus (T3SA) from a type III secretion system (T3SS) of a Gram negative bacteria. Disclosed herein are fusion polypeptides comprising a fusion of a needle tip protein, such as, Bsp22, LcrV, BipD, PcrV, CT053, or CT668, or anantigenic fragment thereof; and a translocator protein, such as, BopB, YopB, BipB, PopB, CopB, or CopB2, or anantigenic fragment thereof from a Type III secretion system (T3SS) of a Gram negative bacteria, such as, Bordetella, Burkholderia, Chlamydia, Pseudomonas, Vibrio, or Yersinia.

A vaccine platform using a Yersinia pestis mutant synthesizing an adjuvant form lipid A (monophosphoryl lipid A, MPLA) for the increased biogenesis of bacterial outer membrane vesicles (OMVs). To enhance the immunogenicity of the OMVs, an Asd-based balanced-lethal host-vector system was constructed to oversynthesize the LcrV antigen of Y. pestis, raise the amounts of LcrV enclosed in OMVs by Type II secretion system, and eliminate harmful factors like plasminogen activator (Pla) and murine toxin from the OMVs. Vaccination with OMVs containing MPLA and increased amounts of LcrV with diminished toxicity afforded complete protection in mice against subcutaneous challenge and intranasal challenge and was significantly superior to that resulting from vaccination with LcrV/alhydrogel. Additionally, the Yersinia OMV can be used as a platform to deliver the heterologous antigens of Bacillus anthraces. Vaccination with multiantigenic self-adjuvanting bionanoparticles from Pseudomonas was also successfully tested in connection with Pseudomonas aeruginosa.

The present invention relates to a vaccine suitable for immunisation against influenza, plague or Y. pestis infection said vaccine comprising outer membrane vesicles (OMVs) and the plague vaccine including the V and/or F1 antigens of Y. pestis.

Embodiments of the disclosure provide for unique lipooligosaccharide/lipid A-based mimetics for use as adjuvants. Methods of generating lipooligosaccharide/lipid A-based mimetics are provided that utilize recombinantly engineered bacteria to produce the mimetics, including, for example, addition of one or more particular enzymes such as acyltransferases, deacylases, phosphatases, or glycosyltransferases.

Disclosed are methods and compositions related to polypeptides comprising a fusion of the needle tip protein and translocator protein of a type III secretion apparatus (T3SA) from a type III secretion system (T3SS) of a Gram negative bacteria. Disclosed herein are fusion polypeptides comprising a fusion of a needle tip protein, such as, Bsp22, LcrV, BipD, PcrV, CT053, or CT668, or anantigenic fragment thereof; and a translocator protein, such as, BopB, YopB, BipB, PopB, CopB, or CopB2, or anantigenic fragment thereof from a Type III secretion system (T3SS) of a Gram negative bacteria, such as, Bordetella, Burkholderia, Chlamydia, Pseudomonas, Vibrio, or Yersinia.