Tyagi, Srishti2022-08-252022-08-252022-05https://hdl.handle.net/1813/111448While engineered Escherichia coli outer membrane vesicles expressing glycans have been previously characterized as efficient vaccine delivery platforms capable of producing a glycan-specific immune response, the mechanisms behind this immune response are largely unknown. Furthermore, the modification of the native structure of lipid A on the OMVs from a hexa- to a penta-acylated form has been routinely used to decrease the toxicity of OMVs under the assumption that it does not have an effect on the adaptive immune response to the antigen displayed on the OMV. Here, we immunized C57BL/6 and T-cell deficient mice with hexa- and penta-acylated OMVs expressing polysialic acid (polySia), a repeating glyco-polymer of sialic acid. Results demonstrate that the immune response to penta-acylated polySia-OMVs relies on the presence of T cells, is driven by B2 cells in the peritoneal cavity, and fails to activate or create a polySia-specific memory B cell response. Alternatively, the response to hexa-acylated polySia-OMVs has a T-independent component that is driven by B1 cells in the spleen and peritoneal cavity, and generates a class-switched, polySia-specific memory B cell population. These results raise key insights for the use of glycosylated outer membrane vesicles (glycOMVs) in vaccination, as considering induction of a T-dependent or T-independent immune response may be beneficial for patients with differing immune competencies.en-USBiological sciences honors programouter membrane vesiclesT cellsimmunologydissertation or thesis