Efficacy of Cell Wall‐Deficient Spheroplasts Against Experimental Murine Listeriosis

Abstract

Various strategies adapted to develop an efficient vaccine against foodborne pathogen, Listeria monocytogenes, have met with little success. Spheroplasts (bacterial cell devoid of cell wall) are likely to undergo membrane-membrane fusion, leading to the delivery of their content to the cytosol of antigenpresenting cells, thus facilitating MHC class I antigen processing and presentation. In this study, we evaluated the prophylactic potential of Listeria spheroplast-based vaccine against experimental murine listeriosis in comparison with heat-killed Listeria (HKL) and archaeosome-entrapped Listeria whole-cell protein (LWCP). Compared with HKL, the spheroplast-based vaccine was found to evoke better Th1 response as exhibited by the presence of type 1 cytokines in the host (interferon-c and IL-12) and a high IgG 2a /IgG 1 ratio. Robust lymphoproliferative efficacy was apparent in both spheroplast-immunized and archaeosome-entrapped LWCP-immunized groups. The upregulation of costimulatory and effector memory markers upon immunization with spheroplasts was found to be at par with that evoked by archaeosome-entrapped LWCP-immunized group. Central memory response in gated CD8 + T cell was much higher in spheroplastimmunized animals when compared with archaeosome-entrapped LWCP group. The data presented here clearly demonstrate that spheroplasts evoked a robust immune response and offer better prophylactic potential against L. monocytogenes.

New Routes and Opportunities for Modular Construction of Particulate Vaccines: Stick, Click, and Glue

“…In the future, Tag/Catcher display may facilitate comparison between other non-protein vaccination platforms. Such platforms are beyond our scope to cover in detail, but include emulsions, inorganic NPs, immune-stimulating complexes, and lipid-based NPs (e.g., liposomes and spheroplasts) ( 4 , 110 , 111 ).…”

Listeria Monocytogenes: A Model Pathogen Continues to Refine Our Knowledge of the CD8 T Cell Response

“…Therefore, although phagocytic cells can present non-secreted antigens to CD8 T cells to prime them, CD8 T cells specific for non-secreted antigens do not recognize infected non-phagocytic cells and are unable to control listeriosis [ 135 ]. As maternal Lm infection can cause serious fetal or neonatal complications, developing prophylactic and therapeutic vaccines against listeriosis is an ongoing interest [ 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 ]. When designing CD8 T cell-based vaccines against listeriosis, it is important to keep it in mind that non-secreted antigens may not be relevant targets.…”