Construction of a bivalent vaccine against anthrax and smallpox using the attenuated vaccinia virus KVAC103.

BACKGROUND: Anthrax and smallpox are high-risk infectious diseases, and considered as potential agents for bioterrorism. To develop an effective countermeasure for these diseases, we constructed a bivalent vaccine against both anthrax and smallpox by integrating a gene encoding protective antigen (PA) of Bacillus anthracis to the genome of the attenuated vaccinia virus strain, KVAC103. RESULTS: Immunization with this bivalent vaccine induced antibodies against both PA and vaccinia virus in a mouse model. We also observed that the efficacy of this vaccine can be enhanced by combined immunization with immunoadjuvant-expressing KVAC103. Mouse groups co-immunized with PA-expressing KVAC103 and either interleukin-15 (IL-15) or cholera toxin subunit A (CTA1)-expressing KVAC103 showed increased anti-PA IgG titer and survival rate against B. anthracis spore challenge compared to the group immunized with PA-expressing KVAC103 alone. CONCLUSIONS: We demonstrated that the attenuated smallpox vaccine KVAC103 is an available platform for a multivalent vaccine and co-immunization of immunoadjuvants can improve vaccine performance.

Muramyl dipeptide potentiates a Bacillus anthracis poly-γ-d-glutamic acid capsule surrogate that induces maturation and activation of mouse dendritic cells.

Poly-γ-d-glutamic acid (PGA) of anthrax is an important pathogenic factor due to its anti-phagocytic activity. Additionally, PGA has the ability to activate mouse macrophages for the secretion of cytokines through Toll-like receptor (TLR) 2. Peptidoglycan (PGN), a major bacterial cell-wall component, induces inflammatory responses in the host. We assessed whether PGA can induce maturation and cytokine expression in immature mouse dendritic cells (DCs) in the existence of muramyl dipeptide (MDP), the minimum motif of PGN with immunostimulatory activity. Stimulation of immature DCs with PGA or MDP alone augmented expression of costimulatory molecules and MHC class II proteins, which are all cell surface markers indicative of maturation. The observed effects were further enhanced by costimulation of PGA and MDP. PGA alone was sufficient to induce expression of TNF-α, IL-6, MCP-1, and MIP1-α, whereas MDP alone did not under the same conditions. Treatment with MDP enhanced PGA-induced expression of the tested inflammatory mediators; however, the synergistic effect found for PGA and MDP was not observed in TLR2- or nucleotide-binding oligomerization domain (NOD) 2-knockout DCs. Additionally, MDP augmented PGA-induced MAP kinases and NF-κB activation, which is crucial for expression of cytokines. Furthermore, MAP kinase and NF-κB inhibitors attenuated MDP enhancement of PGA-induced cytokine production. In addition, co-culture of splenocytes and PGA/MDP-matured DCs induced higher expression of IL-2 and IFN-γ compared to that of splenocytes and PGA-matured DCs. Collectively, our results suggest that PGA and MDP cooperatively induce inflammatory responses in mouse DCs through TLR2 and NOD2 via MAP kinase and NF-κB pathways, subsequently leading to lymphocyte activation.

Construction of Luminescence- and Fluorescence-Tagged Burkholderia pseudomallei for Pathogen Tracking in a Mouse Model.

Molecular imaging is a powerful method for tracking various infectious disease-causing pathogens in host organisms. Currently, a dual molecular imaging method that can provide temporal and spatial information on infected hosts at the organism, organ, tissue, and cellular levels simultaneously has not been reported for Burkholderia pseudomallei, a high-risk pathogen that causes melioidosis. In this study, we have established an experimental method that provides spatiotemporal information on infected hosts using luminescent and fluorescent dual-labeled B. pseudomallei. Using this method, we visualized B. pseudomallei infection at the organism, organ, and tissue levels in a BALB/c mouse model by detecting its luminescence and fluorescence. The infection of B. pseudomallei at the cellular level was also visualized by its emitted fluorescence in infected macrophage cells. This method could be an extremely useful and applicable tool to study the pathogenesis of B. pseudomallei-related infectious diseases.