Current baculovirus expression systems typically produce soluble proteins that accumulate within the infected insect cell or are secreted into the growth medium. A system has now been developed for the incorporation of foreign proteins, along with the matrix protein, polyhedrin, into baculovirus occlusion bodies. Initial studies showed that a recombinant virus expressing a translational fusion between polyhedrin and GFP did not form occlusion bodies. However, a baculovirus coexpressing native polyhedrin and the polyhedrin-GFP fusion protein formed occlusion bodies that fluoresced under UV light, demonstrating that they included the polyhedrin-GFP fusion protein. This was confirmed by immunoblot analysis. Thus, incorporation of a foreign protein into occlusion bodies depends on an interaction between native polyhedrin and the polyhedrin fusion protein. Electron microscopy demonstrated that the occlusion bodies containing GFP also incorporated virions as expected. These ColorPol occlusion bodies were as infectious to insect larvae as occlusion bodies produced by wild-type virus. This new system expands the capabilities for foreign gene expression by baculoviruses, which has implications for biopesticide design, novel vaccine delivery systems, and fusion protein purification applications.
The aim of this study was to demonstrate the anti-inflammatory effect of Lactobacillus kefirgranum PRCC-1301-derived extracellular vesicles (PRCC-1301 EVs) on intestinal inflammation and intestinal barrier function. Human intestinal epithelial cells (IECs) Caco-2 were treated with PRCC-1301 EVs and then stimulated with dextran sulfate sodium (DSS). Real-time RT-PCR revealed that PRCC-1301 EVs inhibited the expression of pro-inflammatory cytokines in Caco-2 cells. PRCC-1301 EVs enhanced intestinal barrier function by maintaining intestinal cell integrity and the tight junction. Loss of Zo-1, claudin-1, and occludin in Caco-2 cells and the colitis tissues was recovered after PRCC-1301 EVs treatment, as evidenced by immunofluorescence analysis. Acute murine colitis was induced using 4% DSS and chronic colitis was generated in piroxicam-treated IL-10-/- mice. PRCC-1301 EVs attenuated body weight loss, colon shortening, and histological damage in acute and chronic colitis models in mice. Immunohistochemistry revealed that phosphorylated NF-κB p65 and IκBα were reduced in the colon tissue sections treated with PRCC-1301 EVs. Our results suggest that PRCC-1301 EVs may have an anti-inflammatory effect on colitis by inhibiting the NF-κB pathway and improving intestinal barrier function.
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