Optimization of virulence functions through glucosylation of Shigella LPS

Shigella, the leading cause of bacillary dysentery, uses a type III secretion system (TTSS) to inject proteins into human cells, leading to bacterial invasion and a vigorous inflammatory response. The bacterium is protected against the response by the O antigen of lipopolysaccharide (LPS) on its surface. We show that bacteriophage-encoded glucosylation of Shigella O antigen, the basis of different serotypes, shortens the LPS molecule by around half. This enhances TTSS function without compromising the protective properties of the LPS. Thus, LPS glucosylation promotes bacterial invasion and evasion of innate immunity, which may have contributed to the emergence of serotype diversity in Shigella.     

Bacterial invasion: the paradigms of enteroinvasive pathogens

Invasive bacteria actively induce their own uptake by phagocytosis in normally nonphagocytic cells and then either establish a protected niche within which they survive and replicate, or disseminate from cell to cell by means of an actin-based motility process. The mechanisms underlying bacterial entry, phagosome maturation, and dissemination reveal common strategies as well as unique tactics evolved by individual species to establish infection.     

Impregnated and covered birch plywood performance during external exposure

We evaluated the performance of covered and impregnated birch plywood (BP) in the outdoor environment. Fungal growth, crack formation, and surface hydrophobicity were regularly assessed over 36 months. After 2 months, uncovered BP was severely colonised by disfiguring fungi. During the test period, the surface of plywood with better coatings (solvent- or water-based) was not overgrown or was overgrown slightly with fungi, no cracks were formed, and the surface hydrophobicity was stable. Similar results were observed for laminates with phenol and melamine film. Plywood impregnated with copper and organic biocides, with retention conforming to Use Class 3 (EN 335:2013), did not protect the plywood from crack formation within several months and the severe growth of disfiguring fungi within a year. The blue stain fungus Aureobasidium pullulans was identified for all overgrown test variants. No rot fungi were detected after a 36-month exposure.