Plesiomonas shigelloides exports a lethal cytotoxic-enterotoxin (LCE) by membrane vesicles

Abstract

Plesiomonas shigelloides isolated from water in Brazil was previously described as a hemorrhagic heat-labile cytotoxic-enterotoxin producer. We purified this toxin from culture supernatants using ion metallic affinity chromatography (IMAC) followed by molecular exclusion chromatography. The pure toxin presented molecular mass of 50kDa and isoelectric point (pI) around 6.9 by 2D electrophoresis. When injected intravenously, the purified cytotoxic-enterotoxin induced also severe spasms followed by sudden death of mice. Hence, we entitled it as lethal cytotoxic-enterotoxin (LCE). The presence of membrane vesicles (MVs) on cell surfaces of P. shigelloides was observed by scan electron microscopy (SEM). From these MVs the LCE toxin was extracted and confirmed by biological and serological assays. These data suggest that P. shigelloides also exports this cytotoxic-enterotoxin by membrane vesicles, a different mechanism of delivering extra cellular virulence factors, so far not described in this bacterium.

A Comparative Metagenomics Study on Gastrointestinal Microbiota in Amphibious Mudskippers and Other Vertebrate Animals

“…Actually, diverse virulence factors in Aeromonas were recognized in fish diseases [75,76]. Plesiomonas shigelloides in channel catfish and PM was reported to cause subcutaneous hemorrhagic ulcers, as well as kidney and liver necrosis in silver carp [77] (leading to up to a 60% mortality rate) and intestinal diseases in humans [78], as it is a cytotoxic enterotoxin producer [79]. Vibrio vulnificus in BP and golden rabbitfish is pathogenic to tilapia [80], shrimp [81], eels, and humans [82], and it was reported as the most infectious and lethal zoonotic Vibrio .…”