Enterotoxic effects of Aeromonas sobria haemolysin in a rat jejunal perfusion system identified by specific neutralization with a monoclonal antibody.

ABSTRACT

Investigations into the pathogenesis of Aeromonas diarrhoea have demonstrated that several different cell-free products of motile aeromonads show enterotoxic activity in suckling mouse, rat, and rabbit assay systems. The relative contributions made by separate cytotoxic and cytotonic activities in the mixture produced by in vitro culture remains unresolved. Using a modified rat jejunal perfusion assay, we have studied the effects of A. sobria culture filtrates containing defined levels of haemolytic and cytotoxic activity and immunoreactivity for anti-cholera toxin. This material induced net water, potassium, and sodium loss with a rapid onset (less than 5 min) that was readily differentiated from the effects of purified cholera toxin (greater than 15 min). In filtrates containing up to 128 haemolytic and cytotoxic units of activity, the enterotoxic activity was neutralized by an anti-haemolysin/cytotoxin monoclonal antibody. No specific histological changes could be found in preparations perfused with enterotoxic material for up to 65 min. These findings indicate that the cytotoxic/haemolytic component of A. sobria culture filtrate is the dominant enterotoxic activity.