PURIFICATION AND CHARACTERIZATION OF A CHO CELL-ELONGATING TOXIN PRODUCED BY AEROMONAS-HYDROPHILA

A Chinese hamster ovary (CHO) cell-elongating toxin produced by Aeromo nas hydrophila was purified from cell-free supernatant fluids by ammon ium sulfate precipitation and fast protein liquid chromatography. The purified toxin had an isolelectric point (pi) of 3.7 and a molecular w eight of 70 000 in a single band on isoelectric focusing (IEF) gels an d SDS-PAGE gels, respectively. The N-terminal sequence, amino acids 1- 20, and the amino acid content were determined from Western blots of t he 70 kDa band. No homology with any known microbial toxin was found. CHO cell activity was not neutralized by antiserum to cholera toxin (a nti-CT), and the toxin did not react with anti-CT on Western blots. Th e toxin did not increase cyclic AMP, cyclic GMP, or prostaglandin E(2) levels in CHO cells. No cytotoxic activity was observed. Intragastric administration of purified toxin (5x10(4) and 5x10(8) CHO cell units) induced intestinal fluid accumulation in infant mice. These results s uggest that this toxin may be a novel cytotonic toxin distinct from pr eviously described toxins produced by A. hydrophila or A. sobria. (C) 1995 Academic Press Limited