| Research Abstract |
Vibrio cholerae strains other than serovar O1 (non-O1 V.cholerae) have been known to cause diarrhea. Gastroenteritis associated with V.cholerae non-O1 shows vareous clinical symptomes, such as mucous and bloody diarrhea, vomiting, nausea, fever, abdominal pain as well as watery diarrhea similar to cholera due to V.cholerae O1. Novel serogroup V.cholerae O139 have caused epidemics in India or Bangladesh since 1992. Severe clinical sympotme due to O139 were undistinguishable from cholerae due to V.cholerae O1. These various symptomes may be explained by the production of a varaiety of toxins by V.cholerae non-O1, including cholera toxin (CT) -like toxin, thermostable direct hemolysin (TDH) -like toxin (NAG-rTDH), heat-stable (ST) -like toxin (NAG-ST), El Tor hemolysin-like toxin, and hemagglutinin/protease (Vc-HA/P). We already purified toxins and analyzed biological activity of each toxins. As multiple virulence factors are seemed to affect each other in vivo actually, we analyzed stimulating action of multiple pathogenic factors as well as identification of virulence factors produced by O139.
The results we have got in this periods are (1) we showed unstability of ctchi gene in chromosomal gene of O139 by using restriction fragment pattem, (2) we purified protease produced by O139 and compared to protease of V.cholerae O1, showing both proteases are undistinguishable, (3) Protease treatment of rabbit ileal loop before challenge of E1 Tor-hemolysin-like toxin showed increased fluid accumulation activity because E1 Tor hemolysin-like toxin is known to be processed by protease produced by V.cholerae non-O1 and results in increasing of activity, (4) we observed stimulating action between ct-like enterotoxinand NAG-ST,NAG-ST and E1 Tor hemolysin-like toxin in suckling mouse assay.
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