TABLE 3.

Production of cholera toxin by environmental V. cholerae strains and their derivatives (carrying the genome of a genetically marked CTX phage, MSF8.2Φ), and diarrheal response of adult rabbits to these strains

Strain	Cholera toxin production by:		Diarrheal response of adult rabbits by the RITARD model
	GM1-ELISAa	Fluid accumulation in rabbit ileal loops (ml/cm of loops)b	No. of animals challenged	No. responding with fatal diarrheac	No. developing nonfatal diarrhead	Mean duration of shedding of strain in stools (days)
SCE4	UD	0	5	0	0	3.6 ± 1.3
SCE4 (MSF8.2)	2.19 ± 0.61	2.06 ± 0.46	6	0	5	4.8 ± 1.7
SCE188	2.92 ± 0.56	2.27 ± 0.82	5	1	4	4.8 ± 0.8
SCE188 (MSF8.2)	3.96 ± 0.79	2.95 ± 0.78	6	2	4	5.3 ± 1.5
SCE340	UD	0	5	0	0	4.6 ± 1.6
SCE340(MSF8.2)	2.65 ± 0.45	2.09 ± 0.51	4	0	4	6.4 ± 0.8
SCE341	UD	0	5	0	0	3.8 ± 0.8
SCE341 (MSF8.2)	2.71 ± 0.56	2.13 ± 0.64	6	0	5	3.6 ± 1.2
SCE359	UD	0	5	0	4	6.0 ± 1.3
SCE359 (MSF8.2)	2.93 ± 0.51	2.12 ± 0.73	5	2	2	7.2 ± 1.6
SA-317	UD	0	5	0	1	5.6 ± 2.1
P-27459	2.97 ± 0.81	2.55 ± 0.79	6	3	2	6.3 ± 1.6
MO10	3.16 ± 0.73	2.32 ± 0.65	6	4	2	6.1 ± 1.4

^aToxin amounts are expressed in micrograms per unit of optical density of the culture at 600 nm. Values represent the averages of results of five independent observations. UD, undetectable (toxin amounts were less than 0.01 μg/ml, which was the lowest concentration of purified toxin used as control).

^bValues represent the averages of results of five independent observations made in different rabbits.

^cRabbits developing fatal diarrhea died within 12 h after the initiation of diarrhea.

^dThe duration of diarrhea was between 4 and 6 days for rabbits challenged with strains carrying the CTXΦ genome.