TABLE 5.

Cooccurrence of virulence regions among V. cholerae

Serogroup (biotype)	Total no. of strains	No. of strains containing:
		VSP-I	VSP-II	VPI-I	PilE	RTX	RS1	CTXφ	TLC	VPI-2
O1 (classical)	6	0	0	6	6	6	0	6	6	6
O1 (El Tor)	15	10	9	14	15	15	12	13	12	14
O1	2	0	0	1	2	2	0	1	1	1
O139	13	13	13	13	13	13	13	13	13	13a
Non-O1/non-O139	28	1	0	14	28	28	11	11	14	16

^aThese strains only contain the phage-like region of VP1-2; the nan-nag region and restriction modification system are absent. MO2 is an exception, it contains the entire VPI-2.