TABLE 3.
Characteristics of nontoxigenic derivatives of El Tor strains produced by RS1 phage-mediated excision of CTX prophagea
| Parent strain | Presence of genetic region in parent strain |
Presence of genetic region in the nontoxigenic derivative |
Designation of the derivative | ||||||
|---|---|---|---|---|---|---|---|---|---|
| CTX | RS1 | TLC | rtxA | CTX | RS1 | TLC | rtxA | ||
| MG-116926 | + | − | + | + | − | − | − | + | SF2 |
| MG-116226 | + | + | + | + | − | + | + | + | SF3A |
| + | + | + | + | − | − | + | + | SF3B | |
| AR-02214021 | + | + | + | + | − | − | − | + | SF2002 |
| AI-1836 | + | + | + | + | − | − | − | + | SF93 |
| AK-17334 | + | + | + | + | − | − | − | + | SF95 |
| G-7555 | + | + | + | + | − | + | + | + | SF20011 |
| + | + | + | + | − | − | - | + | SF20012 | |
| G-3985 | + | + | + | + | − | − | + | + | SF69-2 |
| P-27457 | + | + | + | + | − | + | + | + | SF20016 |
| + | + | + | + | − | − | + | + | SF20019 | |
a
The presence of different genes was detected using DNA probes and PCR assays. Selected strains were sequenced to confirm deletion events and identify the junctions.