A COMPARATIVE-STUDY OF THE PROPERTIES OF VIBRIO-CHOLERAE O139, O1 ANDOTHER NON-O1 STRAINS

Vibrio cholerae O139 organisms isolated from different parts of India and from Bangladesh were characterised with respect to their haemagglu tination (HA) activity, plasmid content, cholera toxin (CT) production , cell surface protein and lipopolysaccharide (LPS) profiles, and anti genic properties. Of 28 V. cholerne O139 isolates tested, 14 (50%) wer e shown to agglutinate chicken erythrocytes; the HA activity was sensi tive to D-mannose 0.1%. In parallel experiments, 12 (92.3%) of 13 V. c holerae O1 (El Tor) and 12 (75%) of 16 non-O1, non-O139 strains agglut inated chicken erythrocytes. Plasmid analysis of 32 O139 isolates show ed that 12 (37.5%) carried one or more plasmids of 35.8-2.6 MDa. Plasm ids were not detected in any of the V. cholerae O1 strains, although p lasmids were demonstrable in 35% of the non-O1, non-O139 strains teste d. V. cholerae O139 isolates showed an ability to produce CT that depe nded on media composition and other cultural conditions. A comparison of envelope and outer-membrane protein profiles between O1 and O139 is olates failed to show any significant differences. LPS analysis of O13 9 isolates revealed that these organisms were devoid of long ''O'' sid e-chain polysaccharides. Some of the non-O1, non-O139 strains also sho wed similar LPS profiles whereas others showed the presence of long re petitive ''O'' side-chain polysaccharides similar to those seen in O1 organisms. An antiserum raised against V. cholerae O1 strain O395 did not show any significant reactivity towards O139 and non-O1, non-O139 strains although it reacted with other O1 strains. Furthermore, the an ti-O1 serum induced marked protection against challenge with an O1 str ain but not with an O139 strain in passive protection experiments. All these results indicate that, despite sharing some common properties w ith V. cholerae O1, the O139 isolates posses certain characteristics t hat make them distinct from their O1 counterparts.