2 STRAINS OF VIBRIO-CHOLERAE NON-O1 POSSESSING SOMATIC (O) ANTIGEN FACTORS IN COMMON WITH V. CHOLERAE SEROGROUP O139 SYNONYM BENGAL

Two strains (O22 reference strain, 169-68, and strain 490-93 isolated from a patient with diarrhea in Thailand) of Vibrio cholerae non-O1 po ssessing somatic (O) antigen factors in common with V. cholerae O139 s ynonym ''Bengal'' are described. The O antigens of these two strains w ere closely related to that of V. cholerae O139 in an a,b-a,c type of relationship, but were not completely identical with serogroup O139. T herefore, both these strains are not classified into the O139 serogrou p of V.: cholerae, because they have their own major antigens. As the strain 490-93 could not be placed into any of the 154 established O se rogroups of V. cholerae, this strain was assigned to a new serogroup, O155. For practical use, the diagnostic antiserum prepared against the O139 reference strain (MO45, ATCC 51394) of V. cholerae must be absor bed with reference strains 169-68 and 490-93 representing serogroups O 22 and O155 of V. cholerae to remove cross-reacting agglutinins of the O22 and O155 strains, respectively.