Figure 1.

Flow cytometric analysis of the binding of the anti-A capsule specific mAb 95/674 (A) and of mouse anti-ACWY capsule antiserum to meningococcal cells (B). The fluorescence intensity of fixed bacterial cells was determined (counts). Isolate 2602: reference isolate; isolate 1976: no capsule expression in the mutant carrying a non-synonymous SNP in the ctrE gene responsible for translocation of the polysaccharide; isolate 2008: increased capsule expression in the mutant carrying a non-synonymous SNP in the csaB gene that codes for a capsule polymerase; isolate 1666: lack of binding of antibodies to the mutant carrying a stop mutation in the csaC gene that encodes an O-acetyltransferase.