Instability of expression of lipooligosaccharides and their epitopes in Neisseria gonorrhoeae.

We assessed variation in the expression of lipooligosaccharide (LOS) components and their epitopes within populations of a strain of Neisseria gonorrhoeae by using the monoclonal antibodies (MAbs) O6B4 and 3F11 and immunoenzymatic, immuno-colloidal gold electron microscopic, and sodium dodecyl sulfate-polyacrylamide gel electrophoretic procedures. Wild-type organisms varied in binding of both MAbs. We used the intensity of immunoenzymatic colony blot color to distinguish four binding variants for each MAb: red (R), pink (P), and colorless (nonreactive [N]) and an N back to R (N-R) revertant. R to P to R and R to N to R variation occurred at frequencies of 0.2% and 0.02%, respectively. The electrophoretic LOS profiles and MAb immunoblot patterns of the R, P, and N-R variants were the same as those of the wild type. LOSs of the N variants, in contrast, were of lower Mr, bound neither 3F11 nor O6B4 MAb, and contained as their major component the 3.6-kilodalton LOS that bears the L8LOS epitope of N. meningitidis. Results of immunoelectron microscopic studies were consistent with LOS binding patterns. Large number of colloidal gold particles were deposited about both R and P variants, distally from R organisms, but proximally from P organisms. N variant organisms, like their LOS, bound neither of the MAbs. N-R variant organisms were like the wild type in that they showed much variation in the amounts of MAb they bound.