GENETIC-BASIS OF NEISSERIA-GONORRHOEAE LIPOOLIGOSACCHARIDE ANTIGENIC VARIATION

Neisseria gonorrhoeae lipooligosaccharide (LOS) undergoes antigenic va riation at a high rate, and this variation can be monitored by changes in a strain's ability to bind LOS-specific monoclonal antibodies, We report here the cloning and identification of a gene, lsi-2, that can mediate this variation, The DNA sequence of lsi-2 has been determined for N. gonorrhoeae 1291, a strain that expresses a high-molecular-mass LOS, and a derivative of this strain, RS132L, that produces a truncat ed LOS, In the parental strain, lsi-2 contains a string of 12 guanines in the middle of its coding sequence. In cells that had antigenically varied to produce a truncated LOS, the number of guanines in lsi-2 wa s altered, Site-specific deletions were constructed to verify that exp ression of a 3.6-kDa LOS is due to alterations in lsi-2.