HEPARIN PROTECTS OPA(-GONORRHOEAE FROM THE BACTERICIDAL ACTION OF NORMAL HUMAN SERUM() NEISSERIA)

The pathobiological significance of lipooligosaccharide (LOS) and oute r membrane opacity protein (Opa) changes in gonorrheal disease are poo rly understood. We assessed variants of strain MS11mk with different L OS and Opa phenotypes for their liability to killing by normal human s era. LOS differences correlated with strikingly disparate susceptibili ties to serum killing; LOSa variants were serum resistant, LOSb varian ts were serum sensitive, and sialylation of LOSb variants enhanced the ir survival (as reported previously). Opa phenotype had little influen ce on the killing of serum-sensitive LOSb cells that were incubated di rectly in normal human sera, but preincubation of Opa(+) LOSb variants in heparin increased their serum resistance whereas Opa(-) LOSb varia nts showed no change. Some Opa proteins conferred slightly higher resi stance than others, but heparin preincubation increased serum resistan ce for variants expressing each of seven Opa proteins. These in vitro phenomena may relate to conditions within the male urethra where sulfa te-containing proteoglycans are abundant and where antibody and comple ment may transude from blood plasma. The results suggest that the sele ctive advantage for Opa(+) Neisseria gonorrhoeae bacteria observed in vivo may reflect their ability to utilize host cell components to resi st kilting by host defenses.