BINDING OF GALANTHUS-NIVALIS LECTIN TO CHLAMYDIA-TRACHOMATIS AND INHIBITION OF IN-VITRO INFECTION

A glycoprotein present in Chlamydia trachomatis, serotype L(1), elemen tary bodies (EBs) was earlier found to bind the lectin from Galanthus nivalis (GNA). In the present paper we investigate the interaction of GNA with chlamydial EBs and its effect on in vitro infectivity. The bi nding affinity was studied with I-125-GNA lectin. Within 15 min about 80% maximal binding was obtained. The chlamydia-GNA interaction was in hibited by alpha-methylmannoside, causing a decrease of about 50% at 1 mM, Curve fit analyses indicated two types of binding sites for GNA o n the EBs. The affinity to these differed by a factor of 15. The influ ence of the lectin on the ability of C. trachomatis to infect McCoy ce lls was also investigated. There was a GNA-dependent inhibition with a 50% reduction in the number of intracellular inclusions at 0.2 mu M o f the lectin. The findings indicate the presence of terminal mannose s tructures on the chlamydial surface at or in the proximity of the cell -binding domains. Mannose-binding proteins of eukaryotic cells could b e important for the initial uptake of EBs.