Attachment and internalization of a Chlamydia trachomatis lymphogranuloma venereum strain by McCoy cells: kinetics of infectivity and effect of lectins and carbohydrates

Abstract

The kinetics of attachment and ingestion of C. trachomatis serotype L1 by monolayers of McCoy [mouse] cells were studied by using a method that discriminated between attachment and uptake. When .apprx. 1% of the McCoy cells was infected, the proteinase K-resistant chlamydial fraction, regarded as ingested chlamydiae, reached a constant value after .apprx. 3 h of incubation at 37.degree. C. Uptake of chlamydiae at 4.degree. C was not demonstrated. The attached and ingested chlamydial fractions were constant over an 8-fold increase in chalamydial inoculum. Chitobiose and chitotriose, the di- and trisaccharides of N-acetyl-D-glucosamine, reduced the association of C. trachomatis serotype L1 with McCoy cells. Higher concentrations of chitobiose also selectively inhibited ingestion of chlamydiae. A corresponding effect of chitobiose was also observed on the number of chlamydial inclusions. Wheat germ agglutinin, specific for N-acetyl-D-glucosamine residues, reduced the association of chlamydiae when incubated at 4.degree. C, but not at 37.degree. C. A small inhibiting effect of concanavalin A on association of chlamydiae, but no effect of the corresponding carbohydrates, indicates a nonspecific effect on chlamydial attachment of this lectin. Evidently, .beta.1 .fwdarw. 4-linked oligomers of N-acetyl-D-glucosamine are important in the specificity of attachment of C. trachomatis to McCoy cells.