Infectivity of Chlamydia trachomatis serovar LGV but not E is dependent onhost cell heparan sulfate

The ability of heparan sulfate, heparin, and other glycosaminoglycans to in hibit the infectivity of Chlamydia trachomatis serovars E and LGV was exami ned using a simple competitive inhibition assay with three cell types from the human female reproductive tract, including primary human endosalpingeal cells. With the majority of the glycosaminoglycans tested, LGV was more si gnificantly inhibited than serovar E. We have compared chlamydial infectivi ty between a wild-type Chinese hamster ovary cell line and two glycosaminog lycan-deficient cell lines. LGV was shown to be unable to infect heparan su lfate-deficient and GAG-deficient Chinese hamster ovary cell lines, whereas the E serovar infected these cells as efficiently as the control (nondefic ient) cells. These two sets of experiments confirmed that serovar LGV is mo re dependent on a heparan sulfate-related mechanism of infectivity than is serovar E. This is further supported by the fact that attempts to purify a heparan sulfate-like molecule from either serovar cultured in glycosaminogl ycan-deficient cell lines were nonproductive. Previous reports have suggest ed that chlamydia are able to produce a heparan sulfate-like molecule that is important for attachment and infectivity. We have attempted to detect po ssible binding of a specific heparan sulfate antibody to C. trachomatis by flow cytometry. Results showed no binding of the heparan sulfate antibody t o C. trachomatis serovar LGV or E. Our results strongly indicate that chlam ydiae do not produce a heparan sulfate-like molecule but rather use host ce ll heparan sulfate in order to infect cells.