Fig 4.

Antibodies directed against endogenous heparan sulfate neutralize infection by C. pneumoniae and C. trachomatis serovar L2. (A) Human HEp-2 cells were stained with single-chain anti-GAG antibodies provided by T. van Kuppevelt. The specificity of each antibody is shown in the table below the panel (34–37, 40–43, 50, 51). Cells were fixed with methanol. The asterisk indicates that this antibody requires an internal 2-O-sulfated iduronic acid residue for binding. CS, chondroitin sulfate; CSC, chondroitin sulfate C; C-6S, chondroitin-6 sulfate; HS, heparan sulfate; GAG, glycosaminoglycan. (B) Neutralization of chlamydial infection by pretreatment of HEp-2 cells with the indicated antibodies. Cells were pretreated with each antibody prior to chlamydial infection (MOI, 10). Infectivity was determined by microscopy 24 (Ctr) or 48 (Cpn) h postinfection. Infectivity following pretreatment with PBS was set to 100%. Cpn, C. pneumoniae; Ctr L2, C. trachomatis serovar L2; Ctr E, C. trachomatis serovar E (n = 4). Statistically significant differences are denoted by ***, **, and *, which indicate P < 0.001, P < 0.01, and P < 0.05, respectively. n.s., not significant. P values state significant changes relative to the corresponding PBS control.