FIG. 3.

Quantitation of secondary inclusions in cells fixed after different time intervals postinfection and at different multiplicities of infection. (A) Chlamydia trachomatis G/UW-57 EBs were inoculated onto McCoy cells at an MOI of 0.5 and allowed to grow for various time intervals prior to fixation and examination for inclusion structure. The horizontal axis represents the hours after infection that cells were fixed with methanol. The vertical axis shows the fraction of total infected cells carrying each inclusion type. The data compare the fraction of infected cells having no IncA-laden fiber (open bars), those that have one or more fibers but no secondary inclusion (dotted bars), those that have an secondary inclusion devoid of chlamydiae (gray bars), and those that have a secondary inclusion containing developmental forms (black bars). Each time point represents analysis from three independent experiments, and the error bars indicate standard deviation. A total of over 1,200 infected cells were evaluated for these data. (B) Examination of secondary inclusion formation at low MOI. Cells were infected with G/UW-57 at the indicated MOI, fixed with methanol 28 hpi, and examined by fluorescence microscopy. All labeling is consistent with that used in panel A. Note that the percentage of filled secondary inclusions does not vary with the reduction in MOI. A total of over 1,000 infected cells were examined for these calculations.