FIG. 2.

Production of CPAF antibodies in mice inoculated with live, but not mice inoculated with dead, chlamydial organisms. Sera from groups of BALB/c (top panel) and C57BL (bottom) mice inoculated with either live (black bars) or dead (white bars) chlamydial organisms were analyzed for levels of antibodies to chlamydial proteins in an ELISA with the corresponding GST-chlamydia fusion proteins as antigens, as indicated at the bottom of the figure. The results were expressed as mean OD values ± standard deviations. All mouse sera were diluted 1:100. Four to five mice were included in each group. There is a statistically significant difference in levels of antibodies to GST-CPAF between mice inoculated with live and dead organisms in both BALB/c (P < 0.01) and C57BL (P < 0.05) mice. Statistical analysis was done with a two-tailed Student t test (http://faculty.vassar.edu/lowry/tu.html). The lysates made from bacteria expressing GST alone were used as negative antigen controls. None of the serum samples showed any significant binding to the control antigens (data not shown).