FIG. 2.

LPDI- and Opa₅₀-mediated invasion differ in kinetics and serum sensitivity. Infection with N927 (A) or N303 (B) was performed under low-phosphate conditions, and adherence (black lines) and invasion (gray lines) were determined. Adherence and invasion of N927 at 120 min were set as 100%. (C) Adherence (black bars) and invasion (gray bars) of N927 and N303 were analyzed in the absence and presence of 7.5% serum (fetal calf serum) under low-phosphate conditions (HepM). N927 does not bind to Chang cells in RPMI medium (not shown here; see Fig. S2 in the supplemental material), but binding and invasion of N303 are similar in HepM and RPMI. Intracellular bacteria were quantified by gentamicin survival assays.