Reduced elevation of [Ca²⁺]i in ΔLB361 mutant-infected macrophages.

<p>(A). Change of [Ca²⁺]i in J774A.1 or THP-1 cells during infection with different leptospires for the indicated times determined by laser confocal microscopy.The intensity of green fluorescence reflects the [Ca²⁺]i in macrophages. The images at “0 h” indicate the [Ca²⁺]i in the J774A.1 and THP-1 cells before infection. EGTA is an extracellular Ca²⁺ chelator to block extracellular Ca²⁺ influx. U73122 is a mammalian cell PI-PLC inhibitor. Neomycin is a blocker of IP₃ production. (B). Statistical summary of [Ca²⁺]i changes in the macrophages during infection with different leptospires. Data from experiments such as shown in A. Bars show the means ± SD of three independent experiments. The values at “0 h” indicate the [Ca²⁺]i in the J774A.1 and THP-1 cells before infection. Five hundred cells were analyzed for each of the samples. *: <i>p</i><0.05 <i>vs</i> the fluorescence intensity reflecting [Ca²⁺]i in the J774A.1 or THP-1 cells before infection (0 h). ^▴: <i>p</i><0.05 <i>vs</i> the fluorescence intensity reflecting [Ca²⁺]i in the EGTA-untreated J774A.1 or THP-1 cells infected with wild-type <i>L. interrogans</i> strain Lai. ^#: <i>p</i><0.05 <i>vs</i> the fluorescence intensity reflecting [Ca²⁺]i in the EGTA-treated J774A.1 or THP-1 cells infected with wild-type <i>L. interrogans</i> strain Lai. The statistically significant differences were determined by ANOVA variance analysis plus Dunnett’s multiple comparison test.