Invasion and fluorescence assay
IECs were grown to confluence on glass coverslips (in 12-well
plates). Each monolayer was overlaid with approximately 120
activated larvae suspended in 0.2 ml of serum-free DMEM
containing 15 mM HEPES and 1.75% agarose [7]. The IECs
were incubated at 37uCin5%CO2 for 1 h. During incubation,
invasion of IECs by T. spiralis infective larvae were observed
continuously under inverted phase contrast microscope (Olympus).
At the end of the experiment, the agarose containing larvae was
removed, and the monolayers were stained with trypan blue. The
area of damaged cells was quantified by NIH image software (ver.
1.57). A total of 25 fields per monolayer were captured by video
microscopy with a 46objective (Olympus).