TABLE 1.

Comparison of the extent of invasion of A549, J774, and HUVE cells by two strains of A. fumigatus (ATCC 13073 and CHUV) using fluorescence microscopy and a nystatin protection assaya

A. fumigatus strainExtent of invasion of cells by indicated assay
A549J774HUVE
Microscopy (invasion indexb)Nystatin protectionMicroscopy (invasion index)bNystatin protectionMicroscopy (invasion index)d
Invasion indexc% of initial inoculumdInvasion indexc% of initial inoculumc
1307339 ± 1135 ± 72.9 ± 0.591 ± 819 ± 46.0 ± 1.448 ± 5
CHUV30 ± 329 ± 71.3 ± 0.385 ± 1035 ± 46.6 ± 1.550 ± 7
    Beads0NDe0
  • a A549, J774, or HUVE cells were infected with 106 conidia/ml and then analyzed by immunofluorescence microscopy and the nystatin protection assay (A549 and J774 cells only). Polystyrene beads were added to A549 and HUVE cells as a control for nonspecific phagocytosis, and uptake was determined by microscopy. The results are representative of two independent experiments and are expressed as means ± standard deviations of three replicates.

  • b The invasion index determined by microscopy is the number of internalized conidia (green channel − red channel) divided by the number of bound conidia (green channel) per field × 100.

  • c The invasion index determined by the nystatin protection assay is the number of internalized conidia (number of conidia grown in the presence of nystatin) divided by the number of bound conidia (number of conidia grown in the absence of nystatin) × 100.

  • d The percentage of initial inoculum (nystatin protection assay only) is the number of conidia enumerated in the presence of nystatin divided by the initial inoculum × 100.

  • e ND, not determined.