FIG 3.

BbVRF1 secretes VRF1 into the host cells. (A) Live-cell fluorescence imaging of a coculture of IOZCAS-Ha-I cells (H. armigera cell line) and B. bassiana. Here, 1 × PBS and conidia of WT and BbVRF1 were added to IOZCAS-Ha-I cells, incubated for 72 h, and then observed via differential interference contrast (DIC) microscopy and excitation of EGFP and mCherry. Mock, coculture of 1 × PBS and cells. NC, negative control, coculture of Bb-EGFP (B. bassiana strain transformed with the empty pPK2-Bar-EGFP). BbVRF1, a B. bassiana strain transformant integrated with VRF1 tailed by the fluorescent tag mCherry. Scale bar = 20 μm. (B) Infected IOZCAS-Ha-I cells were detected after incubation with 1 × PBS and conidia of NC and BbVRF1 for 72 h. Main views of different groups are shown and the number of encapsulations was counted. Scale bar = 50 μm. Error bars represent the means ± SD from three replicates. Differences between treatments were compared by one-way ANOVA followed by Tukey’s test for multiple comparisons (***, P ≤ 0.001).