Attachment of DiI-labeled influenza virus particles to cells at different phases of the cell cycle.

<p>A. H292 cells were transfected with pFucci-S/G2/M Green vector and cultured overnight. GFP expression was observed only in S/G2/M-phase. DiI-labeled virus particles were added to cultured cells and incubated for 15 min at 34°C. Unbound virus was washed off with PBS and the cells were fixed with 4% paraformaldehyde and observed under a Nikon Ti E confocal microscope fitted with a 100× objective lens. The red particles are DiI-labeled viruses. The green colored cells express GFP. B. Cartoon of virus trapping and release on a cell using optical tweezers. Yellow triangle represents optical tweezers; red circle represents virus; light green colored teardrop shape represents the cell. C. Trapping potential was calculated under the indicated conditions. n, refractive index; NA, numerical aperture; T, absolute temperature; blue, red, and green lines represent laser power is at 100 mW, 30 mW, and 10 mW, respectively. D. The cells in the microchip were observed through the objective lens (×100). The DiI-labeled virus is trapped in the chamber of the microchip and transported to the apical membrane of a mitotic cell (arrow 1) but was unable to attach. The same particle was recaptured and then transported to the apical membrane of a G1-phase cell (arrow 2). E. Trace showing virus particle movement after transportation to a dividing (left) or resting (right) cell. White circle (red-cross) in the left panel represents the recaptured virus, whereas that in the right panel represents that the brownian motion of the virus particle on the cell membrane has stopped.