F 580-A, TL2/CL of influenza A taken with the 580 nm emission filter; F 580-H5, TL1/CL of H5 taken with the 580 nm emission filter; F 650-A, TL2/CL of influenza A taken with the 650 nm emission filter; F 650-H5, TL1/CL of H5 taken with the 650 nm emission filter. *, P < 0.05; **, P < 0.01; ***, P < 0.001.