Figure 8. NDV infection is pH-dependent and intracellular trafficking involves Rab5a-positive early endosomes.
(A–B) DF1 cells were treated with NH4Cl or Baf A1 for 4 h before or after NDV infection, and cells lysates were prepared for western blot analysis. The NP/b-actin ratio is shown. (C) Intracellular trafficking of NDV requires Rab5a. DF-1 cells were transfected with pEGFP, pEGFP-Rab5wt or pEGFP-Rab5S34N, infected with 5 MOI NDV for 4 h at 37°C and analyzed by western blotting. The NP/b-actin ratio is shown. *P < 0.05. (D) Rab7a function is dispensable for NDV intracellular trafficking. DF-1 cells were transfected with pEGFP, pEGFP-Rab7wt or pEGFP-Rab7T22N, and analyzed using Western blotting as in C. (E) NP co-localized with early endosome marker EEA-1-positive vesicles. DF-1 cells were infected with 5 MOI NDV for 1 h and observed using CLSM: EEA1 (red), NP (green), and cell nucleus (blue). Scale bar = 20 μm.