Figure 3. ALV infection activates ERK2 phosphorylation.

DF-1 cells were infected by live viral stocks of ALV-J CHN06 (10⁴ TCID₅₀ 0.2 ml⁻¹), ALV-J NX0101 (10⁴ TCID₅₀ 0.2 ml⁻¹), ALV-A GD13-1 (10⁴ TCID₅₀ 0.2 ml⁻¹), ALV-B CD08 (10⁴ TCID₅₀ 0.2 ml⁻¹) or wild strains of ALV-J KNE131218 (S/P ratio of 1.8) and JX130911A7 (S/P ratio of 2.2). Mock-infected DF-1 cells in various phases were used as a negative control. Cell lysates prepared at the indicated times p.i. were subjected to SDS-PAGE and the amounts of phosphorylated ERK1/2 (p-ERK1/2) and total ERK1/2 were evaluated by western blotting. Chickens solely express the 42-kDa ERK2 isoform. (a) The activation profile of ERK2 was explored in CHN06-infected DF-1 cells. (b) Viral stocks of CHN06 were filtered and pelleted. The filtrate, pellet and supernatant were used individually to infect DF-1 cells for 15 min and 120 h. (c) ERK2 phosphorylation was examined in DF-1 cells infected by ALV-A or B, NX0101 or wild strains of ALV-J, or various virus titers of CHN06, at 15 min or at 120 h p.i. The results are representative of two to three independent experiments.