Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12977-018-0427-0/MediaObjects/12977_2018_427_Fig1_HTML.png)
Co-infection of ALV-J and REV promoted viral replication in CEFs. a REV increased the ALV-J RNA level at 48 hpi and 72 hpi while the ALV-J RNA levels in the co-infection group were decreased compared to those in the singly infected ALV-J at 96 hpi, 122 hpi and 144 hpi. The data represent the mean ± SEM determined from three independent experiments (n = 3), with each experiment containing three technical replicates. Compared with the single-infection group: **P < 0.01. b ALV-J increased the REV RNA level at 48, 72, 96, 122 and 144 hpi. The data represent the mean ± SEM determined from three independent experiments (n = 3), with each experiment containing three technical replicates. Compared with the single-infection group: **P < 0.01. c ALV-J synergized with REV to promote viral protein levels in CEF cells at 48 hpi detected by western blot with an anti-ALV-J gp85 antibody and anti-REV env antibody. d ALV-J synergized with REV to promote viral protein levels in CEF cells at 72 hpi detected by western blot with an anti-ALV-J gp85 antibody and anti-REV env antibody. e ALV-J synergized with REV to promote viral protein levels in CEF cells at 96 hpi detected by western blot with an anti-ALV-J gp85 antibody and anti-REV env antibody