Figure 3

REV-specific antibody titers-specific antibody responses detected by indirect ELISA induced from 1 to 4 weeks post the first inoculation, and the booster inoculations were conducted at the second week post first inoculation. A REV-specific antibody titers detected by a commercial REV antibody test kit (IDEXX, Westbrook, USA), serum with titer of higher than 1076 was considered positive for REV antibody. B Gp90-specific antibody responses detected by the gp90 protein-based indirect ELISA, OD_450nm values higher than 0.19 were considered positive for gp90 antibody. Serum samples were collected weekly, and REV-specific and gp90-specific antibodies were detected. The recombinant gp90 protein induced detectable REV-specific and gp90-specific antibodies in chickens at the second week post first inoculation, which was significantly higher (**p < 0.01) than negative control group. And the magnitude of antibody response was time dependent.