The present study is focused on investigating the immunoprotective effects of
CpG-ODN/
Poly(I:C) combined with the viral
glycoprotein gp90
protein against reticuloendotheliosis virus (REV)
infection in chickens. REV's gp90 gene was amplified from the REV-infected cells and expressed in Escherichia coli (E.coli). The expressed products, upon purification, were inoculated into 7-day-old chickens with PBS,
CpG-ODN or
Poly(I:C) adjuvant; Two booster inoculations were then conducted, and then each chicken was challenged. The presence of REV-
antibodies in serum was determined weekly after the first vaccination. The
viremia and immunosuppressive effects of REV
infection were also monitored after the challenge. The neutralizing effects of the
antisera were tested in vitro. The results showed that the recombinant gene containing REV gp90 gene was expressed into the
recombinant protein with a size of 51 Kilo Dalton (KD), which could be recognized by a
monoclonal antibody (MAb) against the gp90
protein. The
viremia and immunosuppressive effects of
avian influenza virus (AIV)
vaccine caused by REV challenge in
CpG-ODN group and in
Poly(I:C) group were dramatically decreased. REV antibody with low titers was induced in gp90 group and the inoculated chickens were partly protected. Compared with those in gp90 group, the titers and the positive ratios of REV antibody in CpG+gp90 group were significantly increased, whereas the
viremia and immunosuppressive effects of AIV
vaccine caused by REV
infection were significantly decreased. In the
Poly(I:C) +gp90 group, the
viremia and immunosuppressive effects caused by REV
infection were also dramatically decreased, although REV antibody responses were softly increased. The diluted
antisera from the vaccinated chickens in both groups could completely inhibit the replication of REV in chick fibroblast cells (CEF). Hence, it can be concluded that
CpG-ODN or the
Poly(I:C) adjuvant can enhance the
antiviral effects of the REV
subunit vaccine against REV
infection, which may result from different mechanisms.