Recombinant gp90 protein expressed in Pichia pastoris induces a protective immune response against reticuloendotheliosis virus in chickens

Reticuloendotheliosis virus (REV) causes an oncogenic, immunosuppressive and runting syndrome in multiple avian hosts worldwide. In this study, the gp90 protein of REV was secretory expressed in Pichia pastoris with high production level and good antigenicity. To fully utilize the expression potential of the P. pastoris expression system, a panel of Pichia clones carrying increasing copies of the gp90 expression cassette was created using an in vitro multimerization approach and the effects of gene dosage on gp90 expression were investigated. Results demonstrated that an increase in gp90 copy number can significantly improve the yields of gp90 protein. Following expression and scale-up, the gp90 protein production level could reach up to 400 mg/L, and the protein could be detected by gp90-specific monoclonal antibody. Investigations of its vaccine efficacy demonstrated that the recombinant gp90 protein was able to induce sustained high levels of antibodies against REV as being detected by ELISA and virus neutralizing test. Furthermore, immunization of chickens with the recombinant gp90 vaccine fully protected the animals from viremia after REV infection. Overall, the yeast-expressed gp90 protein retains good immunogenicity and could be used as a potential subunit vaccine candidate for REV prevention.

► Reticuloendotheliosis virus (REV) gp90 protein was expressed in P. pastoris. ► The increase in gp90 copy number enhanced the yield of gp90 protein. ► The ygp90 induced high levels of neutralizing antibodies against REV in chickens. ► The ygp90 vaccine had long immunity duration for at least 22 weeks. ► The ygp90 vaccine protected chickens from viremia caused by REV infection.