The US2 protein is involved in the penetration and cell-to-cell spreading of DEV in vitro

Previous studies have shown that the unique short 2 (US2) protein contributes to the infection of several herpesviruses. However, little is known about whether the US2 protein of duck enteritis virus (DEV) could also contribute to the DEV infection in susceptible cells. This study is aimed at investigating the role of US2 protein in the DEV infection in vitro. The US2 gene was amplified from DEV and cloned into pET32a (+). The expression of recombinant US2 protein was induced in Escherichia coli. After purification, the recombinant US2 protein was immunized into rabbits to generate anti-US2 sera. The immunoreactivity of anti-US2 sera was determined by Western blot and immunofluorescent assays. The US2 protein was detected in the cytoplasm and plasma membrane of DEV-infected duck embryo fibroblast (DEF) cells by immunofluorescent assay using the anti-US2 serum. When DEV infected DEF cells in vitro, pre-treatment with anti-US2 serum did not affect the attachment of virus, but significantly reduced the penetration and cell-to-cell spreading of DEV in DEF cells. Our data suggest that the US2 protein is involved in the penetration and cell-to-cell spreading during the DEV infection of susceptible cells in vitro.