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• C-terminally truncated E protein, prM-E and E proteins were constructed and applied as subunit vaccine candidates. • The constructed proteins could induce specific antibody responses and provide full protection against DTMUV infection. • The truncated E protein was suggested to be able to serve as a practical subunit vaccine candidate. Duck Tembusu virus (DTMUV) is a major pathogen of duck industry in China. In the current study, we generated different constructs containing envelope (E) protein, pre-membrane-envelope (prM-E) protein, and C-terminally truncated E protein of the DTMUV. The constructed proteins could induce specific antibody responses in young ducks. When ducklings were immunized with the constructed proteins, they were 100% protected against DTMUV infection. Furthermore, the fluorescent signal of the truncated E protein was stronger than other constructed proteins, when Bac-to-Bac baculovirus expression system was applied. Our data demonstrated that the truncated E protein used in the current study could be applied as a potential vaccine candidate to control DTMUV infection in young ducks. [ABSTRACT FROM AUTHOR]

• The chimeric VLPs, designated as E-HA2, contains E protein of the DTMUV and HA2 protein of the H3N2 AIV. • The chimeric VLPs E-HA2 could induce specific antibody responses in both mice and ducks. • The chimeric VLPs E-HA2 could provide 100% protection against homologous virus infection. Duck Tembusu virus (DTMUV) has caused enormous economic losses to the poultry industry in China. In the current study, we generated chimeric virus-like particles (VLPs) containing E protein of the DTMUV and HA2 protein of the H3N2 avian influenza virus (AIV). The chimeric VLPs could induce specific antibody responses in both mice (n = 5/group) and ducks (n = 10/group). After immunizing ducklings with the chimeric VLPs, all immunized ducks (n = 10/group) were 100% (10/10) protected against homologous DTMUV strain and virus shedding was not detected on day 5 post-challenge, whereas 60% (6/10) of the ducklings immunized with PBS presented typical symptoms with a virus shedding rate of 90% (9/10). Furthermore, viral loads were significantly decreased in the birds of the chimeric VLPs immunized group, comparing to that of the PBS immunized group. Our data demonstrated that the chimeric VLPs used in the current study could be applied as a potential vaccine candidate to control DTMUV infections in young ducks. [ABSTRACT FROM AUTHOR]

• A novel duck adenovirus (DAdV-4) was isolated in this study. • DAdV-4 extends the genus Aviadenovirus. • DAdV-4 may become a potential threat to the poultry industry. A novel duck adenovirus, isolated from Jinding Ducks(Anas platyrhynchos domestica), was proposed to be duck adenovirus 4 (DAdV-4), extending the genus Aviadenovirus. In this study, we sequenced the central genome part from Iva2 gene to fiber gene of the DAdV-4 that is conserved in all adenovirus genera. Phylogenetic analysis and protease cleavage site analysis verified the classification of DAdV-4 in the genus Aviadenovirus. Nucleotide identity analysis showed low sequence identity between central genome part genes of DAdV-4 with that of other aviadenoviruses. The phylogenetic tree based on the full amino acid sequence of hexon and DNA polymerase showed that the DAdV-4 appeared on a relatively independent branch. Our analysis suggested that DAdV-4 is a distinct type and represents a novel species. Although DAdV-4 has not caused serious disease outbreaks among ducks yet, the virus should be considered as a potential threat to the poultry industry. [ABSTRACT FROM AUTHOR]