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Protection against duck hepatitis a virus type 1 conferred by a recombinant avian adeno-associated virus

Wang, A P, Liu, L, Gu, L L, Guo, C M, Wu, S, Feng, Q, Xia, W L, Wu, Z, Zhu, S Y
Poultry science 2019 v.98 no.1 pp. 112-118
Avian dependoparvovirus 1, Baculoviridae, Duck hepatitis A virus, Western blotting, blood serum, capsid, duck virus hepatitis, ducklings, electron microscopy, enzyme-linked immunosorbent assay, fluorescent antibody technique, gene therapy, genetic vectors, humans, immune response, immunogenicity, liver, mixed infection, neutralization tests, poultry diseases, quantitative polymerase chain reaction, reverse transcriptase polymerase chain reaction, structural genes, vaccines, viruses
The avian adeno-associated virus (AAAV) has been proved to be an efficient gene transfer vector for human gene therapy and vaccine research. In this experiment, an AAAV-based vaccine was evaluated for the development of a vaccine against duck hepatitis a virus type 1 (DHAV-1). The major capsid VP1 gene was amplified and subcloned into pFBGFP containing the inverted terminal repeats of AAAV, and then the recombinant baculovirus rBac-VP1 was generated. The recombinant AAAV expressing the VP1 protein (rAAAV-VP1) was produced by co-infecting Sf9 cells with rBac-VP1 and the other 2 baculoviruses containing AAAV functional genes and structural genes respectively, and confirmed by electron microscopy, Western blotting and immunofluorescence assays. Quantitative real-time PCR revealed that the titer of rAAAV-VP1 was about 9 × 10¹² VG/mL. Immunogenicity was studied in ducklings. One day ducklings were injected intramuscularly once with rAAAV-VP1. Serum from rAAAV-VP1-vaccinated ducklings showed a systemic immune response evidenced by VP1-specific enzyme-linked immunosorbent assay and virus neutralization test. Furthermore, all ducklings inoculated with rAAAV-VP1 were protected against DHAV-1 challenge. The data of quantitative real-time RT-PCR from livers of challenged ducklings also showed that the level of virus copies in rAAAV-VP1 group was significantly lower than that of the PBS group. Collectively, these results demonstrate that the AAAV-based vaccine is a potential vaccine candidate for the control of duck viral hepatitis.