Immunofluorescence analysis of duck plague virus gE protein on DPV-infected ducks

In previous studies, the expression and localization characteristics of duck plague virus (DPV) gE protein have been described in cultured cells, but the properties of DPV gE protein have not been reported in vivo. Immunofluorescence analysis had been used for the detection of virus antigen, but there was no report on the use of this technique for the detection of DPV gE. In this study, we investigated the distribution of DPV gE protein on DPV-infected ducks using polyclonal antibody raised against the recombinant His-gE fusion protein by indirect immunofluorescence assay (IFA).

The recombinant gE protein was highly immunogenicity by ELISA, and the gE was used as an antigen for the preparation of polyclonal antibody, which could be used the first antibody for further experiment to study the distribution of DPV gE protein in DPV-infected tissues by indirect immunofluorescence assay. DPV gE protein were distributed in the immune organs (thymus, bursa of fabricius (BF), Harders glands, spleen), the digestive organs (liver, duodenum, jejunum, ileum), and the other parenchymatous organs (kidney, myocardium, cerebrum, and lung) of DPV-infected ducks, but the positive immunofluorescence signal was not seen in the muscle and pancreas. The lymphocytes, reticulum cells, macrophages, epithelial cells, and hepatocytes served as the principal site for the localization of DPV gE antigen. Moreover, the intensity of fluorescence increased sharply from 12 to 216 h post-infection (p.i.).

In this work, the immunogenicity of the recombinant gE protein was analyzed by ELISA, and we presented the distribution properties of DPV gE antigen in infected ducks for the first time, which may be useful for understanding the pathogenesis of DPV. These properties of the gE protein provided the prerequisite for further functional analysis.