The dynamic distribution of duck Tembusu virus in the spleen of infected shelducks

Background: Duck Tembusu virus (DTMUV) is a novel member of Flavivirus. The isolated and purified DTMUV strain XZ-2012 was used as a strain model, to intramuscularly inject the six-month egg-laying shelducks with the infective dose of 10(4)TCID(50). The dynamic distribution of the virus in spleen at different time post-infection (pi) was studied using RT-PCR, RT-qPCR, ELISA, immunofluorescence and transmission electron microscopy (TEM). Result: The results showed that the virus occurred in the spleen after 2 hpi and lasted up to 18 dpi. The registered viral load increased from 2 hpi to 3 dpi, and then it diminished from 6 dpi to 18 dpi with a slight rise at 12 dpi. From 2 hpi to 6 dpi the DTMUV particles were mostly distributed in the periellipsoidal lymphatic sheath (PELS) of spleen white pulp, few being found in the sheathed capillary. From 9 dpi to 18 dpi, the DTMUV particles were migrating into periarterial lymphatic sheaths (PALS) around the central artery through the red pulp. Under TEM, the virus particles could be observed mostly in lymphocytes and macrophages. Conclusion: It was suggested that DTMUV invaded lymphocytes and macrophages of the spleen at 2 hpi and replicated significantly from 1 dpi to 3 dpi, being eliminated from 9 dpi to 18 dpi. This is the first study on the dynamic distribution of DTMUV from invasion to elimination in duck spleen conducted by molecular and morphological methods. It could provide theoretical basis for the occurrence, development and detoxification of the virus in the organs of the immune system.