Duck Tembusu virus infection causes testicular atrophy

In recent years, Duck Tembusu virus (DTMUV) is becoming an important emerging and re-emerging pathogen that severely harms the poultry industry in China. The DTMUV disease was principally identified by a sharp decline in egg production, whereas few studies were focused on the virus-reproductive system interaction, especially male reproductive system. Herein, the present study was aimed at investigating the in vivo morphological changes in testis from DTMUV-infected adult Shaoxing ducks. After DTMUV infection, the gross observation indicated that the testis of DTMUV-infected ducks was significantly atrophied at 2 days post-infection (dpi), 4 dpi, and 8 dpi. At microscopic and ultrastructural level, morphological analysis revealed that DTMUV could lead to cytoplasmic vacuolation and exfoliation in seminiferous epithelium, decrease in the diameter of seminiferous tubule (ST), and even induce interstitial inflammation in duck testis. Ulteriorly, the spermatogenic cells, especially spermatocytes, are identified as the target cells of DTMUV infection in the testis of ducks through immunohistochemistry (IHC). And more notably, single virus particles and clustered virus particles were observed in the spermatogenic cells from infected ducks. In summary, our results comprehensively illustrated the effects of DTMUV infection on the testis, the morphological changes underlying testicular atrophy and identified the target cells of DTMUV infection in the testis of ducks.