Identification of target cells for Goose parvovirus infection in the immune system organs

Pathological lesions in the immune organs of ducklings following experimental infection with goose parvovirus

Goose parvovirus (GPV) is the etiological agent of Derzsy's disease, with a natural reservoir consisting only of geese and Muscovy ducks. However, the pathological changes in the immune organs of ducklings experimentally infected with GPV remain unknown. In this study, 2-day-old Cherry Valley ducklings were intramuscularly injected with GPV. Immune organs (e.g., thymus, bursa of Fabricius, spleen, Harderian gland, cecal tonsil, bone marrow, and peripheral blood lymphocytes [PBLs]) were collected 1, 3, 5, 7, 10, and 14 days post-infection (dpi). Pathological lesions were assessed by histology and the viral load was concurrently assessed using quantitative real-time polymerase chain reaction. GPV antigen was detected via immunofluorescence staining and immunohistochemistry. No clinical symptoms or death were observed in the infected ducklings from 1 to 14 dpi; however, lesions with different degrees of hemorrhage and hyperemia were observed in the thymus, spleen and Harderian gland. Lymphocyte necrosis was identified in the thymus and spleen. In the immune organs, the highest viral loads were found in the spleen at 7 dpi, followed by the bone marrow, PBLs, and cecal tonsil at 3 dpi, and the bursa, Harderian gland, and thymus at 1 dpi. GPV antigen was primarily expressed in the cecal tonsil, spleen, and Harderian gland at 5 dpi, as well as in the PBLs and bone marrow at 3 dpi. Our findings indicate widespread GPV replication and dissemination in the immune organs of Cherry Valley ducklings.

Antigen distribution of TMUV and GPV are coincident with the expression profiles of CD8α-positive cells and goose IFNγ

Both Tembusu virus (TMUV) and goose parvovirus (GPV) are causative agents of goose disease. However, the host immune response of the goose against these two different categories of virus has not been well documented. Here, we compared the clinical symptoms and pathological characteristics, antigen distribution and intensity, and expression of immune-related genes in TMUV- and GPV- infected goose. The immunohistochemistry analysis demonstrated that GPV was primarily located in the liver, lung, small intestine, and rectum, while TMUV was situated in the liver, brain, spleen, and small intestine. The induction of IFNγ and proinflammatory cytokines is highly associated with the distribution profiles of antigen and CD8α+ molecules. The effector function of CD8 T cells may be accomplished by the secretion of IFNγ together with high expression of proinflammatory cytokines such as IL1 and IL6. Remarkably, significant increases in the transcription of immune genes were observed after infection, which suggested that both GPV and TMUV can effectively induce immune response in goose PMBCs. This study will provide fundamental information for goose molecular immunology in defending against pandemic viruses.