Origin, Evolution, and Virulence of Porcine Deltacoronaviruses in the United States

Ma, Yuanmei; Zhang, Yu; Liang, Xueya; Lou, Fangfei; Oglesbee, Michael; Krakowka, Steven; Li, Jianrong

Immunohistochemical staining. Five-micron sections of paraffinembedded tissues were placed onto positively charged slides. After deparaffinization, sections were incubated with target retrieval solution (Dako, Carpinteria, CA) for antigen retrieval. After blocking, a primary anti-PdCV serum antibody from PdCV-infected convalescent sows was incubated for 30 min at 22°C, followed by incubation with a biotinylated horse anti-pig IgG secondary antibody (Vector Laboratories, Burlingame, CA). Slides were further incubated with the ABC Elite complex to probe biotin (Vector Laboratories) and then developed using a 3,3=diaminobenzidine (DAB) chromogen kit (Dako); hematoxylin was used as a counterstain. Tissue sections from PdCV-infected and uninfected samples were used as positive and negative controls, respectively. Tissue sections from PdCV-infected and uninfected samples were incubated with hyperimmune serum against PEDV in the immunohistochemical staining (IHC) assay. Reciprocally, IHC assays were also performed using intestinal tissue sections from PEDV-infected samples using anti-PdCV serum antibody.