The comparison of villous damage at different ages of piglets infected with porcine epidemic diarrhea virus

Abstract

An outbreak of porcine epidemic diarrhea (PED) is spreading in Thailand since 2007, leading to the loss of economy to pig farmers. The causative agent of this disease is porcine epidemic diarrhea virus (PEDV). The objective of this study was to investigate gross lesions and histopathology of the small intestine of PEDV-infected piglets of different ages. The three parts of the small intestine: duodenum, jejunum, and ileum, were obtained from 3-day- and 10-day-old piglets infected with PEDV and normal piglets (control) for histopathological study and immunohistochemical staining using antibodies against PEDV. The diagnosis of PEDV infection was confirmed using Antigen Rapid TGE/PED Ag Test kit and reverse transcription polymerase chain reaction (RT-PCR). All PEDV-infected piglets showed positive results, while the normal piglets showed negative results. The immunohistochemistry indicated the presence of viral antigens in the cytoplasm of epithelial cells on the villi of the duodenum, jejunum, and ileum of piglets infected with PEDV of all ages. Moreover, the ratio of villous height (VH) to crypt depth (CD) was observed to decrease in all parts of the small intestine, particularly jejunum of 3-day-old PEDV-infected piglets, compared to that of normal piglets at the same age. A decreased ratio of VH:CD was observed in jejunum and ileum of 10-day-old piglets infected with PEDV. These findings indicated that younger piglets infected with PEDV showed more severe clinical signs, lesions, and villous damage than the older PEDV-infected piglets.