Theoretical and Applied Veterinary Medicine (Dec 2023)
Immune response modulation during the progress of gastric ulcer associated with circovirus infection in farming pigs
Abstract
Gastric ulcer in pigs is a common complication of livestock feeding worldwide. Ulcers lead to reduced feed consumption, decreased daily weight gain, and even sudden death, resulting in certain economic losses. Ulceration in the non-glandular part of a pig's stomach is a disease of complex etiology, where disruptions in feed intake, particle size, nutrient content, infections, and stress play important roles. Ulceration of the non-glandular gastric mucosa occurs in pigs of any age, but the highest level of ulcers is observed in pigs aged 3-6 months. The exact cause of ulcer formation remains unclear. Recently, porcine circovirus type 2 (PCV2) has been considered as one of the potential causative factors of gastric ulcers in pigs. The aim of the study was to investigate molecular markers of gastric epithelium damage and the induction of gastric ulcers under the conditions of PCV2 viral infection. The research was conducted at the Pig Complex and the Research Center for Biosafety and Environmental Control of Agricultural Resources at Dnipro State Agrarian and Economic University "Biosafety-center" (Dnipro city). Histological, immunohistochemical, and PCR studies were carried out on stomach tissue samples with manifestations of ulcers. The results of histological studies revealed several findings in the fundal part of the stomachs. These included erosive gastritis, lymphadenitis, and inflammation in mesenteric lymph nodes. Additionally, pathological-histological signs of recurrent rhomboid-shaped cardiac ulcers were observed. These ulcers had an average size of 5×4.9 cm and a depth of approximately 2/3 of the thickness of the muscular layer. Furthermore, purulent-necrotic fibrinoid detritus was evident at the edges of the ulcers. PCR analysis confirmed the presence of PCV2 infection in all animals with ulcers. At the same time, PCV2 was not detected in the control group. In the stomach tissue of animals with ulcers, a statistically significant decrease in interferon-alpha content (P < 0.05) relative to the control was determined. The decrease in interferon production in damaged areas of the stomach indicates suppression of innate immunity. The obtained results indicate that PCV2 infection, along with weakened immune response, can be an important factor in initiating ulcerative disease and functional disturbances of the intestinal system in pigs.
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