Post-weaning diarrhea caused by F18 and its impact on mucosa-associated microbiota and immune responses in the jejunum of nursery pigs.

This review examines the impacts of F18 () on the mucosa-associated microbiota, mucosal immune responses, oxidative stress, and intestinal morphology in the jejunum of nursery pigs. F18 is a major cause of post-weaning diarrhea (PWD) in nursery pigs, mainly due to the production of enterotoxins that disrupt electrolyte balance in the intestinal lumen, leading to diarrhea, growth retardation, increased mortality, and economic losses. Experimental F18 challenge models have shown an increased incidence of diarrhea (28.3%), along with reductions in average daily gain (24.1%), average daily feed intake (12.5%), and gain-to-feed ratio (14.9%). These adverse effects are largely attributed to microbial dysbiosis and heightened mucosal immune responses in the jejunum. The F18 challenge also increases the abundance of harmful bacteria while reducing beneficial bacteria in the jejunal mucosa. Research using this challenge model has demonstrated elevated levels of tumor necrosis factor-α (14.9%), interleukin-8 (10.9%), immunoglobulin A (9.2%), immunoglobulin G (19.7%), malondialdehyde (50.7%), and protein carbonyls (32.3%). These immune and oxidative responses are associated with reductions in villus height (VH) (10.2%) and VH-to-crypt depth ratio (10.7%), as well as an increase in Ki-67 proliferative cells (35.4%) in the jejunum. In conclusion, F18 induces PWD and compromises intestinal health in nursery pigs through dysbiosis, inflammation, oxidative stress, and morphological changes, ultimately impairing growth.