The Repairability And Regulation Of HEP On Intestinal Mucosal Barrier Dysfunction And Immune Suppression In MDRV-infected Muscovy Ducks

It has been a long history to use hericium erinaceus for treatment of digestive system diseases depended on its main active ingredient named as hericium erinaceus polysaccharide(HEP),which has effects of anti-inflammatory,antiulcer,antivirus and immune regulation.The protection and repairability of HEP on intestinal mucosa in virus-infected muscovy ducks has never been reported before.Muscovy duck reovirus(MDRV)could lead to intestinal damage and immune suppression in muscovy ducklings.This reseach was aimed at exploring the effects of HEP on intestinal mucosal structure,mucosa-associated immune cells,percentages and ratios of CD4+,CD8+ T lymphocytes in the peripheral blood of MDRV-infected muscovy ducks,thus elaborating the repairability and regulation of HEP on intestinal mucosal barrier dysfunction and immune suppression,and providing a reference dose of HEP.The methods and results were as follows:1.Determination the optimal dose of HEPBased on the established model of MDRV infection,seventy-five 1-day-old muscovy ducks were randomly divided into five groups:No-treatment control group,Infected control group,High-dose HEP group(0.4 g/L),Mid-dose HEP group(0.2 g/L)and Low-dose HEP group(0.1 g/L).Death cases were recorded everyday,paraffin sec-tions of duodenum were prepared for observation of Intestinal indexes on the twenty-fifth day.The results showed that prolonged incubation period,relieved clinical symptoms and decreased mortality were obtained in HEP groups,especially in Mid-dose HEP group;in addition,V/C values and Villus surface area was significantly decreased in MDRV infection group,and all above indexes increased significantly(P<0.01)in HEP groups(particularly in Mid-dose HEP group)in comparation with MDRV co-infection group.2.Effects of HEP on immune barrier and CD4+,CD8+ T lymphocyte subsets of peripheral blood in MDRV-infected muscovy ducksTwo hundred 1-day-old ducks were randomly divided into four groups:No-treatment control group,HEP control group,Infected control group,HEP prevention control,and MDRV infection was based on the established infection model.Morphology of duodenum,jejunum and ileum(villus height,villus width,V/C values,thickness of intestinal wall and surface area of villus)and numbers of immune cells(intraepithelial lymphocytes,goblet cells,mast cells)in each groups were detected at 0 d,1 d,3 d,6 d,10 d,15 d and 21 d post-habitation infection,respectively,and CD4+,CD8+ T lymphocyte subsets in peripheral blood were tested using flow cytometry.The results were as follows:(1)Compared with blank control,obvious damage of intestinal villi,exfoliated epithelial cells and infiltrated inflammatory cells were observed in MDRV infection group;and-villus height,villus width,villus density,V/C values,surface area of villus,thickness of intestinal wall,as well as numbers of intraepithelial lymphocytes,goblet cells and mast cells were all decreased.Compared with MDRV infection group,a significant(P<0.05)or extremely significant(P<0.01)increase of above indexes,as well as protected intestinal mucosa and less inflammatory cell infiltration were achie-ved in HEP prevention control,and there was a positive correlation between clinical effects and administration time of HEP.(2)Compared with blank control,percentages and ratios of CD4+,CD8+ T lymphocytes in the peripheral blood of MDRV infection group were decreased;com-pared with MDRV infection group,the above indexes of HEP prevention control were increased,especially the CD4+ T lymphocytes and the ratios of CD4+/CD8+ ratios with a extremely significant increase.Conclusions:MDRV could damage intestinal mucosal barrier function and in-duce immune suppression through impairing cellular immunity and humoral immu-nity in MDRV-infected muscovy ducks.Mid-dose of HEP(0.2 g/L)could significan-tly improve structurally intestinal integrity and immunity,thus reducing the mortality of infected ducks.