The Dynamic of Maternal Antibody Against Enteritis Virus in Newborn Minks and Immune Efficacy of the Subunit Vaccine

The purpose of this study was to investigate the dynamic of mink enteritis virus (MEV) maternal antibody and the immune effects of subunit vaccines.The offspring of immunized female mink were studied,serum of 21,30,45 and 60 days old mink were collected to determine the HI titer of maternal antibody of MEV.25 healthy minks aged 47~52 days were selected to be inoculated with MEV genetic engineering subunit vaccine,and then blood samples were collected 14 d before and after immunization to determine MEV HI titer.The clinical symptoms and the titer of feces HA of mink enteritis virus were observed 14 d after immunization.Dying and surviving minks were euthanized 14 d after challenge,the duodenum,jejunum and ileum were collected for histopathological observation and immunohistochemical detection.The results showed that the MEV HI of the offspring of immunized female mink decreased gradually with the increase of day age,it was higher at 21 d of age,the MEV HI titer of some minks at 45 d was <1:32 and ≤ 1:4 at 60 d.The MEV HI titer of the control mink was not higher than 1:4 on 14 d after the preparation of qualified vaccine,while it was increased to 1:64~1:512 in immune group.Challenge protection tests showed that the immuned minks were 100% resistant to the attack of mink enteritis virus,and there was no abnormality in the mink's mental state,diet and feces,the HA titer of feces matter after challenge was 1:8~1:16.Histopathological and immunohisto-chemical tests showed that MEV genetic engineering subunit vaccine could well prevent the replication of virus in intestinal mucosal epithelial cells and the damage to intestinal epithelial cells.Therefore,the antibody titer was highest at 21 day-old after immunizing female mink,and the prepared vaccine could break through maternal antibody interference and produce high levels of antibodies when it immunized minks at about 50 d of age,and could resist the attack of mink enteritis virus virulent strain.