新生水貂肠炎病毒母源抗体消长规律及其亚单位疫苗免疫效果研究

本研究旨在探索水貂肠炎病毒（mink enteritis virus，MEV）的母源抗体消长规律及其亚单位疫苗免疫效果。以免疫母貂所生仔貂为研究对象，采集21、30、45、60日龄仔貂血清，测定水貂病毒性肠炎母源抗体HI效价（MEV HI）；选取25只47~52日龄健康水貂接种制备MEV基因工程亚单位疫苗，免疫前后14 d采血测定MEV HI效价；免疫后14 d进行水貂肠炎病毒攻毒临床症状观察，并测定粪便HA效价；攻毒后14 d对濒死和存活水貂安乐死，采集十二指肠、空肠和回肠进行病理组织学观察和免疫组化检测。结果显示，免疫母貂所产仔貂的MEV HI效价随着日龄的增加逐渐降低，在21日龄时较高，45日龄时少部分仔貂MEV HI效价<1：32，60日龄时大部分仔貂HI效价≤ 1：4；使用制备合格疫苗免疫后14 d对照组水貂的MEV HI效价均不高于1：4，免疫组MEV HI效价升高至1：64~1：512；攻毒保护试验表明，免疫组水貂100%抵抗水貂肠炎病毒强毒的攻击，水貂的精神、饮食、粪便等均未见异常，且攻毒后粪便HA效价为1：8~1：16；病理组织学和免疫组化检测结果表明，MEV基因工程亚单位疫苗能够很好地阻止病毒在肠黏膜上皮细胞的复制和对肠黏膜上皮细胞的损伤。因此，免疫母貂所生仔貂21日龄时体内抗体效价最高，制备的疫苗免疫50日龄左右的水貂时能够突破母源抗体干扰并产生高水平的抗体，能够抵抗水貂肠炎病毒强毒株的攻击。

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.