Study On The Immunoregulation Effect And Clinical Application Of APS On Muscovy Infected With MDRV

Muscovy duck reovirus(MDRV)infection was characterized with white necrosis point in liver and spleen in clinical,it can cause immune suppression and lead to high morbidity and mortality rates which will bring huge economic losses to Muscovy duck breeding industry,however,effective therapeutic for Muscovy duck reovirus infection was still lacked at present.Traditional Chinese medicine polysaccharide had the biological function of antiviral and enhancing immunity with low toxicity and resistance and it showed great potential for the prevention of Muscovy duck reovirus.The astragalus polysaccharide(APS)was selected in this work to study its antiviral and immune test in vitro and in vivo respectively which preliminary revealed the antiviral mechanism.The results showed that astragalus polysaccharides prophylaxis could delay the time that Muscovy duck reovirus clinical symptoms appeared and reduced the pathological changes,significantly reduced mortality,so it may provided certain theoretical basis for the clinical.The main findings were as follows:Experiment 1:The drug concentration screening of APS,HPS,"QL"superfine powder 165 one-day-old Muscovy ducks are randomly divided into 11 groups with 15 in each group which were blank control group,cohabitation infection control group,APS low,medium and high dose preventive group,HPS low,medium and high dose preventive group,"QL" superfine powder low,medium and high dose preventive group.APS and HPS low,medium and high dose preventive group with concentration of 0.1 g/L,0.2 g/L,0.4 g/L were respectively used in water on the first day."QL" superfine powder low,medium and high dose preventive group with concentration of 2.5 g/kg,5 g/kg,10 g/kg were respectively used in water on the first day;The model of cohabitation infection was used for cohabitation infection when 5 days of age and the test period lasted for 25d.The results showed that the mortality of adding Chinese medicine prevention groups' cohabitation infected Muscovy ducks were significantly lower than the control group(mortality rate 53.30%).Around them,mortality rate of APS high dose preventive group was 6.67%,HPS medium doses in prevention group had no death,and mortality rate of "QL" superfine powder medium doses of the prevention group was 13.30%.The time when clinical symptoms appeared of the cohabitation infected Muscovy ducks in cohabitation infection control group clinical symptoms time is 6 days of age,and it was earlier than the cohabitation infected Muscovy ducks in APS high dose preventive group,HPS medium dose preventive group,"QL" superfine powder medium dose preventive group which was 10 days of age,8 days of age,8 days of age respectively.The weight of Muscovy ducks in each preventive group and cohabitation infected control group had no significant difference.The results showed that APS with 0.4 g/L in water drunk by MDRV Muscovy ducks was better in prevention.Experiment 2:To determine medication time and period of treatment of APS 165 one-day-old Muscovy ducks randomly divided into 11 groups with 15 in each group which were blank control group,cohabitation infection control group,three groups which began to use APS atl day age,three groups began to use APS on the cohabitation infection day,three groups which began to use APS when cohabitation infected Muscovy ducks which showed clinical symptoms began to use APS until the end of the experiment.Each time was divided into three kinds of courses,one week,two weeks and the whole period of treatment,0.4 g/L astragalus polysaccharide was added into the drinking water.The results showed that time when clinical symptoms appeared in cohabitation infected Muscovy ducks which began to use APS at 1 day age were later than cohabitation infected Muscovy ducks in the group which began to use APS on the cohabitation infection day and the group which began to use APS when cohabitation infected Muscovy ducks.The mortality rate of cohabitation infected Muscovy ducks in the group which began to use APS for the whole period on 1-day-old was 6.67%,significantly lower than the cohabitation infected Muscovy ducks in cohabitation infection control group(26.67%).The results showed that 1-day-old Muscovy ducks began to use APS for the whole period can delay the time that MDRV infected Muscovy ducks with clinical symptoms,and significantly reduced the mortality of MDRV infected Muscovy ducks.Experiment 3:The influence of the APS on serum cytokines,neurotransmitters and hormones of MDRV infected Muscovy duck one-day-old Muscovy ducks randomly divided into blank control group(BCG),astragalus polysaccharides control group(ACG),cohabitation infected control group(CICG)and astragalus polysaccharides prevention group(APG),three repetitions of each group.The model of cohabitation infection was used for experiment,serum was collected and dissected before cohabitation infection and 3 d,9 d,17 d after cohabitation infection respectively,then measure the content of IL-1,IL-2,4,IL-6,IL-TNF alpha,GC,GH,beta-EP in Muscovy ducks serum with ELISA method.The results showed that:(1)Clinical autopsy results showed that in the early stage of cohabitation infection,APS can delay the time that pathological changes appeared on cohabitation infected Muscovy ducks,in the middle stage of cohabitation infection,APS can reduce pathological changes of Muscovy ducks caused by MDRV?in the late stage of cohabitation infection,the pathological changes of Muscovy ducks which MDRV infected had a tendency to reduce.(2)The Muscovy duck reovirus had no significant effect on IL-1?IL-2_IL-4?IL-6?TNF-a?GC?GH??-EP in the early stage of infection,it effected on the secretion of IL-1,IL,2,IL-6,TNF alpha,inhibited the secretion of IL-4 in the middle stage of the infection,inhibited the secretion of GH in the late stage of infection,promoted the secretion of beta-EP.(3)The content of IL-1,IL-2,IL-4,IL-6,TNF-alpha,GC,GH,beta-EP in Muscovy ducks serum had no significant difference before cohabitation infection and 3 d,9 d5 17 d after cohabitation infection around the blank control group,astragalus polysaccharides control group and astragalus polysaccharides prevent group,it showed that APS had two-way adjustment function on the immune,astragalus polysaccharides could maintained the content of IL-1,IL-2,IL-4,IL-6,TNF-alpha,GC,GH,beta-EP not only in the serum of Muscovy ducks which were infected with MDRV but also in the serum of healthy Muscovy ducks in dynamic equilibrium.Experiment 4:The research on the effect of APS on Muscovy duck reovirus infection in vitro in the range of APS safe concentration,by setting up high,medium,low(1 mg/mL,0.5 mg/mL,0.25 mg/mL)doses of APS and three kinds of dosing way that added APS into CEF ahead of MDRV(chicken embryo fibroblast),added APS and MDRV into CEF at the same time,added APS into CEF after inoculateing MDRV in order to observe the cytopathic effect and then evaluated the effect of APS on Muscovy duck reovirus which infected cells when APS existed in CEF by calculating TCID50 1 mg/mL,0.5 mg/mL,0.25 mg/mL APS were added into CEF brfore MDRV,the TCID50 of MDRV were 10-2.5/0.1mL?10-2.88/0.1mL?10-3.15/0.1mL down from 10-4.12/0.1mL respectively.In the series of concentrations,added APS and MDRV into CEF at the same time and added APS into CEF after inoculateing MDRV had almost no effect on TCID50.The results showed that:in the range of safe concentration,APS inhibited MDRV-YB4 only when adding it into CEF before adding MDRV-YB4 with a certain dose-effect relationship,it suggested that it was better to use APS for prevention in clinical.Experiment 5:The test of clinical application on APS one-day-old Muscovy ducks randomly divided into blank control group(BCG),astragalus polysaccharides group which used APS for two weeks(ACG-2),astragalus polysaccharides group which used APS for three weeks(ACG-3),astragalus polysaccharides group which used APS for six weeks(ACG-6).For the three groups,added 0.4 g/L astragalus polysaccharides in drinking water from the first day,respectively recorded their feeding consumption and death cases every day and weighted at the age of 14,21,28,35,42 days.At the age of 42 days,collecting blood and then separating serum in each group to detect the content of IL-1?IL-2?IL-4?IL-6?TNF-a?GC?GH?p-EP.The results showed that astragalus polysaccharides which used for two weeks,three weeks,six weeks had no obvious effect on feed conversion and body weight,but the survival rate of astragalus polysaccharides group which used APS for three weeks(ACG-3)and astragalus polysaccharides group which used APS for six weeks(ACG-6)was 100.00%,their survival rate improved 2.50%when compared to blank control group(BCG)and astragalus polysaccharides group which used APS for two weeks(ACG-2).At the age of 42 days,the content of IL-1?IL-2?IL-4?IL-6?TNF-??GC?GH??-EP in serum of Muscovy ducks of ACG-2,ACG-3,ACG-6 had no significant difference compared with blank control group,it further verified that using APS could keep the content of IL-1,IL-2,,IL-4,IL-6,TNF-alpha,GC,GH,beta-EP in healthy young Muscovy ducks' serum in dynamic equilibrium.