Regulatory Effect Of Mori Folium And Eucommiae Cortex Oral Solution On Immunosuppression Of Chicken

Infectious bursal disease(IBD)is a highly pathogenic infectious disease caused by Infectious Bursal Disease Virus(IBDV).Two serotypes of IBD,serotype I and serotype II,are currently known.Chicken is the only natural host of serotype I,and it mainly infected with chickens of 3?6 weeks old causing severe immunosuppression and even death.Chickens infected by IBD become extremely weak.IBDV also causes loss of appetite,white dilute and some other clinical symptoms.Atrophic bursa,renal urate deposition,hemorrhage in pectoral and leg muscles can be observed after anatomy.IBDV can cause severe immunosuppression and cause huge economic losses to the chicken industry.Mori Folium and Eucommiae Cortex Oral Solution(MFEC)is made of mulberry leaves and eucommia.It has the effect of cooling blood and promotes the development of immune organs so that it can help to enhance the immunity.In order to study the prevention and treatment of MFEC on IBD,chemical-drug-induced and IBDV-induced immunosuppressive models were respectively established.These models are used to evaluate the regulatory effect of MFEC on immunosuppression and the enhancement of the vaccine B87.Firstly,we established a chicken immunosuppressive model by injection of cyclophos-phamide to study the effect of MFEC on chicken immune function.120 1-day-old chickens were raised to 13 days old and divided into Blank Control group(BC),Vaccine B87 Control group(B87),Cyclophosphamide+Vaccine B87 group(Cy+B87)and MFEC low dose,medium dose and high dose groups which is MFECL(4.8 g/kg)+Cy+B87;MFECM(9.6 g/kg)+Cy+B87;MFECH(19.6 g/kg)+Cy+B87.Chickens in MFECL+Cy+B87,MFECM+Cy+B87,MFECH+Cy+B87 group were feed with MFEC,and others were feed with normal saline for 7 days.At the age of 16 days,chickens in the BC group and the B87 group got intramuscular injection with normal saline,the other chickens got injection with Cy(40 mg/kg),and the immunosuppressive model was established by 3 days.At the age of 19 days,chickens in the BC group was immunized with normal saline,the other chickens were immunized with vaccine B87,and the second immunization was performed 7 days later.35-day-old chickens were dissected to evaluate the regulation of different doses of MFEC on immunosuppression which was caused by Cy injection method such as HE staining of bursal sections,antibody level detection,etc.The results showed that if the chickens were feed MFEC,their bursal index caused by Cy has been decreased,and bursal damage has been improved.MFEC can down-regulate IL-2 and IL-6 mRNA expression in bursal tissues,and improve antibody production level that caused by B87 vaccine.It proved that the dose of 9.6 g/kg in MFEC was the best,which could inhibit the tissue damage caused by Cy and regulate the immune response of the body.Further,to investigate the potential preventive effect of MFEC on IBD,30 SPF chickens were divided into Blank Control group(BC),IBDV Control group(IBDV),MFEC treatment group(MFEC+IBDV).When chickens were at 22 days of age,chickens in the MFEC+IBDV group were feed with MFEC(9.6 g/kg),and the other chickens were feed with normal saline for 7 days.At 25 days of age,chickens in the IBDV group and the MFEC+IBDV group were infected with IBDV through the nose and eyes,and chickens in the BC group were infected with normal saline.We observed each group for incidence,clinical pathology and mortality.The results showed that compared with IBDV group,chickens in the MFEC+IBDV group has 20%lower mortality.Pathological symptoms such as leg muscle hemorrhage,renal urate deposition are also reduced.It means that MFEC has a certain regulatory effect on IBD,but that MFEC use alone has no obviously preventive effect on IBDBased on the result that the prevention and treatment effect of IBD was not good if treated with MFEC only,an animal model of incomplete immunization was established by inoculating SPF chickens with half of the vaccine dose.MFEC was used to prevent IBDV infection on this animal model to study the enhancement of MFEC to vaccine B87.80 SPF chickens were divided into four groups:Blank Control group(BC group),IBDV Control group(IBDV group),Vaccine B87+IBDV group(B87+IBDV group)and vaccine combined with MFEC group(MFEC+B87+IBDV group).Raised to 19 days old,chickens in the B87+IBDV group and the MFEC+B87+IBDV group were immunized with vaccine B87 at a half of normal dose.When they were 22 days old,chickens in the MFEC+B87+IBDV were feed with MFEC(9.6 g/kg)for 7 days.At 25 days of age,all chickens in each group,except the BC group,were infected with IBDV to establish an immunosuppressive model of IBD and culled at 32 days of age.The clinical symptoms were observed during infection.Subsequently,the level of antibody production and biochemical indicators in the serum were detected.The lesions of the bursa and kidney collected from each group of chickens were observed by optical microscopy and HE staining of tissue sections techniques.At the same time,the apoptosis of cells in the bursa was detected.Of course,the changes in IBDV-VP2,IL-6 and IFN-? mRNA expression were observed by Q-PCR.The results show that the combination of MFEC and vaccine B87 can effectively reduce the incidence rate.And level of antibody production in serum was increased.Compared with B87+IBDV group,damage of tissues of chickens in MFEC+B87+IBDV group that was observed by optical microscopy technique was significantly reduced.The expression of apoptotic protein Bax which detected by immunohistochemistry and Western blot decreased,and the expression of protein Bcl-2 raised.The expression of IBDV-VP2,IL-6 and IFN-y mRNA was significantly reduced by MFEC in bursa.All these results above indicate that MFEC can effectively improve the immune effect of B87 vaccine.It can also reduce the invasion and replication of IBDV,improve damage and apoptosis caused by the infection of the virus,and inhibit the inflammation.In summary,MFEC can improve the immunity of body and promote the development of immune organs in case of injection of Cy or IBDV infection,etc.It also has function of regulating the immunosuppression.At the same time,MFEC can enhance the effect of B87 vaccine.So MFEC can be developed as an immunoenhancer.