Therapeutic Effect Of Qin Ling Decoction On Mycoplasma Synoviae Infection In Chickens

Mycoplasma synoviae infection of chicken is caused by Mycoplasma synoviae（MS）and characterized by synovitis and synovitis of tenosynovitis with joint exudation.The pathogens colonize in the respiratory tract for a long time and spread throughput the whole body when the immunity weakens.MS can invade fibroblasts,chondrocytes and blood cells in vitro.The symptoms of sick chicken are joint or foot pad swollen,claudication,respiratory tract disease,body wasting.Later in the course of the disease,due to joint deformation,lying on the ground for a long time and unable to eat,resulting in extreme weight loss,and eventually due to severe failure or other complications of death.At present,chicken farms mainly apply antibiotic to undertake treatment,but abuse of antibiotic can produce drug resistance.The live vaccine cannot protect the infected chicken flocks,and the inactivated vaccine cannot significantly improve the infection.Traditional Chinese medicine for the treatment of mycoplasma sivitis can avoid the development of drug resistance during the treatment,and the Chinese herbal medicine has a wide range of sources,which can also regulate the body’s immunity,so it has a good development prospect.Qin Ling decoction,composed of Scutellaria baicalensis Georgi,Smilax glabra Roxb,Stephania tetrandra S.Moore and Cyathula officinalis Kuan,has the functions of clearing lung dryness and dampness,improving water and swelling,and improving joints.Therefore,this study investigated the therapeutic effect and related mechanism of Qin Ling decoction on MS infection of chicken and provided a new method for clinical treatment of MS infection of chicken.Forty-three 16-week-old broiler breeders with positive serum antibodies to MS were randomly divided into three groups: control group（n=14）,Qin Ling decoction group（n=15）and antibiotic group（n=14）.The control group was not treated;The dosage of Qin Ling decoction group was 4 g/kg.The antibiotic group was treated with Tylosin soluble powder at a dose of 0.2g/kg,once a day for 5 consecutive days,and observed for 20 days.Body temperature,body weight,tarsal joint circumference and tarsal joint index were monitored,and clinical symptoms were scored.The serum antibody levels of TNF-α and MS were detected,and the negative rate of MS serum antibody was calculated.On day 25,the total response rate of each group was calculated according to the percentage decrease of clinical symptom score.Survival rate of each group was calculated.The chickens in each group were examined and scored.Pathological changes were observed.Tracheal viral load was detected in each group.Results: There was no significant difference in each group before treatment.After 25 days of treatment,there were no significant differences in body temperature and tarsal joint circumference between Qin Ling decoction group and control group.Body weight,negative rate of MS antibody,survival rate and total effective rate of Qin Ling decoction group were significantly higher than those of control group.Tarsal joint index,clinical symptom score,autopsy score,tracheal mucosal thickness and tracheal pathogen load were significantly lower than those in the control group.There were fewer tissue fragments in the articular cavity of Qin Ling decoction group.No inflammatory cells and exudate were found in subsynovial tissue.The results showed that 4 g/kg Qin Ling decoction had a good therapeutic effect on MS infection of chicken.Cure rate is 53.3%,total effective rate is 66.7%.In order to explore the mechanism and active components of Qin Ling decoction in the treatment of MS infection of chicken,the adhesion of Baicalin,Astilbin,Ferulic acid,Quercetin and Qin Ling decoction on MS and the relative expression of inflammatory factors in DF-1 cells were detected.The results showed that Qin Ling decoction,Astilbin and Quercetin could significantly reduce the adhesion quantity of MS.Ferulic acid,Baicalin and Quercetin could significantly decrease IL-1β in cell culture supernatant.Qin Ling decoction,Ferulic acid,Baicalin,Astilbin and Quercetin could significantly reduce the m RNA relative expression of IL-6.The m RNA relative expression level of IL-8 was significantly decreased by Baicalin and Astilbin.Baicalin and Quercetin significantly increased the m RNA relative expression of IL-8.Qin Ling decoction,Ferulic acid,Baicalin and Astilbin can significantly decrease the m RNA relative expression of TNF-α,while Quercetin can significantly increase the m RNA relative expression of TNF-α.Astilbin may be the active ingredient of Qin Ling decoction.The results showed that MS infection with DF-1 could promote the expression and release of IL-1β,IL-6,IL-8 and TNF-α.The m RNA relative expression levels of IL-6,IL-8 and TNF-α were significantly decreased by Qin Ling decoction.In conclusion,Qin Ling Decoction has a good therapeutic effect on naturally occurring MS infection of chicken,with a cure rate of 53.3% and a total effective rate of 66.7%.The mechanism of Qin Ling Decoction in treating mycoplasma synovial sac disease may be related to inhibiting the adhesion of MS and the expression of inflammatory factors such as IL-6,IL-8 and TNF-α.The study provides a new method and experimental basis for Chinese medicine treatment of MS infection.