Primary Study On The Pathogenicity And Membrane Protein Of Mycoplasma Gallisepticum Isolated From Chongqing

Mycoplasma Gallisepticum(MG) infection have also been called Chronic Respiratory Disease (CRD).With the increasing of stress and intensitive rearing,change of rearing method and high rearing density,Mycoplasma Gallisepticum(MG) infection have already been a major problem that affects the poultry industry through its increased morbidity.MG infection can be easily triggered under such environment as poor ventilation,a sudden air temperature change and excessive ammonia and dusts,even after vaccinating the live vaccine such as Newcastle disease,Infectious bronchitis and Infectious Laryngotracheitis can also triggered this disease.Mycoplasma Gallisepticum is spread by aerosol exposure and egg transmission,consequently,it can be exist and spread in flock for a long time.According to the serological investigation and statistics,the average infection rates in flocks were 50%～80%,when catching this disease,the unhealthy chicken rate increased about 10%,egg production of layer dropped 10%～20%,weight lost 38%,the period of onset to market prolonged,feed conversion efficiency reduced 20%.This arouse considerable drug cost,at the same time,it could cause drug-remain in poultry products.A lot of countries have taken importance to preventing this disease for many years.Membrane protein of MG is an important protective antigen.Reports about its antigen ingredient molecular weight were incompletely consistent,until now has not concerned the report about Chongqing local MG pathogenicity and the membrane protein.This research supplied the foundation to the diagnosis,prevention and treatment of CRD with the initial investigation on the pathogenicity,composition and immunogenicity of membrane protein of MG. 1.The pathogenicity analysis of MG isolated from ChongqingObjective To comprehend the pathogenicity of MG isolated from Chongqing.Methods Healthy cockerels aged 20 days were infected with the liquid culture medium of the type strain PG₃₁ and field MG strain isolated from Chongqing that have been transferred 5 times through nose and oral administration ways.After 8 days,10 dosages of IB-H120 were taken as the stimulation infection.The increase heavy and morbidity situations of each group chickens during the entire trial period were record.All trial chickens were dissected to observe the aerocyst damage situations and figure out the scores.Result None clinical symptoms showed by any trial chickens before stimulation infection that showed inapparent infection but emerged bad completely after stimulation infection;Each poisonous group increased extremely remarkable lower than the control group,also MG group isolated from Chongqing extremely remarkable lower than the standard PG₃₁ group; Aerocyst of every poisonous group damaged extremely remarkable higher than the control group(0).Conclusion Inapparent infection showed by chickens infected with MG isolated from Chongqing without any external stimulation,after infection,the chicken increased slowly,the growth and development was blocked seriously,and the aerocyst seriously damaged.2.The extraction of membrane protein of MG isolated from Chongqing and its SDS-PAGE analysisObjective To comprehend the composition and their difference and identity of membrane protein of MG isolated from Chongqing.Methods Membrane protein of MG was extracted by Triton-100 together with low concentration of KI,then analyzed by SDS-PAGE.Result Membrane protein was obtained high production.Membrane protein compositions of three field strains were similar to type strain of PG₃₁ but one had large distinctions showed by SDS-PAGE.Conclusion Triton-100 together with low concentration of KI was a fine way to extract membrane protein of MG and MG infection in Chongqing could be manifold.3.Investigation of immunogenicity of MG isolated from ChongqingObjective To investigate the main antigenic components of type and field strains of MG. Methods Membrane protein of PG₃₁ and field strains of ZY2 and ZY4 were extracted to inoculate chicken to obtain antiserum.Immunogenicity of membrane protein of MG was analyzed by West-blotting.Result The immunogenicity of field strain of ZY2 and PG₃₁ showed high consistency,which showed three specificity bands:100kDa,66kDa,42kDa.Field strain of ZY4 reacted with self antiserum also showed three bands:100kDa,75kDa,42kDa.Two bands showed by reaction with every antiserum were 100kDa and 42kDa.Conclusion membrane protein of MG had immunogenicity and there were some common immunogenic protein among MG strains.