| Mycoplasma synoviae(MS)is a pathogen causing respiratory diseases and synoviae in poultry.It occurs mainly in chickens,turkeys,ducks,geese,and parrots,and pheasants and quails may also be susceptible.The vertical transmission of Mycoplasma gallisepticum through breeding eggs will result in decreased hatchability and survival rate of chickens,and decreased egg production after infection of adult chickens.Once infected,it is difficult to cure the disease,which has caused huge economic losses to China and even the global poultry industry in recent years.In this study,the pathological model of M.synoviae was established by artificial infection,and the tissue samples of chickens infected with M.synoviae were sequenced by transcriptional sequencing technology.The aim of the study was to explore the differentially expressed genes and related important metabolic network pathways of host chicken in the pathogenesis of M.synoviae infection in order to lay the foundation for further research on the pathogenic mechanism of M.synoviae.The main results are as follows:1.In this experiment,ELISA was used to detect the serum antibody of M.synoviae from 1289 chicken serum samples collected from 5 large-scale farms in Shizuishan,Yinchuan,Wuzhong,Zhongwei and Guyuan of Ningxia.The results showed that the number of M.synoviae positive serum in 1289 serum samples was 866,and the positive rate was 67.1 8%.The positive rate of M.synoviae was 89.67%in Yinchuan,81.29%,69.85%and 60.87%in Guyuan,Shizuishan and wuzhong.The lowest rate was 46.23%in zhongwei.The positive rate of serum antibody of laying hens showed an increasing trend with the increase of age.The positive rate of serum antibody of 12-month-old laying hens reached 100%,and that of 2-month-old chickens was at least 28.35%.The positive rates of MS in 3-month-old,4-month-old,6-month-old,8-month-old and 10-month-old chickens were 42.16%,53.54%,63.78%,82.43%and 85.53%,respectively.Laying hens,broilers and breeding chickens can be infected with M.synoviae,and the serum antibody positive rate of breeding chickens is 90.26%at the highest,64.86%of laying hens,and 55.50%of broilers at the lowest.Chickens in spring and autumn had different degrees of M.synoviae infection,and the infection rate in spring(72.22%)was higher than that in autumn(62.50%).2.In this experiment,the pathological model of M.synoviae was established by using the isolated strains of M.synoviae preserved in the laboratory.Before the establishment of the pathological model of M.synoviae,all the chickens tested negative for serum antibody by ELISA kit.Twenty-six chickens were randomly divided into two groups:blank group and experimental group.In the experimental group,0.5 ml of mycoplasma gallisepticum bacteria solution which was cultured to logarithmic growth stage and had been concentrated to a final concentration of 1.0×109 ccu/mL was dripped through nasal cavity and eye drops for three consecutive days,while the blank control group was treated with PBS buffer solution in the same dose,manner and days as the virus-attacking bacteria solution in the experimental group.After artificial infection,the serum antibody of Mycoplasma synoviae was detected.The results showed that all chickens in the experimental group were positive,while those in the control group were negative during the test period.During the test period,the body temperature of the two groups of chickens was monitored,and the body temperature of the test group was significantly higher than that of the control group.At the beginning of the experiment,there was no difference in weight between the two groups of chickens,but with the progress of the experiment,the weight gain of the experimental group was significantly different from that of the control group(P<0.05).In addition,the clinical symptoms and autopsy results of chickens in the experimental group are consistent with the typical clinical characteristics of chicken synovial bursa mycoplasma disease.The autopsy tissues were amplified with specific primers of mycoplasma synoviae,and the amplification results of the control group and the blank PCR amplification group were all negative,that is,the pathological model of chicken synovial bursa mycoplasma disease was successfully replicated in this experiment.3.In this experiment,the high-throughput transcriptome sequencing method was selected,and the tracheal tissue of host chicken infected by M.synoviae was used as the sequencing sample to explore the differential genes and key metabolic networks of the host after M.synoviae infection,so as to lay the experimental foundation for revealing the immune system response of the host and regulating the defense mechanism after M.synoviae invasion.The results showed that compared with the chickens of the blank control group,351 genes were up-regulated and 74 genes were down-regulated at the transcription level in the experimental group after infection with M.synoviae.Ten genes were randomly selected from the identified differential genes by fluorescence quantitative PCR,the quantitative results showed that the relative quantitative results of 10 genes(MMP9,MMP10,MMP13,Bcl-2A1,GRP,PHLDA2,GTSE1,EDPE,ZAP70 and PDK4)were consistent with those of transcriptome sequencing.Differential genes represented by Bcl-2A1,MMP13,MMP9,and MMP10 were detected to interact with cytokine-cytokine receptor interactions,intestinal immune network for IgA production,Toll-like receptor signaling pathway,cell adhesion molecule,Wnt signaling pathway,adhesion spot kinase signaling pathway/FAK,extracellular matrix-receptor interaction,The KEGG pathways represented by the C-type lectin receptor signaling pathways were enriched to,and most of the above KEGG pathways were located in the center of the network of pathway interaction,suggesting that the above pathways interacted synergistically in response to pathogen invasion when M.synoviae infected the chicken host.Some genes in the MMP s matrix metalloproteinase family interact harmoniously with the extracellular matrix-receptor interaction pathway,suggesting that these genes may play important roles in M.synoviae-induced arthritis.Differential genes,key metabolic pathways and the pathogenic mechanism of M.synovialis need further investigation. |
