| Sheep respiratory disease is a common clinical disease.The main clinical symptoms include depression,anorexia,hyperthermia,cough,dyspnea and respiratory tract secretions.It was found that Mycoplasma ovipneummoniae(Mo),Pasteurella multocida(Pm),Mycoplasma ovipneummoniae(Mo),Mannheimia hyopneumoniae(Mh),Klebsiella pneumoniae(k.pn),Streptococcus pneumoniae(S.pn)were the main pathogens causing sheep pneumonia.Especially Mycoplasma pneumoniae has a high prevalence in clinical practice.Sheep husbandry is an important part of animal husbandry in Ningxia.In recent years,however,there are few reports about the present epidemic situation,diversity of pathogen of sheep respiratory diseases,the main pathological changes after sheep induced by Mycoplasma pneumoniae,the main target organs infected and the immunological changes of the main target organs in Ningxia.Therefore,the study conducts on the above issue.The test results of the experiment are as follows:1.In order to research the incidence and pathogenic diversity of sheep respiratory diseases in different Ningxia regions,the incidence of sheep respiratory diseases in main sheep breeding counties/areas was investigated and counted on the spot,and the collected nasal swabs,lungs,trachea,pericardial fluid and other samples were detected and identified by molecular biological methods.The results showed that a total of 236 were affected among 1180 sheep,with an incidence rate of 20.26%.Respiratory diseases mainly occur in sheep aged 2-7 months.The highest rate of Mo infection was 69.52%among single pathogen infections,the highest rate of Mo mixed with Pm infection was 10.48%among 2 pathogens infections,and the highest rate of Mo mixed with Pm and Mh infection was 3.81%among 3 pathogens infections.The results showed that Mo infection was found in all seven main sheep breeding counties/districts in Ningxia,and there were multiple pathogen mixed infections of Pm,Mh,K.pn,and S.pn.2.A total of 105 samples were collected from 13 large-scale farms in different regions for pathogen isolation and identification.Different internal organs mono-infected by Mo were selected for pathological dissection and analysis of histopathological changes.The results showed that 13 strains of Mo were isolated from the samples collected from 13 farms.The lesions caused by Mo are mainly in the lungs and trachea,with severe substantial lesion in the upper lobe of the lungs,adhesion between the lungs and the thoracic cavity,congestion in some areas of the lungs,and a large amount of foamy mucus in the trachea and bronchi.The histopathological changes of lung and bronchus showed epithelial cell necrosis,abscission and hyperplasia,a large number of inflammatory cell infiltration in bronchial cavity and alveolar cavity,edema and inflammatory cell infiltration in the lamina propria of bronchial and tracheal mucosa.3.In order to explore the main target organs colonized by Mo,immunohistochemical technique was used to study the pathogen localization of Mo in different internal organs.The results showed that the proportion of Mo positive area in lung tissue was the largest(5.22%),followed by that in bronchus(4.91%),and that in trachea(1.42%).There was extremely significant difference the positive percentage of Mo them between heart,liver,kidney and spleen(P<0.01).Mo existed in the pathological sections of various visceral tissues,but the main organs or tissues were lung,bronchus and trachea.4.In order to explore the changes of immune response of target organs induced by Mo,the mRNA expression of cytokines(IL-1,IL-2,IL-4,IL-6,IL-10,IL-12,TNF-α,IFN-γ)in target organs were detected by RT-PCR.The results showed that the up-regulated factors of mRNA expression in tracheal tissue included IL-1β,IL-6,IL-10,IL-12 and NF-κB.The up-regulated factors of mRNA expression in the bronchus included IL-1β,IL-2,IL-10,IL-12,TNF-α,IFN-y and NF-κB.The up-regulated factors of mRNA expression in the apical lobe included IL-1β,TNF-α,IFN-y and NF-κB.The up-regulated factors of mRNA expression in pulmonary heart lobe included IL-1β,IL-6,TNF-α,IFN-γ and NF-κB.The upregulated factors of mRNA expression in pulmonary septum included IL-1β and NF-κB.The study found that the mRNA expression of IL-1β and NF-κB was positively correlated with the degree of visceral organ lesions.To sum up,sheep respiratory diseases in Ningxia are mainly caused by sheep Mo infection,and the pathogens are diverse.In this study,13 Mo Ningxia isolates were isolated and identified.Histopathological and immunohistochemical analysis showed that the main target organs infected by Mo were lung,bronchus and trachea.The expression of cytokines in target organs was up-regulated in varying degrees,which was related to pathological changes.The results provide a reference for the research on the epidemic regularity,pathogenesis,prevention and control ofMycoplasma ovipneummoniae in Ningxia. |
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