| In order to study the histopathological characteristics of gastrohepatic lymph nodes infected by African swine fever virus（ASFV）and the relationship between extracelluer vesicles（EVs）and ASFV.In the experiment,9 healthy SPF pigs of 12 weeks of age were selected and randomly divided into control group,low-dose group and high-dose group.Low-dose group and high-dose group were injected intramuscularly with 103HAD50and104HAD50African swine fever virus HLJ/18 strains.After the experiment,the gastrohepatic lymph nodes were taken for HE staining,reticular fiber staining,immunohistochemistry,immunofluorescence,transmission electron microscopy and other techniques to observe and analyze the pathological characteristics of gastrohepatic lymph nodes and the morphological relationship between extracellular vesicles and the virus.The results showed that hemorrhage was severe after infection of ASFV in stomach and liver lymph nodes,normal cell structure was destroyed,apoptosis and mitochondrial damage occurred,and the higher the virus dose,the more obvious the pathological changes.EVs play a role in assisting the transportation in virus infection,helping the virus to escape host immunity,which is conducive to virus infection.The results of the study lay the foundation for the in-depth study of ASF histopathology and provide references for related research on the mechanism of ASFV infection.ExperimentΙHistopathological changes in gastrohepatic lymph nodes infected by ASFVIn order to study the characteristics of histopathological changes in gastrohepatic lymph nodes infected by African swine fever virus（ASFV）,and to analyze the differences in pathological changes caused by different virus doses.In the experiment,3 groups of SPF pigs were challenged with gastrohepatic lymph nodes,and the pathological changes were observed and analyzed by HE staining,reticular fiber staining and transmission electron microscopy.The results showed that the normal structure of gastrohepatic lymph nodes infected with ASFV was destroyed,the subcapsular,trabecular and cortical lymph nodes were congested,hemorrhage was serious,and inflammatory cells increased.The pathological changes of gastrohepatic lymph nodes in the high-dose group and the lower-dose group were more obvious.Compared with the normal group,the reticular fibers of gastrohepatic lymph nodes in the low-dose group and the high-dose group became thicker,and the number of fibers increased,and the higher the virus dose,the number also increased.A large number of ASFV particles were found under transmission electron microscopy,mainly distributed in macrophages.The nuclear structure of macrophages and lymphocytes was destroyed,the nucleus was shrunk and deformed,chromatin was concentrated and concentrated,and mitochondria appeared swelling,defects,and vacuolation.Some cells undergo apoptosis.ExperimentⅡStudy on the role of extracellular vesicles in the process of ASFV infection of gastrohepatic lymph nodes-ultrastructuralIn order to explore the morphological relationship between extracelluer vesicles（EVs）derived from macrophages and lymphocytes and ASFV,as well as to observe the ultrastructure of extracellular vesicles,we tested the gastrohepatic lymph nodes of three groups of SPF pigs after challenge.Using the specific markers CD63 and TSG101 of multivesicular bodies and their exosomes for immunohistochemistry and immunofluorescence,combined with transmission electron microscopy,the location and ultrastructure of extracellular vesicles were observed and analyzed.The results show that the exosomes are mainly distributed around lymphocytes and macrophages,and the number of exosomes is related to the ASFV infection dose.The higher the virus dose,the greater the number of exosomes,and the presence of virus particles in multiple vesicles was observed under the electron microscope,microvesicles encapsulate virus particles to assist the spread of the virus and other phenomena,drawing a pattern diagram of the ASFV infection process in macrophages and the morphological relationship with extracellular vesicles. |
