Study On The Infection And Pathogenic Characteristics Of Chikungunya Virus In Adult Tree Shrew

Chikungunya virus(CHIKV)belongs to the single-stranded positive-strand RNA virus of the genus Actinovirus.Chikungunya virus mainly causes polyarthritis through Aedes mosquito transmission,and belongs to a class of acute infectious diseases called Chikungunya fever.At present,CHIKV is mainly popular in Africa and Southeast Asia.It is easy to cause an explosive epidemic through mosquito-borne transmission.Currently,there are still no targeted vaccines and effective therapeutic drugs,which has become one of the most important public health problems in the world.The pathogenesis of polymorphic arthritis caused by CHIKV infection remains unclear,mainly due to the lack of a small animal model capable of simulating real human infection with CHIKV.Although non-human primate models and mouse models play an important role in the pathogenesis,antibody and vaccine research of CHIKV,there are certain defects and deficiencies in clinical characterization and kinship.Tree shrews have the characteristics of small size,rapid reproduction,physiological anatomy and immune response,which are highly similar to humans.Tree shrews have unique advantages for human viral infection and pathogenic mechanism research.At present,there are few reports on the CHIKV infection tree shrew model.Based on this,this paper carried out the research on the infection and pathogenic characteristics of Chikungunya virus in adult tree shrews.First,we selected adult tree shrews to use subcutaneous injection of 105 pfu/ml of CHIKV virus to collect various types of body fluids at different times after inoculation.RT-q PCR showed that sputum persisted in the first week.The viral load was 103-107pfu/ml,showing a gradual decline trend from 1d to 7d.The results of tree body fluid test showed that the virus could be detected in tears,saliva,urine,and feces for 5-21 days.At the same time,the tree shrews were infected with CHIKV,brain,heart,liver,skin,muscles and bones.Seven tissues of the prostate showed relative susceptibility.RT-q PCR analysis showed that 7 tissues detected 5-21 days of virus presence;tissue immunofluorescence assay showed that CHIKV was widely present in susceptible tissues on the 5th day after infection.Protein.Finally,positive and negative strands were detected.After the infection of CHIKV,the presence of viral negative strands was detected in the brain,liver and heart for the first 21 days.It was confirmed that CHIKV replicated in the tree mites.Infected with CHIKV.Secondly,in order to further study the pathogenicity of CHIKV infected tree shrews,we analyzed the body temperature and body weight changes of tree shrews at different times after virus inoculation.The results showed that the tree shrews began to appear on the second day after infection with CHIKV for 3-4 days,and the body temperature decreased significantly and the body weight decreased.The results of blood stasis and blood biochemical changes showed that white blood cell count(WBC),lymphocytes(LYM),monocytes(MON)and neutrophils(Gran)showed a downward trend for 3 days during the acute phase,and then returned to normal;aspartate aminotransferase(AST)and alanine in blood biochemical tests Acid transaminase(ALT)also increased significantly on the 2nd day after infection,and returned to normal level on the 6th day.Hematology tests showed a similar trend to humans;at the same time,it appeared on days 2-6 after infection.Different degrees of rash,joint swelling,and hair loss are typical symptoms that are not easily exhibited in other models.It has been confirmed by the above experiments that CHIKV can produce pathogenic characteristics similar to humans in tree shrews.In order to further detect the tissue damage and pathogenesis of tree shrews after infection with CHIKV,we detected the susceptible tissues of tree shrews in the first 21 days after infection by pathological detection and immunofluorescence detection,and found that inflammatory in susceptibility tissues Typical pathological lesions such as cell infiltration,local edema,and vacuolar degeneration,among which the degree of tissue damage is highest between the 5th and 14 th day after infection,and the fluorescence detection also shows a relatively high protein distribution.The results are related to humans and NHP.The model was consistently reported;more complex pathological damage and extensive protein distribution occurred in the prostate tissue.In terms of pathogenic mechanism,we performed transcriptome analysis on peripheral blood lymphocytes of tree shrews in the first 21 days after infection,and conducted preliminary Q-PCR verification on the transcriptome results,and found that the acute phase and the recovery phase produced similar to humans.Cytokine and chemokine levels were elevated and Q-PCR validation results were identical to transcriptome results.In summary,we have initially established a model of infectious and pathogenic characteristics of the adult-generation tree shrews in acute and convalescent CHIKV infection.The establishment of the CHIKV tree model allows us to better understand the interaction between CHIKV and the host.By using animal models,we can understand the immune response,pathogenesis,and test drug efficacy.It can also help us to screen out effective drugs and shorten the cycle and cost of new drug development and clinical trials in the study of CHIKV disease.In general,animal models can help us understand new aspects of disease biology in complex systems that cannot be replicated in vitro.