Synergistic Pathogenicity Of Avian Leukosis Virus Subgroup J And Marek's Disease Virus

In recent years,the synergistic infectionof avian leukosis virus subgroup J(ALV-J)and Marek's disease virus(MDV)occurs widely,and has caused serious losses to the poultry industry in China,however,the synergistic mechanism of ALV-J and MDV is still unknown.In this study,wefirstly demonstrated that ALV-J and MDV have the ability to infect the same cell.Next,by the analysis of the coinfection of ALV-J and MDV at transcription level and protein expression level,cytokines and histopathology and single infection difference analysis,ALV-J and MDV showed synergistic replication,infection and pathogenicity.In order to reveal the mechanism of coinfection,joint prevention and control and other virus infection mechanism between cooperative lay a scientific foundation.Specific pathogen free(SPF)chicken embryos at 10-day old were preparatedfor chicken embryo fibroblast(CEF).Four experimental groups were designed as :ALV-J+MDV infection group,ALV-J infection group,MDV infection group and blank control group.By PCR test,indirect immunofluorescence(IFA)and avian leukemia antigen(p27)detection of virus,Fluorescence quantitative results showed that at 24 h,ALV-J and MDV began to copy,and at 72 h,the RNA level of MDV and ALV-J in coinfection group is significant higher that those in sigle infection group.The result demonstrated the the viruses in coinfection group had stronger ability of transcription,and caused more serious damage to cells,resulting from the viruses synergistic transcription level.Western Blot showed that the expression of cytoplasmic protein in the coinfected group was significantly higher than that in the untreated group,and the expression of the protein was promoted by the co-infection group.The results showed that coinfection group lesions appear ahead of time 24 h,plaque is more obvious when compared with MDV or ALV-J infection group alone.At the same time,the amount of replication of virus in coinfection group is more increasing than single infection group.The result confirmed that MDV and ALV-J can infect the same cell,and has synergistic infection..In vitro experiments,three kinds of cytokines(IL-6,IL-10,TGF-?)were selected,which indicated that co-infection could promote the inflammatory response and increase the immunosuppressive effect,Promote cell differentiation,the two viruses can effectively change the cell microenvironment to promote viral expression.To further validate the synergistic effect of MDV and ALV-J,we conducted an in vivo infection experiment and killed three consecutive shots at 1,3,5 weeks of age after inoculation.It was further demonstrateded that the two viruses have synergistic pathogenic effects observed by histopathological and hematological analysis.The blood test showed that the number of peripheral white blood cells in the coinfection group was much higher than single infection group,significantly higher than the control group.By clinical pathology,histopathology of dynamic pathology research,the total death rate in the coinfection group was 20%,and in ALV-J group and MDV group,the death rate was 3.33% and,10%,respectively,,at the beginning of the 3 week and the second week.The results showed that the liver,spleen and kidney of the coinfection group increased slightly from 2 to 4weeks.All tissues and organs in 2 weeks began to appear to naive lymphocytes,large and small lymphocytes mainly inflammatory infiltration of the foci [to be clear is the inflammatory lesions or tumor foci.To 4 to 5 weeks the most obvious,co-infection than the incidence of infection alone as early as 1 to 2 weeks,the lesion is more obvious.Suggesting that co-infection can increase the initial inflammatory response,so that mortality increases,speed up the process of tumorigenesis.In this study,the synergistic effects of ALV-J and MDV were revealed from different levels and aspects.Not only for the further study of ALV-J and MDV coordination mechanism for a clear direction,it will provide the scientific basis for avian tumors or other disease research,to provide new ideas for the prevention and treatment of avian tumor diseases.