Dynamic Pathology and Antigen Location Study on Broiler Breeders with Coinfection of Marek's Disease Virus and Reticuloendotheliosis Virus

To further understand the generation and development of coinfection of Marek＇s disease virus （MDV） and reticuloendotheliosis virus （REV） in broiler breeders, and then find the method and optimal time of differential diagnosis for complex clinic multiple infection, the authors studied the pathohistological changes, apoptosis, immunohistochemistry （immunofluorescence）, and ultrastructure of tumor tissues of broiler breeders inoculated with MDV and REV. The study showed that proliferation of small lymphocytes was seen in the main organs at the age of 1 week, then immature lymphocytes, all kinds of lymphocytes, primitive reticulum cells, and Marek＇s disease cells （MDCs） were observed at 2-9 weeks. Apoptosis of lymphocytes could not be seen until the age of 10 weeks in the immune system. Immunohistochemistry detection showed that the positive signs of MDV and REV antigen were observed in the main organs at 2 weeks of age. Multi-morphology lymphocytes, MDV, and REV, mitotic figures and apoptosis of lymphocytes were observed with the help of transmission electron microscopy. MDV cooperating with REV promotes the course of disease of coinfection. Differential diagnosis can be done by immunohistochemistry in the early stage （before 2 weeks）, and histopathology in the late stage （post 4 weeks）. MDCs, primitive reticulum cells, immature lymphocytes, and two kinds of virions can serve as a basis for bistopathology differential diagnosis.

Comparison of Immune Effect of Four Commercial Marek's Disease Vaccines in Wenchang Chicken

Marek＇s disease（MD） is a lymphoproliferative disease of domestic chickens caused by a highly infectious,oncogenic alpha-herpesvirus known as Marek＇s disease virus（MDV）.The aim of this study was to compare the efficacy of four commercial MDV vaccines in Wenchang chicken.The 1-day old Wenchang chickens tested were injected with one of four different vaccines or not unvaccinated as control;five days later,they were then challenged by virulent MDV strain MD5.The results showed that,in comparison with HVT vaccines,the CVI988 vaccine gave the immunized chickens more potent immunities against challenges of MDV strain MD5.

Analysis of DNA methylation of CD79B in MDV-infected chicken spleen

Marek’s disease(MD),an immunosuppressive disease induced by Marek’s disease virus(MDV),provides an ideal model for studying diseases caused by a carcinogenic virus.CD79 B is a B-cell antigen receptor complex-associated protein β-chain precursor which is involved in the activation,proliferation,differentiation of B-cell and the transmission of downstream signals.This study analyzed CD79 B gene mRNA expression and methylation by two schemes#20(5′flanking to intron 1)and#27(intron 2 to intron 3),between MDV-infected tumorous spleens(TS)and non-infected spleens(NS).Results showed that average methylation levels of CpGs in #20 and #27 were higher in TS than in NS(P<0.05),while,CD79 B mRNA expression was lower in TS than in NS(P<0.01).Six of 40 CpG sites showed significantly(P<0.05)different methylation levels between TS and NS.Correlation analysis showed that the average methylation level rather than a single site methylation level in #20 affected(P<0.05)mRNA expression.Collectively,it was found that the change of CD79 B gene expression after MDV infection might be partly explained by modification of DNA methylation.

Study on the structure of heteropolymer pp38/pp24 and its enhancement on the bi-directional promoter upstream of pp38 gene in Marek’s disease virus

In the latest report, Chloramphenicol acetyltransferase (CAT) gene was used as a reporter to investi-gate the influence of pp38 on its upstream bi-directional promoter, and it was found that the co-expression of pp38 and pp24 can significantly enhance the transactivity of the bi-directional pro-moter between pp38 gene and 1.8-kb mRNA transcript in genome of Marek’s disease virus (MDV). In this study, enhanced green fluorescence protein (EGFP) gene was used as another reporter to further investigate the promoter activity. The transfection shows the promoter has the complete activity under the condition of co-expression of pp38 and pp24 in the same cells. Immunoprecipitation test was used to verify the structure of pp38/pp24 heteropolymer. The pp38-specific monoclonal antibody H19 was used in this test, and pp38, pp24 or both were prepared from the pcDNA-pp38, pcDNA-pp24 or pBud-pp38-pp24 transfected chicken embryonic fibroblast (CEF), respectively. Immunoprecipitation indicates that pp24 could be co-precipitated with pp38 by MabH19, implying that pp24 and pp38 were able to form a heteropolymer in the natural condition. The two separated tests clarify that pp38 and pp24 form a heteropolymer, which enhances the activity of the promoter.