Latency pattern of Epstein‐Barr virus and methylation status in Epstein‐Barr virus‐associated hemophagocytic syndrome

Abstract

Expression of different panels of latent gene transcripts is controlled by usage of three distinct Epstein-Barr virus (EBV) nuclear antigen (EBNA) promoters (Wp, Cp, and Qp). EBV-associated hemophagocytic syndrome, which is often a fatal disease and generally occurs after primary EBV infection, is characterized by monoclonal or oligoclonal proliferation of EBV-infected T cells. The latency pattern and EBNA promoter (Wp, Cp, and Qp) usage in EBV-infected cells from three patients with EBV-associated hemophagocytic syndrome were examined by reverse transcription-polymerase chain reaction (PCR). Three samples from the patients expressed EBER, EBNA1, EBNA2, latent membrane protein (LMP)1, and LMP2A transcripts. The transcripts of EBNA1 were initiated from not only Wp/Cp but also Qp. Lytic cycle Fp-initiated EBNA1 and EBV lytic gene BZLF1 transcripts were not detected. The methylation statuses of three EBNA promoters in three patients with EBV-associated hemophagocytic syndrome and in two patients with infectious mononucleosis were also analyzed using bisulfite PCR analysis. Wp was hypermethylated, and Qp was unmethylated in both diseases. Cp was highly methylated in EBV-associated hemophagocytic syndrome, however, whereas Cp was almost unmethylated in infectious mononucleosis. These results suggest that there may be distinct EBV-infected cell populations in EBV-associated hemophagocytic syndrome, which exhibit different patterns of EBV latent gene expression. The methylation status in Cp and phenotype of EBV-infected cells may be critical differences in EBV-associated hemophagocytic syndrome and infectious mononucleosis.

Rapid determination of Epstein–Barr virus latent or lytic infection in single human cells using in situ hybridization

“…44,50 Moreover, the presence of small numbers of episomal and chromosomally integrated EBV copies was observed in cells of newly transformed mantle cell lymphoma cell lines (Drs ME Williams and DG Bebb, personal communication), supporting the view that EBV integration mechanisms may be initiated shortly after infection. Latent membrane protein 1 is generally regarded to be a marker of latent viral infection, 51 its expression was seen in all latently infected cell lines and was associated with EBV DNA signal types 1-3, confirming that these patterns were representative of latent infection.…”

Hemophagocytic lymphohistiocytosis (HLH): A heterogeneous spectrum of cytokine-driven immune disorders

“…EBV-HLH engrafted mice could be distinguished from CAEBVengrafted mice by a more frequently fatal and aggressive course of the disease, with excessively higher levels of IFN-g and IL-8, and internal hemorrhaging, indicative of severe coagulopathy. EBV gene expression studies revealed that the engrafted EBV + T cells retained latency type II characteristics, as described in some patients with EBV-HLH [84,85]. In this latency type the highly immunogenic EBNA3 genes, that encode immunodominant epitopes, are not expressed, suggesting an inability for CD8 + T cells to efficiently recognize and remove EBV-infected cells, thus resulting in persistent antigenemia, stimulating hyperactivation of the immune system [81].…”

Viral epigenomes in human tumorigenesis

“…Four promoters (Cp, Wp, Qp and Fp) that drive EBNA1 expression have been described (Tao et al, 1998), and there is evidence that DNA methylation regulates the expression of this gene and ultimately defines the type of latency stage. CpG methylation switches off gene expression and induces the alternative transcription of EBNA1 from various promoters in the different latency stages that, at the same time, are associated with the pathology that the virus induces, from a simple infection to a lymphoma or carcinoma (Li and Minarovits, 2003;Yoshioka et al, 2003;Niller et al, 2008). Although Wp, Cp and Fp have been found methylated in a specific latency type, Qp remains unmethylated, irrespective of its activity, and is thought to be regulated by a putative repressor protein and specific histone modifications (Tao et al, 1998;Paulson and Speck, 1999;Salamon et al, 2001;Li and Minarovits, 2003;Tao and Robertson, 2003;Minarovits, 2006;Fejer et al, 2008;Fernandez et al, 2009).…”