Epstein-Barr virus lytic cycle involvement in diffuse large B cell lymphoma.

Epstein-Barr virus (EBV)-mediated B cell transformation is achieved predominantly through the action of latent proteins, but recent evidence suggests that lytic EBV replication has also a certain pathogenic role in lymphomagenesis, at least in the early phases of cell transformation. Particularly, in diffuse large B cell lymphoma (DLBCL), the EBV lytic cycle is by and large unexplored, so to disclose lytic cell contribution to lymphomagenesis, our aim was to evaluate viral early and late lytic gene expression in relation to several immune response markers in a series of EBV+ DLBCL from Argentina. An unexpected number of cells expressed lytic transcripts, being transcribed at the BZLF1, BHRF1, and BLLF1 locus, by real-time quantitative polymerase chain reaction. This lytic antigen expression was confirmed by immunohistochemical staining for BMRF1 early lytic protein, and a positive correlation between lytic and latent genes was confirmed, revealing a close link between their expressions in EBV+ DLBCL pathogenesis. Remarkably, BZLF1 displayed a negative correlation with CD4 cell counts, and this could be in part justified by the restriction of antigen presentation previously reported. The direct correlation for the late lytic gene BLLF1 and IFNγ in this series could represent a specific response directed towards this antigen. Interleukin 10 transcripts also displayed a positive correlation with lytic expression, indicating that regulatory mechanisms could be also involved on EBV-associated DLBCL pathogenesis in our series. Complete lytic reactivation in EBV-positive tumours could potentially kill EBV-positive malignant cells, providing a tool to promote tumour cell killing mediated by EBV as a complementary treatment strategy.

A novel recombinant variant of latent membrane protein 1 from Epstein Barr virus in Argentina denotes phylogeographical association.

AIM: To study LMP1 variants distribution among children with EBV+ malignant and benign conditions as well as in healthy carriers. METHODS: Oral secretions and blood cells from 31 children with IM, and biopsies from 14 EBV+ reactive lymphoid hyperplasia and 33 EBV+ lymphomas were included. LMP1 was amplified by nested PCR and sequenced. Phylogenetic reconstructions were made under Maximun Likelihood, Bayesian and coalescent algorithms. RESULTS: Six clades were defined (China1, China2, Med-, Alaskan, B95.8 and Argentine). Argentine variants, the most prevalent (46%), harbored 3 distinctive mutations and were a recombination between Raji and China1. Despite no pathology or compartment associations were observed for LMP1, the Argentine clade showed a phylogeographic association with our region. LMP1 estimated evolution rate was 8.591x10-5s/s/y and the estimated tMRCA for Raji and Argentine was 136ybp. CONCLUSIONS: An LMP1 Argentine clade was defined. LMP1 evolutionary rate was higher than expected for herpesviruses. The tMRCA for Raji and the Argentine agrees with African immigration and could explain the recombinant nature of the Argentine variant.

LMP1 promoter sequence analysis in Epstein Barr virus pediatric infection reveals preferential circulation of B95.8 related variants in Argentina.

The Epstein Barr virus (EBV) is associated with several lymphoid and epithelial malignancies such as Hodgkin and Burkitt lymphoma or nasopharyngeal carcinoma and it is also the etiological agent of infectious mononucleosis (IM). Transcriptional regulation of the viral oncoprotein LMP1, remains yet not fully understood. LMP1 expression can be initiated in an EBNA2 dependent or independent manner from ED-L1 or LT-R1 promoters. It has been proposed that sequence variation at ED-L1 region could be an important factor concerning LMP1 expression. In order to characterize the natural sequence variation of the ED-L1 promoter, and its relationship with neoplasia, 44 pediatric patients, 17 IM and 27 EBV-associated lymphoma cases from Argentina, were studied. Phylogenetic analysis showed 4 main clusters, namely B95.8, Raji, Cao and P3HR1. Most isolates, 80.3%, conformed the B95.8 group. Co-infection with more than one viral variant was detected in 5/17 IM cases, but no co-infections were detected among lymphoma cases. Moreover, co-infected IM cases exhibited differences between the ED-L1 sequences obtained from different anatomical compartments. Mutations confined to transcription factor binding sites such as SP1/SP3, CRE, AP2, C/EBP were found in similar proportions in 23 isolates from both benign and malignant samples, rendering the distribution of these mutations not significant among malignant samples.

Distinctive Epstein-Barr virus variants associated with benign and malignant pediatric pathologies: LMP1 sequence characterization and linkage with other viral gene polymorphisms.

The ubiquitous Epstein-Barr virus (EBV) is related to the development of lymphoma and is also the etiological agent for infectious mononucleosis (IM). Sequence variations in the gene encoding LMP1 have been deeply studied in different pathologies and geographic regions. Controversial results propose the existence of tumor-related variants, while others argued in favor of a geographical distribution of these variants. Reports assessing EBV variants in IM were performed in adult patients who displayed multiple variant infections. In the present study, LMP1 variants in 15 pediatric patients with IM and 20 pediatric patients with EBV-associated lymphomas from Argentina were analyzed as representatives of benign and malignant infections in children, respectively. A 3-month follow-up study of LMP1 variants in peripheral blood cells and in oral secretions of patients with IM was performed. Moreover, an integrated linkage analysis was performed with variants of EBNA1 and the promoter region of BZLF1. Similar sequence polymorphisms were detected in both pathological conditions, IM and lymphoma, but these differ from those previously described in healthy donors from Argentina and Brazil. The results suggest that certain LMP1 polymorphisms, namely, the 30-bp deletion and high copy number of the 33-bp repeats, are associated with EBV-related pathologies, either benign or malignant, instead of just being tumor related. Additionally, this is the first study to describe the Alaskan variant in EBV-related lymphomas that previously was restricted to nasopharyngeal carcinomas from North America.

EBNA1 sequences in Argentinean pediatric acute and latent Epstein-Barr virus infection reflect circulation of novel South American variants.

Epstein-Barr virus (EBV) is related to the development of lymphomas and is also the etiological agent for infectious mononucleosis (IM). Sequence variation of the EBNA1 gene, consistently expressed in all EBV-positive cells, has been widely studied. Based on the amino acid at codon 487 five major EBNA1 variants have been described, two closely related prototypic variants (P-ala and P-thr) and three variant sequences (V-leu, V-val, and V-pro). Sub-variants were then further classified based on mutations other than the originally described. While several studies proposed associations with tumors and/or anatomical compartments, others argued in favor of a geographical distribution of these variants. In the present study, EBNA1 variants in 11 pediatric patients with IM and 19 pediatric EBV lymphomas from Argentina were compared as representatives of benign and malignant infection in children, respectively. A 3-month follow-up study of EBNA1 variants in peripheral blood cells and in oral secretions of patients with IM was performed. A new V-ala variant which includes five V-ala sub-variants and three new V-leu sub-variants was described. These data favor the geographical association hypothesis since no evidence for a preferential compartment distribution of EBNA1 variants and sub-variants was found. This is the first study to characterize EBNA1 variants in pediatric patients with infection mononucleosis worldwide.

Epstein-Barr virus BZLF1 gene promoter variants in pediatric patients with acute infectious mononucleosis: its comparison with pediatric lymphomas.

Epstein-Barr virus genotypes can be distinguished by polymorphic variations in the genes encoding EBNA2, 3A, 3B, and 3C. The immediate early gene BZLF1 plays a key role in modulating the switch from latency to lytic replication and therefore enabling viral propagation. The aim of this study was to investigate and compare BZLF1 promoter sequence (Zp) variation in pediatric infectious mononucleosis (IM) and in pediatric EBV positive lymphoma biopsies. Zp was sequenced from peripheral blood mononuclear cells (PBMC) and throat swabs from 10 patients with IM at the time of diagnosis (D0) and during convalescence; and from 13 lymphoma biopsies. Zp - P and Zp - V3 variants were found in eight and one IM patients, as well as in five and six tumor biopsies, respectively. A correlation between viral genotype and Zp variant was found significant for Zp - V3 and EBV2 (P = 0.0002). One IM patient harbored two concomitant Zp variants. Regardless of anatomical compartment or stage of disease all IM patients displayed the same Zp variant along the course of the study. No new infections or adaptative selection of different variants was evidenced. A new Zp variant (Zp - V3 + 49) was described in two Hodgkin lymphomas, but not in IM. This is the first study to describe Zp variants compartmentalization in children with acute EBV infection and convalescence in a developing country; and comparing them with Zp variants in pediatric lymphomas from the same geographic area.

Epstein-Barr virus in breast carcinoma in Argentina.

CONTEXT: Because the etiology and progression of breast carcinoma remain unclear, novel mechanisms of disease pathogenesis need to be considered. Recent interest has focused on Epstein-Barr virus (EBV), an oncogenic ubiquitous herpesvirus. Investigations of this association could not only broaden understanding of breast cancer etiology but also have implications regarding early detection, treatment, and prevention. OBJECTIVE: To assess EBV presence in breast carcinoma in an Argentine series. DESIGN: Breast biopsy specimens of 69 women with breast carcinoma and fresh tumor tissue of 39 of these women were collected. As controls, 17 biopsy specimens of fibroadenomas, 9 of benign epithelial proliferation, 4 of atypical ductal hyperplasia, and 10 of usual ductal hyperplasia and 8 normal breast tissues from women were studied. The EBV-infected cells were identified by means of immunohistochemical analysis, using a monoclonal antibody against Epstein-Barr virus-encoded nuclear antigen 1 (EBNA-1). Polymerase chain reaction (PCR) was used to amplify EBV DNA, with primers that cover the EBV encoded RNA (EBER) and BamHIW regions. RESULTS: Nuclear expression of EBNA-1 was observed in tumor epithelial cells in 24 (35%) of the 69 cases. We confirmed both positive and negative immunohistochemical results by PCR in those cases where good quality DNA was also available, detecting amplification fragments of 108 base pairs (bp) from the EBER region and 122 bp from the BamHIW region. Neither immunohistochemical analysis nor PCR detected any positive EBV results in the control samples. CONCLUSIONS: Our results demonstrate the presence and expression of EBV restricted to epithelial tumor cells in a subset of breast carcinomas studied. However, no significant association was observed between EBV expression and worse clinical and pathologic patient characteristics.