Abstract
BackgroundNK/T cell lymphoma is an aggressive lymphoma almost always associated with EBV. BamHI-A rightward open reading frame 1 (BARF1) and BamHI-H rightward open reading frame 1 (BHRF1) are two EBV early genes, which may be involved in the oncogenicity of EBV. It has been found that V29A strains, a BARF1 mutant subtype, showed higher prevalence in NPC, which may suggest the association between this variation and nasopharyngeal carcinoma (NPC). To characterize the sequence variation patterns of the Epstein-Barr virus (EBV) early genes and to elucidate their association with NK/T cell lymphoma, we analyzed the sequences of BARF1 and BHRF1 in EBV-positive NK/T cell lymphoma samples from Northern China.MethodsIn situ hybridization (ISH) performed for EBV-encoded small RNA1 (EBER1) with specific digoxigenin-labeled probes was used to select the EBV positive lymphoma samples. Nested-polymerase chain reaction (nested-PCR) and DNA sequence analysis technique were used to obtain the sequences of BARF1 and BHRF1. The polymorphisms of these two genes were classified according to the signature changes and compared with the known corresponding EBV gene variation data.ResultsTwo major subtypes of BARF1 gene, designated as B95-8 and V29A subtype, were identified. B95-8 subtype was the dominant subtype. The V29A subtype had one consistent amino acid change at amino acid residue 29 (V → A). Compared with B95-8, AA change at 88 (L → V) of BHRF1 was found in the majority of the isolates, and AA79 (V → L) mutation in a few isolates. Functional domains of BARF1 and BHRF1 were highly conserved. The distributions of BARF1 and BHRF1 subtypes had no significant differences among different EBV-associated malignancies and healthy donors.ConclusionThe sequences of BARF1 and BHRF1 are highly conserved which may contribute to maintain the biological function of these two genes. There is no evidence that particular EBV substrains of BARF1 or BHRF1 is region-restricted or disease-specific.
Highlights
natural killer (NK)/T cell lymphoma is an aggressive lymphoma almost always associated with Epstein-Barr virus (EBV)
Sixty nine samples of NK/T cell lymphoma tissues were tested by EBER 1 in situ hybridization, and 57 cases (82.6 %) were EBV positive
Because of the difficulty in tissue availability and extensive necrosis in NK/T cell lymphoma tissues, only 47 and 53 EBV-positive samples were used for detecting BamHI-A rightward open reading frame 1 (BARF1) and BamHI-H rightward open reading frame 1 (BHRF1) sequence respectively
Summary
BamHI-A rightward open reading frame 1 (BARF1) and BamHI-H rightward open reading frame 1 (BHRF1) are two EBV early genes, which may be involved in the oncogenicity of EBV. To characterize the sequence variation patterns of the Epstein-Barr virus (EBV) early genes and to elucidate their association with NK/T cell lymphoma, we analyzed the sequences of BARF1 and BHRF1 in EBV-positive NK/T cell lymphoma samples from Northern China. Epstein-Barr virus (EBV) is a member of gamma herpes virus family and persistently infects B lymphocytes in more than 90 % population of adults [1]. Being a B-lymphotropic virus, EBV can infect NK/T cells [4] and is highly associated with natural killer (NK)/T cell lymphoma [5]. EBV is found in nearly 100 % nasal NK/T cell lymphoma but rarely in primary cutaneous NK/T cell lymphoma [6]
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