title: Conserved mutation of Epstein-Barr virus-encoded BamHI-A Rightward Frame-1 (BARF1) gene in Indonesian nasopharyngeal carcinoma.
abstract: BACKGROUND
  BamHI-A rightward frame-1 (BARF1) is a carcinoma-specific Epstein-Barr virus (EBV) encoded oncogene. Here we describe the BARF1 sequence diversity in nasopharyngeal carcinoma (NPC), other EBV-related diseases and Indonesian healthy EBV carriers in relation to EBV genotype, viral load and serology markers. Nasopharyngeal brushings from 56 NPC cases, blood or tissue from 15 other EBV-related disorders, spontaneous B cell lines (LCL) from 5 Indonesian healthy individuals and several prototype EBV isolates were analysed by PCR-direct sequencing.
  
  
  RESULTS
  Most NPC isolates revealed specific BARF1 nucleotide changes compared to prototype B95-8 virus. At the protein level these mutations resulted in 3 main substitutions (V29A, W72G, H130R), which are not considered to cause gross tertiary structure alterations in the hexameric BARF1 protein. At least one amino acid conversion was detected in 80.3% of NPC samples compared to 33.3% of non-NPC samples (p < 0.001) and 40.0% of healthy LCLs (p = 0.074). NPC isolates also showed more frequent codon mutation than non-NPC samples. EBV strain typing revealed most isolates as EBV type 1. The viral load of either NPC or non-NPC samples was high, but only in non- NPC group it related to a particular BARF1 variant. Serology on NPC sera using IgA/EBNA-1 ELISA, IgA/VCA-p18 ELISA and immunoblot score showed no relation with BARF1 sequence diversity (p = 0.802, 0.382 and 0.058, respectively). NPC patients had variable antibody reactivity against purified hexameric NPC-derived BARF1 irrespective of the endogenous BARF1 sequence.
  
  
  CONCLUSIONS
  The sequence variation of BARF1 observed in Indonesian NPC patients and controls may reflect a natural selection of EBV strains unlikely to be predisposing to carcinogenesis. The conserved nature of BARF1 may reflect an important role in EBV (epithelial) persistence.
authors.affiliation: Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands. j.middeldorp@vumc.nl.
authors.forename: Susanna H
authors.initials: SH
authors.lastname: Hutajulu
authors.forename: Eveline K
authors.initials: EK
authors.lastname: Hoebe
authors.forename: Sandra Awm
authors.initials: SA
authors.lastname: Verkuijlen
authors.forename: Jajah
authors.initials: J
authors.lastname: Fachiroh
authors.forename: Bambang
authors.initials: B
authors.lastname: Hariwijanto
authors.forename: Sofia M
authors.initials: SM
authors.lastname: Haryana
authors.forename: Servi Jc
authors.initials: SJ
authors.lastname: Stevens
authors.forename: Astrid E
authors.initials: AE
authors.lastname: Greijer
authors.forename: Jaap M
authors.initials: JM
authors.lastname: Middeldorp