[Sequence analysis of the CTL epitopes in transmembrane region of latent membrane protein 2 of Epstein-Barr virus derived from nasopharyngeal carcinoma cells].
OBJECTIVE
Epstein-Barr virus (EBV) in nasopharyngeal carcinoma (NPC) cells expresses Epstein-Barr nuclear antigen 1 (EBNA1), latent membrane protein 1 (LMP1), and LMP2. LMP2 is an ideal target for immunotherapy because LMP2 mRNA is detected in 100% nasopharyngeal carcinoma cells and LMP2 protein shows stronger immunogenity than the rest 2 viral proteins. This study was to analyze the sequence of CTL epitopes in the transmembrane region of LMP2 to optimize LMP2-targeted immunotherapy.


METHODS
Genomic DNA was extracted from 20 biopsies of NPC and 3 biopsies of normal nasopharynx from Cantonese. The transmembrane region of LMP2 gene was amplified with hemi-nest polymerase chain reaction (PCR), and then sequenced directly.


RESULTS
As compared with prototype B95.8 cells, the transmembrane region of LMP2 gene, derived from Cantonese NPC and normal nasopharynx tissues, had 14 base pair substitutions, resulting in 6 amino acid substitutions. Among these substitutions, 3 changed amino acids were located in 4 HLA-restricted CTL epitopes (SSC, TYG, CLG, and VMS). Among these polymorphisms, the VMS variation was first identified. The sequence changes of the LMP2 derived from NPC was the same as those of the LMP2 from normal nasopharynx, indicating that those variations were due to geographic-associated polymorphisms rather than NPC-associated mutations.


CONCLUSIONS
Polymorphisms of LMP2 exist in EBV derived from Cantonese, resulting in 4 CTL epitope variations, which implicates that the effect of LMP2 polymorphisms should be considered when LMP2-targeted vaccine is designed for immunotherapy.
Zhang
Nian-Hua
NH
State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, 510060, P. R. China.
Zhang
Xiao-Shi
XS
Li
Jiang
J
Zhang
Ru-Hua
RH
Gao
Yan-Fang
YF
Zeng
Mu-Sheng
MS