Kienzle N, Sculley T B, Poulsen L, Buck M, Cross S, Raab-Traub N, Khanna R
EBV Unit, Queensland Institute of Medical Research, The Bancroft Centre, Herston, Queensland 4006, Australia.
J Virol. 1998 Aug;72(8):6614-20. doi: 10.1128/JVI.72.8.6614-6620.1998.
The Epstein-Barr virus (EBV)-encoded BARF0 open reading frame gene products are consistently expressed in EBV-positive Burkitt's lymphoma (BL) cell lines, nasopharyngeal carcinoma cell lines, and lymphoblastoid cell lines (LCLs). Here we show that the BARF0 sequence includes an HLA A*0201-restricted cytotoxic T-lymphocyte (CTL) epitope. By using theoretically predicted HLA A2 binding motifs and peptide-loaded antigen presentation-deficient T2 cells, polyclonal BARF0-specific CD8(+) CTLs were isolated from four different healthy EBV-seropositive donors but not from two seronegative donors. These CTL lines recognized the peptide epitope LLWAARPRL, which was found to be conserved in 33 of 34 virus strains originating from Caucasian, African, and Asian individuals. The BARF0-specific CTL lines could lyse EBV-negative BL cells stably transfected with the BARF0 gene but did not kill HLA A2-matched EBV-positive BL cells and LCLs in a standard 51Cr release assay. Reverse transcriptase PCR analysis demonstrated that these EBV-positive cell lines expressed significantly lower levels of BARF0 mRNA than transfected cells. This data indicated that the BARF0 epitope could be endogenously processed; however, antigen levels in the target cell were a limiting factor for the effective interaction between BARF0-expressing cells and CTLs. The limited expression of BARF0 antigen in EBV-infected BL cells and LCLs might contribute to the escape of immune recognition from virus-specific CTLs present in the host.
爱泼斯坦-巴尔病毒（EBV）编码的BARF0开放阅读框基因产物在EBV阳性的伯基特淋巴瘤（BL）细胞系、鼻咽癌细胞系和淋巴母细胞系（LCL）中持续表达。在此我们表明，BARF0序列包含一个HLA A*0201限制性细胞毒性T淋巴细胞（CTL）表位。通过使用理论预测的HLA A2结合基序和负载肽的抗原呈递缺陷型T2细胞，从四名不同的健康EBV血清反应阳性供体中分离出多克隆BARF0特异性CD8(+) CTL，但未从两名血清反应阴性供体中分离出。这些CTL系识别肽表位LLWAARPRL，发现该表位在源自高加索人、非洲人和亚洲人的34株病毒中的33株中保守。在标准的51Cr释放试验中，BARF0特异性CTL系可裂解稳定转染BARF0基因的EBV阴性BL细胞，但不杀伤HLA A2匹配的EBV阳性BL细胞和LCL。逆转录酶PCR分析表明，这些EBV阳性细胞系表达的BARF0 mRNA水平明显低于转染细胞。该数据表明，BARF0表位可被内源性加工；然而，靶细胞中的抗原水平是表达BARF0的细胞与CTL之间有效相互作用的限制因素。BARF0抗原在EBV感染的BL细胞和LCL中的有限表达可能有助于宿主中存在的病毒特异性CTL逃避免疫识别。
