H_(18)细胞中Epstein-Barr病毒DNA复制的抑制和恢复

采用~(32)P标记的EBV DNA BamH Ⅰ-W片段为探针,通过细胞点杂交测出每个H_(18)细胞中EBV基因组拷贝数约207个。在PAA存在下,这些病毒基因组数快速下降。每毫升细胞培液中加75γPAA后第11天,每个细胞中EBV基因组平均拷贝数降到17个,只占未处理细胞的8%,而后既使继续处理也稳定地维持在该水平。然而EBV-VCA的合成被完全地抑制了,只是EBV-EA的合成不受影响。如去除PAA,第3天时细胞中EBV基因组数可恢复到对照组的29%,而第40天则可恢复到90%。但是在去除PAA处理的同时加n-BA处理则明显地抑制这种恢复。一般认为EBV附加体DNA的复制由宿主细胞DNA多聚酶催化,病毒线状DNA由病毒诱导的PAA敏感的DNA多聚酶复制。由于n-BA能有效地阻碍宿主的DNA复制功能,因而我们的实验结果提示,宿主细胞和病毒诱导的DNA多聚酶??可能都参与了去除PAA处理后的H_(18)细胞中EBV DNA的恢复。

INHIBITION AND REVERSION OF EPSTEIN-BARR VIRUS DNA REPLICATION IN H_(18) CELL LINE

EBV genome equivalents per H~(18) cellwere estimated as about 207 by cell spothybridization with EBV DNA BamHI-Wfragment as probe and dropped abruptly withthe treatment of PAA.By day 11 after ad-ding PAA at a concentration of 75 Y/ml,theaverage number of EBV genome equivalentper cell decreased to 17,only about 8% ofthe untreated cell (Fig.3).and then main-tained at this level constantly under conti-nuous treatment,while the synthesis of EBVVCA was completely inhibited,but that ofEA was not affected.Removal of the drugat day 3 allowed a recovery to 29% of thegenome equivalent of the control value and.at day 40 to 90%.Whereas retreatmentwith n-butyrate after removal of PAA inter-fered with such recovery significantly (Fig.5).It is commonly believed that the replicationof EBV episome is mediated by host-cell DNApolymerase and the synthesis of viral linearDNA is mediated by the virus-induced PAA-sensitive DNA polymerase.Since n-butyratecan effectively prevent the host DNA repli-cation apparatus,therefore our results suggestthat both the host and virus-induced DNApolymerase might play a role in the recoveryof EBV DNA content in H~(18) cells after re-moval of PAA treatment.