摘要
根据鸡马立克氏病病毒（Marek′s disease virus,MDV）GA株的全基因组序列,设计合成了用于扩增MDVMeq、RLORF4、RLORF12及132bpr基因的引物,分别扩增4株MDV流行强毒株的高代次细胞毒株（L-SYp85C、L-MSp75C、L-CZp75C、L-ZYp75C）及相应亲本毒株（L-SY、L-MS、L-CZ、L-ZY）、MDV强毒J-1株、814疫苗株等10个毒株的Meq、RLORF4、RLORF12和132bpr基因。经克隆测序后,分析4个高代次细胞毒株中相应基因的变异,并与MDV强毒J-1株、814疫苗株及GenBank中已发表MDV毒株的相应序列进行比较。序列比对分析发现,L-CZp75C株Meq基因的第625位存在碱基C插入突变;L-ZYp75C株Meq基因第529位存在碱基C插入,且第602位缺失碱基T,从而致使Meq基因推导的相应氨基酸序列在第177~200位发生移码突变。L-SYp85C株RLORF4基因在第215~265位缺失51bp,致使该基因推导的氨基酸序列相应缺失17个氨基酸残基。分析RLORF12基因序列,发现L-MSp75C株在第67位存在碱基T缺失,814疫苗株在第18~86位缺失69 bp,缺失位置均位于复制起点（Origin of replication,,Ori）内;而L-ZYp75C毒株在RLORF12基因第168~174位存在独特的TGTTGGG碱基缺失。4个细胞高代次毒株的132 bpr基因的扩增结果表明,该基因在病毒基因组中的拷贝数明显增加,可达到10个拷贝以上。上述分析结果提示,4株MDV流行强毒株经体外连续传代后,MDV致瘤相关基因Meq、RLORF4、RLORF12和132bpr基因等发生了缺失突变或插入突变。
Recently, much work has been devoted to study MD-induced oncogenesis and the genes involved in this process. Among many genes in the MDV genome, several genes such as Meq, RLORF4, RLORF12, and 132bpr have been considered recently associated with virulence of MDV. In this paper, primers of Meq, RLORF4, RLORF12 and 132bpr genes were designed and synthesized, based on the pub- lished whole genome sequence of MDV strain GA. The genes of Meq, RLORF4 and RLORF12 from four Chinese epidemic MDV strains highly passaged on chicken embryo fibroblast （CEF）, i.e. L-SYp85C, L- MSp75C, L-CZp75C, and L-ZYp75C, as well as their corresponding parent strains, i.e. L-SY, L-MS, L- CZ, and L-ZY, the reference virulent strain J-1 and the vaccine strain 814 were amplified by PCR respectively. Then the PCR products of interest were cloned and sequenced respectively. The results of sequence comparison and analysis of Meq genes in the study indicated that Meq genes from the two strains L- ZYp75C and L-CZp75C contained single nucleotide insertion and deletion. The Meq gene from strain L- ZYp75C contained an extra cytidine （C） insertion at nucleotide position 529 and a single thymidine （T） deletion at nucleotide position 602, resulting in a frameshift mutation. And this frameshift mutation could lead to changes in deduced amino acid sequence from position 177 to 200 of Meq gene. The extra C insertion at nucleotide position 625 in Meq gene of strain L-CZp75C was also predicted to cause frameshift mutation in three overlapping genes （Meq, RLORF6 and 23KD genes）. The comparison of nucleotide sequences of RLORF4 genes in the study revealed that the RLORF4 gene of strain L-SYp85C contained a fragment deletion in Open Reading Frame （ORF） from nucleotide position 215 to 265, resulting in 17 amino acids deletions, which were not found in other sequenced strains. Comparison of nucleotide sequences of RLORF12 genes in the study revealed several mutations. The RLORF12 gene of strain L-MSp75C contained a single T deletion at nucleotide position 67 and of 814 vaccine strain a large fragment deletion from nucleotide position 18 to 86, both of the deletions located in Origin of replication site （Ori） of MDV genome. But strain L-ZYp75C possessed an unique ＂TGTTGGG＂ deletion in its RLORF12 gene. When the four Chinese epidemic MDV strains were serially passaged on CEF, the number of copies of the 132bp repeats increased from 2 to more than 10 copies. All of above results indicated that deletion and/or insertion mutation occurred in Meq, RLORF4, RLORF12 and 132bpr after serial passage of these four Chinese epidemic MDV strains on CEF.
出处
《病毒学报》
CAS
CSCD
北大核心
2009年第5期368-375,共8页
Chinese Journal of Virology
基金
重点实验室基本科研业务费(SKLVBP200819)
