Colacino J M, Flowers C C, Menna J, O'Callaghan D J, Staczek J
Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130.
Virology. 1989 Dec;173(2):566-80. doi: 10.1016/0042-6822(89)90568-0.
Restriction endonuclease (RE) mapping studies and molecular hybridization analyses were conducted to determine the molecular structure of the genome of equine cytomegalovirus (ECMV). The ECMV genome is a linear, double-stranded DNA with a molecular size of 126 +/- 0.6 MDa (189 kbp). A library of cloned BamHI, EcoRI, and HindIII fragments of the viral genome was used to construct RE maps. Individual 32P-labeled cloned DNA fragments were hybridized to Southern blots of viral genomic DNA digested to completion with BamHI, EcoRI, HindIII, or SalI. These analyses revealed that the ECMV genome consists of a 97-MDa unique long region which is bracketed by repeated sequences. At one terminus of the genome, a 21.3-MDa segment of repeated sequences with no apparent unique sequences was identified. At the other terminus, a 6-MDa unique region bracketed by 2.4-MDa repeat segments was identified. No submolar RE fragments were identified upon digestion of the ECMV genome with BamHI, EcoRI, HindIII, SalI, or other REs, including BclI, BglII, NruI, and XbaI. The genome possesses only two termini as judged by lambda exonuclease digestion and by T4 DNA polymerase end-labeling of the intact DNA followed by digestion with BamHI, EcoRI, HindIII, SalI, BclI, BglII, NruI, or XbaI. In addition, Southern blot analysis of DNA extracted from ECMV-infected rabbit kidney cells revealed that only one viral DNA fragment within the intracellular viral DNA pool contains fused genomic termini. Taken together, these observations indicate that the ECMV genome does not isomerize and suggest that the genome of ECMV may be unique among those of the herpesviruses and especially those of the betaherpesviruses (cytomegaloviruses) since it contains regions of extensive internal homology yet does not undergo isomerization. Lastly, the relatively small size of the viral genome indicates an evolutionary diversification among the cytomegaloviruses.
进行了限制性内切酶（RE）图谱分析和分子杂交分析，以确定马巨细胞病毒（ECMV）基因组的分子结构。ECMV基因组是线性双链DNA，分子大小为126±0.6 MDa（189 kbp）。使用病毒基因组的克隆BamHI、EcoRI和HindIII片段文库构建RE图谱。将单个32P标记的克隆DNA片段与用BamHI、EcoRI、HindIII或SalI完全消化的病毒基因组DNA的Southern印迹杂交。这些分析表明，ECMV基因组由一个97-MDa的独特长区域组成，该区域两侧为重复序列。在基因组的一个末端，鉴定出一个21.3-MDa的重复序列片段，没有明显的独特序列。在另一个末端，鉴定出一个6-MDa独特区域，两侧为2.4-MDa重复片段。用BamHI、EcoRI、HindIII、SalI或其他RE（包括BclI、BglII、NruI和XbaI）消化ECMV基因组后，未鉴定出亚摩尔RE片段。通过λ外切核酸酶消化以及完整DNA的T4 DNA聚合酶末端标记，然后用BamHI、EcoRI、HindIII、SalI、BclI、BglII、NruI或XbaI消化判断，基因组仅拥有两个末端。此外，对从ECMV感染的兔肾细胞中提取的DNA进行Southern印迹分析表明，细胞内病毒DNA池中只有一个病毒DNA片段包含融合的基因组末端。综上所述，这些观察结果表明ECMV基因组不会异构化，并表明ECMV基因组在疱疹病毒中，尤其是在β疱疹病毒（巨细胞病毒）中可能是独特的，因为它包含广泛的内部同源区域但不会发生异构化。最后，病毒基因组相对较小的大小表明巨细胞病毒之间存在进化多样性。
