Tidona C A, Darai G
lnstitut für Medizinische Virologie, Universität Heidelberg, Federal Republic of Germany.
Virus Genes. 2000;21(1-2):77-81.
Iridoviruses belong to the group of large cytoplasmic deoxyriboviruses and infect either insects or vertebrates. In analogy to other large DNA viruses of eucaryotes it was found that iridoviruses encode a number of cellular protein homologues. The majority of these proteins represent orthologues of cellular enzymes involved in transcription, replication, and nucleotide metabolism. Others may have the potential to interfere with cell cycle regulation or immune defence mechanisms of the host. This raises the question about the phylogenetic origin of the corresponding viral genes. During the evolution of large cytoplasmic DNA viruses such as iridoviruses, poxviruses, and African swine fever virus the acquirement of cellular genes appears to be a crucial event. Each member of this group of viruses encodes a DNA polymerase, two subunits of the DNA-dependent RNA polymerase, and two subunits of the ribonucleotide reductase. It is important to note that all of these viral proteins show a high level of multidomain structure conservation as compared to their cellular orthologues. As a consequence the large cytoplasmic DNAviruses have the ability to replicate independently of the cellular nucleus in the cytoplasm of the infected cell. Assuming a common cellular origin of viral DNA polymerase genes the corresponding amino acid sequences were chosen to construct a phylogenetic tree showing the relatedness among large DNA viruses of eucaryotes.
虹彩病毒属于大型细胞质脱氧核糖病毒类，可感染昆虫或脊椎动物。与其他真核生物的大型DNA病毒类似，发现虹彩病毒编码许多细胞蛋白同源物。这些蛋白中的大多数代表参与转录、复制和核苷酸代谢的细胞酶的直系同源物。其他一些可能有干扰宿主细胞周期调控或免疫防御机制的潜力。这就引发了关于相应病毒基因的系统发育起源的问题。在虹彩病毒、痘病毒和非洲猪瘟病毒等大型细胞质DNA病毒的进化过程中，获取细胞基因似乎是一个关键事件。这类病毒的每个成员都编码一种DNA聚合酶、DNA依赖性RNA聚合酶的两个亚基以及核糖核苷酸还原酶的两个亚基。需要注意的是，与它们的细胞直系同源物相比，所有这些病毒蛋白都表现出高度的多结构域结构保守性。因此，大型细胞质DNA病毒能够在被感染细胞的细胞质中独立于细胞核进行复制。假设病毒DNA聚合酶基因有共同的细胞起源，选择相应的氨基酸序列构建一个系统发育树，以显示真核生物大型DNA病毒之间的亲缘关系。
