只有了解致命病毒的进化过程，我们才能有效地降低它们的伤害。一些常年生活在动物体内的病毒片段让我们看到，病毒们是怎样巧妙潜入了昆虫和其它动物的基因组里，随着动物们一起进化的。该研究发表在近期的《公共科学图书馆―遗传学》（PLoS Genetics）上。
来自洛克菲勒大学(Rockefeller University)的R.Gifford和牛津大学(Oxford University)的A.Katzourakis使用了先进的遗传学技术，分析昆虫、哺乳动物和鸟类的DNA数据库，寻找病毒基因组的片段，这些片段叫做内生病毒元件（EVEs）。两位科学家在其中发现了十个科的代表病毒，包括B型肝炎病毒、埃博拉、狂犬病、登革热等多种病毒都整合在动物基因组里。
Gifford认为，他们找到了某些病毒类群的前身。自1970年以来，科学家们一直致力于寻找逆转录病毒在动物基因组中的证据，很少有人关注那些非逆转录病毒中的内生病毒元件是怎样演化、怎样插入寄主的细胞核DNA的。
研究者们收集到的大部分病毒片段都已经不具备功能，成为俗称的“垃圾DNA”。然而他们发现，在它们进化史中的某些时间段，这些病毒片段被寄主启用过，可能是用作免疫防止感染相关病毒。研究者们特别强调，在昆虫基因组找到的内生病毒元件能帮助我们探索病毒间的进化联系，提供给我们寄主以及远古生态环境的信息。
原文出处：
PLoS Genetics doi:10.1371/journal.pgen.1001191
Endogenous Viral Elements in Animal Genomes
Aris Katzourakis1*, Robert J. Gifford2*
1 Department of Zoology, University of Oxford, Oxford, United Kingdom, 2 Aaron Diamond AIDS Research Center, New York, New York, United States of America
Integration into the nuclear genome of germ line cells can lead to vertical inheritance of retroviral genes as host alleles. For other viruses, germ line integration has only rarely been documented. Nonetheless, we identified endogenous viral elements (EVEs) derived from ten non-retroviral families by systematic in silico screening of animal genomes, including the first endogenous representatives of double-stranded RNA, reverse-transcribing DNA, and segmented RNA viruses, and the first endogenous DNA viruses in mammalian genomes. Phylogenetic and genomic analysis of EVEs across multiple host species revealed novel information about the origin and evolution of diverse virus groups. Furthermore, several of the elements identified here encode intact open reading frames or are expressed as mRNA. For one element in the primate lineage, we provide statistically robust evidence for exaptation. Our findings establish that genetic material derived from all known viral genome types and replication strategies can enter the animal germ line, greatly broadening the scope of paleovirological studies and indicating a more significant evolutionary role for gene flow from virus to animal genomes than has previously been recognized.
