最近科学家在兔子体内发现了一种古老的类似HIV病毒的存在。来自牛津大学的科学家发现这种特殊的慢病毒（lentivirus）属于和HIV非常接近的病毒家族，它们被保存在了欧洲兔的基因组内。这一发现刊登于本周的《Proceedings of the National Academy of Sciences》上，它将会改变科学家对于包括HIV在内的多种病毒进化的想法。
这种病毒叫做RELIK（兔内生慢病毒K），它是在兔子体内发现的第一种慢病毒：在此之前慢病毒只在猫、灵长类以及有蹄类中被发现过。
RELIK同时也是已知的最古老的类病毒，它们已经至少存在了7百万年了，而之前在猫类以及灵长类中发现的同类病毒只有1-2百万年历史。但是RELIK在慢病毒家族中最重要的特征在于它是唯一可以从一代传递给另一代的慢病毒。
科学家是在分析欧洲兔的种群基因数据过程中发现这种独特的病毒的。他们利用了数学技术来分析基因组、酶的结构以及已知的慢病毒蛋白质。利用以上这些技术得到的信息，科学家才最终确定他们发现了一种只在兔子体内存在的特殊慢病毒。
此项研究的主要负责人，牛津大学的Aris Katzourakis博士表示：“这就好像从地下发掘出一种被认为不存在的生物的化石。之前人们认为慢病毒不可能以内生的方式存在，这是由于它们的复制方式决定的。因此RELIK对于我们而言是一个惊喜。” Katzourakis博士认为，在实验室复制这些病毒将帮助科学家了解HIV的起源。 译自：physorg.com
部分英文原文：
Published online before print March 23, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0700471104
Evolution
Discovery and analysis of the first endogenous lentivirus
( phylogeny | retrovirus | ERV | rabbit )
Aris Katzourakis *, Michael Tristem , Oliver G. Pybus *, and Robert J. Gifford
*Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom; Division of Biology, Imperial College London, Silwood Park, Ascot, Berkshire SL5 7PY, United Kingdom; and Division of Infectious Diseases, Stanford University, Stanford, CA 94305
Edited by John M. Coffin, Tufts University School of Medicine, Boston, MA, and approved February 13, 2007 (received for review January 17, 2007)
The lentiviruses are associated with a wide range of chronic diseases in mammals. These include immunodeficiencies (such as HIV/AIDS in humans), malignancies, and lymphatic and neurological disorders in primates, felids, and a variety of wild and domesticated ungulates. Evolutionary analyses of the genomic sequences of modern-day lentiviruses have suggested a relatively recent date for their emergence, but the failure to identify any endogenous, vertically transmitted examples has meant that their longer term evolutionary history and origin remain unknown. Here we report the discovery and characterization of retroviral sequences belonging to a new lentiviral subgroup from the European rabbit (Oryctolagus cuniculus). These viruses, the first endogenous examples described, are >7 million years old and thus provide the first evidence for an ancient origin of the lentiviruses. Despite being ancient, this subgroup contains many of the features found in present-day lentiviruses, such as the presence of tat and rev genes, thus also indicating an ancient origin for the complex regulation of lentivirus gene expression. Although the virus we describe is defective, reconstruction of an infectious progenitor could provide novel insights into lentivirus biology and host interactions.
