Viruses and their hosts are locked in an evolutionary race where resistance to infection is acquired by the hosts while viruses develop strategies to circumvent these host defenses. Forming one arm of the host defense armory are cell autonomous restriction factors like Fv1. Originally described as protecting laboratory mice from infection by murine leukemia virus (MLV), Fv1s from some wild mice have also been found to restrict non-MLV retroviruses, suggesting an important role in the protection against viruses in nature. We surveyed the Fv1 genes of wild mice trapped in Thailand and characterized their restriction activities against a panel of retroviruses. An extra copy of the Fv1 gene, named Fv7, was found on chromosome 6 of three closely related Asian species of mice: Mus caroli, M. cervicolor, and M. cookii. The presence of flanking repeats suggested it arose by LINE-mediated retroduplication within their most recent common ancestor. A high degree of natural variation was observed in both Fv1 and Fv7 and, on top of positive selection at certain residues, insertions and deletions were present that changed the length of the reading frames. These genes exhibited a range of restriction phenotypes, with activities directed against gamma-, spuma-, and lentiviruses. It seems likely, at least in the case of M. caroli, that the observed gene duplication may expand the breadth of restriction beyond the capacity of Fv1 alone and that one or more such viruses have recently driven or continue to drive the evolution of the Fv1 and Fv7 genes.

病毒及其宿主处于进化竞赛中，宿主对感染具有抵抗力，而病毒则制定了规避这些宿主防御的策略。像Fv1这样的细胞自治限制因子形成了宿主防御军械库的一只手臂。最初被描述为保护实验室小鼠免受鼠白血病病毒（MLV）的感染，但也发现来自某些野生小鼠的Fv1会限制非MLV逆转录病毒，这表明在保护自然界中的病毒方面起着重要作用。我们调查了被困在泰国的野生小鼠的Fv1基因，并表征了它们对一组逆转录病毒的限制性活性。在三个紧密相关的亚洲小鼠物种的第6号染色体上发现了一个名为Fv7的Fv1基因的额外拷贝：亩CAROLI，中号。cervicolor和中号。cookii。侧翼重复序列的存在表明它是由LINE介导的重复复制在其最近的共同祖先中产生的。在Fv1和Fv7中均观察到高度的自然变异，并且在某些残基处的阳性选择之上，还存在插入和缺失，这些变化改变了阅读框的长度。这些基因表现出一系列限制性表型，具有针对γ-，spuma-和慢病毒的活性。至少在M的情况下似乎有可能。卡罗利，观察到的基因重复可能将限制的范围扩展到超过Fv1单独的能力，并且一种或多种此类病毒最近已驱动或继续驱动Fv1和Fv7基因的进化。