Laboratory mice carry three host range groups of gammaretroviruses all of which are linked to leukemia induction. Although polytropic mouse leukemia viruses (P-MLVs) are generally recognized as the proximate cause of MLV-induced leukemias in laboratory mice, wild mice that carry only endogenous P-MLVs do not produce infectious virus and are not prone to disease; these mice carry the permissive XPR1 retroviral receptor and an attenuated variant of the retroviral restriction factor, APOBEC3. In contrast, Eurasian mice carrying ecotropic and xenotropic MLVs have evolved multiple restrictive XPR1 variants, other factors that interfere with MLV entry, and more effectively antiviral variants of APOBEC3. These different antiviral restrictions in Mus musculus subspecies suggest that the different virus types found in these natural populations may pose different but largely uncharacterized survival risks in their host subspecies.

实验室小鼠携带三组宿主范围的伽马逆转录病毒，所有这些组都与白血病诱导有关。虽然多嗜性小鼠白血病病毒（P-MLVs）被普遍认为是实验室小鼠发生MLV诱发白血病的近因，但仅携带内源性P-MLVs的野生小鼠不产生传染性病毒，不易患病；这些小鼠携带允许的 XPR1 逆转录病毒受体和逆转录病毒限制因子的减毒变体 APOBEC3。相比之下，携带嗜嗜性和异性 MLV 的欧亚小鼠已经进化出多种限制性 XPR1 变体、其他干扰 MLV 进入的因素，以及更有效的 APOBEC3 抗病毒变体。Mus musculus 中这些不同的抗病毒限制 亚种表明，在这些自然种群中发现的不同病毒类型可能对其宿主亚种造成不同但在很大程度上未表征的生存风险。