Genes 2013, 4, 573-582; doi:10.3390/genes4040573 OPEN ACCESS genes ISSN 2073-4425 www.mdpi.com/journal/genes Review Pathological and Evolutionary Implications of Retroviruses as Mobile Genetic Elements 1 2 Madeline Hayes , Mackenzie Whitesell and Mark A. Brown 3,* 1 Department of Biology, Colorado State University, 801 Oval Drive, Fort Collins, CO 80523, USA; E-Mail:
[email protected] 2 Department of Environmental and Radiological Health Sciences, Colorado State University, 801 Oval Drive, Fort Collins, CO 80523, USA; E-Mail:
[email protected] 3 Department of Clinical Sciences, Colorado State University, Colorado State University, 801 Oval Drive, Fort Collins, CO 80523, USA * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +1-970-491-5782. Received: 15 July 2013; in revised form: 27 September 2013 / Accepted: 8 October 2013 / Published: 24 October 2013 Abstract: Retroviruses, a form of mobile genetic elements, have important roles in disease and primate evolution. Exogenous retroviruses, such as human immunodeficiency virus (HIV), have significant pathological implications that have created a massive public health challenge in recent years. Endogenous retroviruses (ERVs), which are the primary focus of this review, can also be pathogenic, as well as being beneficial to a host in some cases. Furthermore, retroviruses may have played a key role in primate evolution that resulted in the incorporation of these elements into the human genome. Retroviruses are mobile genetic elements that have important roles in disease and primate evolution. We will further discuss the pathogenic potential of retroviruses, including their role in cancer biology, and will briefly summarize their evolutionary implications.