Transactivation of Human Endogenous Retroviruses by Viruses

Abstract

Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections that are part the human genome and are normally silenced through epigenetic mechanisms. However, HERVs can be induced by various host and environmental factors, including viral infection, and transcriptionally active HERVs have been implicated in various physiological processes. In this review, we summarize mounting evidence of transactivation of HERVs by a wide range of DNA and RNA viruses. Though a mechanistic understanding of this phenomenon and the biological implications are still largely missing, the link between exogenous and endogenous viruses is intriguing. Considering the increasing recognition of the role of viral infections in disease, understanding these interactions provides novel insights into human health.

Keywords: endogenous retroviruses; transactivation; viral infection.

Figure 1

Summary of HERV activation by viruses. HERVs that are activated by the indicated viruses and virus families are listed along with the types of samples where HERVs are detected. The post-viral diseases that are associated with viruses are also highlighted.

Figure 2

HERV activation by HSV-1. Viral proteins and host transcription factors that are involved in the activation of MSRV (a), HERV-W (b) and HERV-K (c) in context of HSV-1 infection.

Figure 3

Activation of HERVs by EBV. Expression of MSRV, Syn-1 and HERV-K18 are regulated by viral and host factors that are expressed or activated during EBV infection.

Figure 4

Expression of ERVs during IAV infection. Cellular cues and factors that are modulated during IAV infection regulate expression of ERVV-1, ERVV-2 and HERV-W.