The Telomeric Repeats of Human Herpesvirus 6A (HHV-6A) Are Required for Efficient Virus Integration

PLoS Pathog. 2016 May 31;12(5):e1005666. doi: 10.1371/journal.ppat.1005666. eCollection 2016 May.

Abstract

Human herpesvirus 6A (HHV-6A) and 6B (HHV-6B) are ubiquitous betaherpesviruses that infects humans within the first years of life and establishes latency in various cell types. Both viruses can integrate their genomes into telomeres of host chromosomes in latently infected cells. The molecular mechanism of viral integration remains elusive. Intriguingly, HHV-6A, HHV-6B and several other herpesviruses harbor arrays of telomeric repeats (TMR) identical to human telomere sequences at the ends of their genomes. The HHV-6A and HHV-6B genomes harbor two TMR arrays, the perfect TMR (pTMR) and the imperfect TMR (impTMR). To determine if the TMR are involved in virus integration, we deleted both pTMR and impTMR in the HHV-6A genome. Upon reconstitution, the TMR mutant virus replicated comparable to wild type (wt) virus, indicating that the TMR are not essential for HHV-6A replication. To assess the integration properties of the recombinant viruses, we established an in vitro integration system that allows assessment of integration efficiency and genome maintenance in latently infected cells. Integration of HHV-6A was severely impaired in the absence of the TMR and the virus genome was lost rapidly, suggesting that integration is crucial for the maintenance of the virus genome. Individual deletion of the pTMR and impTMR revealed that the pTMR play the major role in HHV-6A integration, whereas the impTMR only make a minor contribution, allowing us to establish a model for HHV-6A integration. Taken together, our data shows that the HHV-6A TMR are dispensable for virus replication, but are crucial for integration and maintenance of the virus genome in latently infected cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA, Viral / genetics
  • Herpesvirus 6, Human / genetics*
  • Humans
  • Polymerase Chain Reaction
  • Roseolovirus Infections / genetics*
  • Telomere / genetics*
  • Virus Integration / genetics*
  • Virus Replication / genetics

Substances

  • DNA, Viral

Grants and funding

This study was supported by the grant KA 3492/1-1 from the Deutsche Forschungsgemeinschaft (DFG, German Science Foundation, http://www.dfg.de). The Deutsche Forschungsgemeinschaft is a governmental funding agency comparable to the National Science Foundation in the USA. In addition, further support was provided by the European Research Council grant StG-677673 (https://erc.europa.eu). European Research Council is a Europe wide governmental funding agency with a funding scheme comparable to the NIH in the USA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.