New research says that up to half a million people in Britain carry a particular form of herpesvirus 6 inherited from a parent.
The study from the world-renowned Department of Genetics at the University of Leicester, is funded principally by the Medical Research Council (MRC), and published in the journal Nucleic Acids Research.
The research led by Dr Nicola Royle, Senior Lecturer in Genetics, has identified a mechanism by which the inherited herpesvirus 6 can escape from the chromosome and may be able to reactivate under certain conditions.
The research in Dr Royle's laboratory focuses on telomeres, structures at the ends of chromosomes that have a protective role. When a telomere becomes short or is damaged it can trigger cellular senescence or result in genetic changes; consequently telomeres have roles in ageing and cancer. The inherited herpesvirus 6 (CI-HHV-6) is found in a telomere and so the questions Dr Royle has been addressing are: what is the virus doing there and does it affect telomere function?
There are many human herpesviruses and most can enter latency following infection, during which they persist in a small subset of cells lifelong. For example, the primary infection of HHV-3 causes chickenpox in children but following latency it can reactivate and cause shingles.
The 1% of us that inherit CI-HHV-6 in a telomere have a high copy number of this virus (one copy per cell of the whole body) but it is not known if this is a form of latency.
The Leicester study found that in people with CI-HHV-6, the viral genome is intact (has all of the genes required to reactivate). They showed that the telomere with the virus is unstable - prone to sudden deletions resulting in a very short telomere that may cause further instability. This facilitates release of the viral genome. Dr Royle proposes that the virus uses normal telomere processes to escape from the chromosome and that this may represents the first step towards viral reactivation.