Will Bhupesh Prusty's HHV-6 breakthrough renew interest in the endogenous retrovirus HERV-K18?
HERV-K and HERV-W transcriptional activity in Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome
Abstract
Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFSMS) is an incapacitating chronic disease that dramatically compromise the life quality. The CFS/ME pathogenesis is multifactorial, and it is believed that immunological, metabolic and environmental factors play a role. It is well documented an increased activity of Human endogenous retroviruses (HERVs) from different families in autoimmune and neurological diseases, making these elements good candidates for biomarkers or even triggers for such diseases. Here the expression of Endogenous retroviruses K and W (HERVK and HERVW) was determined in blood from moderately and severely affected ME/CFS patients. HERVK was overexpressed only in moderately affected individuals and HERVW showed no difference. This is the first report about HERVK differential expression in moderate ME/CFS.
HHV-6A infection induces expression of HERV-K18-encoded superantigen
Albert K. Taia, Janos Lukab, Dharam Ablashic, Brigitte T. Huber
published online 08 June 2009.
Abstract
Background
The human endogenous retrovirus K-18 (HERV-K18) encodes a
superantigen that causes deregulation of the immune system. This
provirus is transcriptionally silent, but can be induced by Epstein–Barr
virus (EBV) infection and IFN-α treatment.
Objectives
Since the herpesvirus EBV induces HERV-K18 expression in human B
cells, it was of interest to determine if other herpesviruses would have
similar HERV-K18 transactivation properties. Human herpesvirus
(HHV)-6A, a neurotropic virus associated with multiple sclerosis, was a
logical candidate for these studies.
Study design
HSB2 cells (HHV-6-negative control), HSB2-ML cells (containing latent
HHV-6A genome) and HSB2/HHV-6A cells (HSB-2 cells productively infected
with HHV-6A) were compared for their level of HERV-K18 transcription,
using quantitative RT-PCR.
Results
Latently infected HSB2-ML cells showed a significant increase in
HERV-K18 RNA compared to the control cells. HERV-K18 expression was even
greater in HSB2 cells productively infected with HHV-6A for 78h.
Conclusion
These results imply that HHV-6A, either in latent form or during
acute infection, directly transactivates HERV-K18. This HERV-K18
induction may be mediated through IFN-α that is produced by the
HHV-6A-infected cells. The functional implications of superantigen
expression are discussed.