Coinfection of Human Herpesviruses 6A (HHV-6A) and HHV-6B as Demonstrated by Novel Digital Droplet PCR Assay.
http://www.ncbi.nlm.nih.gov/pubmed/24663487
Abstract
The human
herpesviruses HHV-6A and HHV-6B have been associated with various
neurologic disorders partly due to the detection of elevated viral DNA
levels in patients compared to controls. However the reported frequency
of these viruses varies widely, likely reflecting differences in PCR
methodologies used for detection. Digital droplet PCR (ddPCR) is a third
generation PCR technology that enables the absolute quantification of
target DNA molecules. Mounting evidence of the biological differences
between HHV-6A and HHV-6B has led to their recent reclassification as
separate species. As it is now especially relevant to investigate each
virus, our objectives were to first design a multiplex HHV-6A and HHV-6B
ddPCR assay and then to investigate the incidence of HHV-6A and HHV-6B
coinfection in samples from healthy donors and patients with MS, a
disease in which HHV-6 is thought to play a role. In our assessment of
healthy donors, we observed a heretofore-underappreciated high frequency
of coinfection in PBMC and serum, and found that our assay precisely
detects both HHV-6A and HHV-6B chromosomally integrated virus, which has
important implications in clinical settings. Interestingly, upon
comparing the saliva from MS patients and healthy donors, we detected a
significantly elevated frequency of coinfection in MS saliva; increased
detection of HHV-6A in MS patients is consistent with other studies
suggesting that this viral species (thought to be more neurotropic than
HHV-6B) is more prevalent among MS patients compared to healthy donors.
As the biology and disease associations between these two viral species
differ, identifying and quantifying both species of HHV-6 may provide
clinically relevant information, as well as enhance our understanding of
the roles of each in health and disease.
