Expert Opinion: Dr. Louis Flamand calls for screening of transplant organs and cells for ciHHV-6 status

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Expert Opinion: Dr. Louis Flamand calls for screening of transplant organs and cells for ciHHV-6 status

Dr. Flamand, a professor and molecular virologist at  Université Laval in Quebec city, has written an editorial calling for screening of organ donors for ciHHV-6 status and careful monitoring of recipients of ciHHV-6 donor tissues for signs of active HHV-6 infection and HHV-6 antigen-induced immune rejection. Flamand also questions whether solid organs and stem cells derived from persons with ciHHV-6 should be used in transplantation.

Flamand argues that organs from a ciHHV6+ donor could trigger immunologic attacks from the recipient’s immune system, even in the absence of viral replication and called for questions whether ciHHV-6 cells and organs should be used in transplantation.

Flamand has been engaged in the field of HHV-6 for over two decades and published the first in vivo evidence that ciHHV-6 could activate from it integrated (Gravel 2013). His editorial accompanied a report by Endo et al that ciHHV-6A virus reactivated in a severely immunocompromised infant. Flamand concludes that although HHV-6 genome integration within host telomeres was initially considered an “oddity” it is now “recognized as part of a bona fide viral life cycle.”

Flamand cautions that the biological consequences of HHV-6 integration within the telomeric region is an understudied research area, and the long-term proliferative potential of ciHHV-6 stem cells remains to be defined. Flamand notes that ciHHV-6 status can easily be identified by testing hair follicles or nail clippings by PCR.

Note from the HHV-6 Foundation on HHV-6 testing:

CiHHV-6 status can easily be determined by a qPCR on whole blood because ciHHV-6+ individuals will have >log5.5 DNA copies/ml. The University of Washington has a new ciHHV-6 blood test that measures the ratio of HHV-6 genomes to cells in a whole blood sample, using digital droplet PCR. In addition, two other commercial labs in the US have whole blood tests that can be used to identify ciHHV-6 status: Coppe Labs and ViracorIBT #6516. Plasma and serum DNA testing cannot reliably determine ciHHV-6.

Viral load is not very useful in determining viral reactivation in individuals with ciHHV-6 or a ciHHV-6 organ, because there is a high background level of DNA from lysed cells. So physicians must use clinical judgment to determine if the HHV-6 is active. The only assay that can reveal if the virus is replicating is one that measures mRNA and this assay is only performed on a research basis at a handful of research centers. One commercial laboratory in the US, Coppe Labs, has recently developed a mRNA Reverse Transciption PCR assay for HHV-6.

For more information, read the full article.