Transplant Testing for Human Herpesviruses
Coppe Laboratories’ scientists have a long history in the study and diagnosis of viral infections in transplant patients. Drs. Knox and Carrigan were among the first scientists to correlate symptoms of pneumonitis, encephalitis, and graft failure in bone marrow transplant recipients with reactivation of HHV-6.
Until now, testing for HHV-6 has lacked the specificity for differentiating between latent and active infection. Coppe Laboratories performs reverse transcription polymerase chain reaction (RT-PCR) which is a a sensitive and powerful tool for analyzing active, replicating virus.
Coppe Laboratories is currently the only reference laboratory performing comprehensive testing for chromosomally integrated HHV-6 (ciHHV-6) on blood, hair follicle and nail clippings.
We are also currently the only reference laboratory providing immunohistochemical staining of tissues to denote active HHV-6 infection.
Chromosomally Integrated HHV-6
HHV-6 exists in a chromosomally integrated form (ciHHV-6) whereby the viral DNA resides in every somatic and germ cell in the body. Patients with ciHHV-6 have been misdiagnosed and unnecessarily treated with powerful and toxic antiviral agents based on a mistaken diagnosis of reactivated HHV-6. High persistent HHV-6 DNA levels in blood can be found in immunocompetent individuals with viral chromosomal integration. Analysis for integration is a necessary first step in distinguishing between ciHHV6 and HHV-6 reactivation.
The second necessary step for identifying HHV-6 reactivation in a ciHHV6 patient is confirmation of viral gene expression using mRNA detection. RT-PCR for mRNA can distinguish an active herpesvirus infection from a latent infection. In addition, it is difficult to evaluate response to antiviral therapy in a ciHHV-6 patient because the high level of DNA from ciHHV-6 overwhelms and masks viral DNA produced by reactivated virus. mRNA testing can be used to evaluate the efficacy of antiviral therapy in a ciHHV-6 patient.
The ciHHV-6 panel from Coppe Laboratories
ciHHV6 occurs in about 1% of the population and confounds the diagnostic interpretation of reactivated HHV-6 in solid organ and hematopoietic transplant recipients (SOT and HCT). In the case of an HCT recipient or donor who has undiagnosed ciHHV6, the evolution of chimerism due to stem cell engraftment can be misdiagnosed as HHV-6 reactivation during the early engraftment period and patients may be treated inappropriately. Conversely, in the case of pre-identified ciHHV6 HCT or SOT recipients, the high background level of DNA from integrated HHV-6 can mask HHV-6 reactivation and make it impossible to evaluate the efficacy of antiviral therapy.
The ciHHV-6 Test Panel from Coppe Laboratories can identify active infection in a ciHHV-6 individual.