Abstract
Human cytomegalovirus (HCMV) is the most frequent cause of opportunistic viral infection following transplantation. Viral factors of potential clinical importance include the selection of mutants resistant to antiviral drugs and the occurrence of infections involving multiple HCMV strains. These factors are typically addressed by analyzing relevant HCMV genes by PCR and Sanger sequencing, which involves independent assays of limited sensitivity. To assess the dynamics of viral populations with high sensitivity, we applied high-throughput sequencing coupled with HCMV-adapted target enrichment to samples collected longitudinally from 11 transplant recipients (solid organ, n = 9, and allogeneic hematopoietic stem cell, n = 2). Only the latter presented multiple-strain infections. Four cases presented resistance mutations (n = 6), two (A594V and L595S) at high (100%) and four (V715M, V781I, A809V, and T838A) at low (<25%) frequency. One allogeneic hematopoietic stem cell transplant recipient presented up to four resistance mutations, each at low frequency. The use of high-throughput sequencing to monitor mutations and strain composition in people at risk of HCMV disease is of potential value in helping clinicians implement the most appropriate therapy.
Highlights
Despite continuous advances in diagnostics and therapy, human cytomegalovirus (HCMV) remains the most frequent opportunistic viral infection following transplantation, contributing significantly to patient morbidity, and mortality (Boeckh and Ljungman, 2009)
Resistance mutations can be screened in the genes responsible for antiviral drug activity, whereas multiple-strain infections may be detected by genotyping hypervariable genes
Plasma (n = 42) and whole blood (n = 20) samples from confirmed HCMV-infected transplant recipients were collected longitudinally during episodes of viremia. They were collected at times following transplantation or after HCMV reactivation ranging from 16 to 336 days, and had viral loads ranging from 6.94 × 102 to 8.13 × 106 HCMV international units per ml (IU/ml) of plasma
Summary
Despite continuous advances in diagnostics and therapy, human cytomegalovirus (HCMV) remains the most frequent opportunistic viral infection following transplantation, contributing significantly to patient morbidity, and mortality (Boeckh and Ljungman, 2009). Resistance mutations can be screened in the genes responsible for antiviral drug activity (typically UL54 encoding the viral DNA polymerase, and UL97 encoding a phosphotransferase), whereas multiple-strain infections may be detected by genotyping hypervariable genes (commonly UL73 encoding glycoprotein N [gN], UL74 [gO], and UL55 [gB]). This strategy involves an independent assay for each gene analyzed, and its sensitivity is generally limited to the detection of subpopulations exceeding 20% of the total viral population (Schuurman et al, 1999; Sahoo et al, 2013)
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