Cytomegalovirus-RNA Accurately Identifies Clinically Significant Infection Needing Preemptive Therapy in Liver Transplanted Children: A Proof-of-Concept Study

Abstract

Preemptive therapy (PET) is safe and effective in controlling Cytomegalovirus (CMV) infection after pediatric liver transplantation (LT) and allows to observe the kinetics of quantitative CMV-DNA viral load till it reaches the treatment thresholds. While early detection of low-to-moderate CMV-DNA levels may not indicate active viral replication, awaiting the viral load to exceed the treatment threshold may lead to viremic breakthroughs and CMV disease. We assessed the capacity of quantitative CMV-RNA (UL21.5 mRNA) to identify active viral replication and its accuracy in identifying clinically significant CMV infection (csCMVi) needing PET in LT children. One-hundred and forty-four comparative quantitative CMV-RNA and CMV-DNA determinations were obtained from 12 children followed prospectically for 6 months after LT. Of 52 CMV-DNA-positive specimens, 17 (32%) were also CMV-RNA-positive, while CMV-RNA was undetectable in CMV-DNA-negative specimens. All children with csCMVi had early detectable CMV-RNA, peaking simultaneously to CMV-DNA (median CMV-DNA: 65 906 cp/mL; median CMV-RNA: 767 cp/mL); conversely, none of those with persistently low DNAemia proved CMV-RNA-positive. In this first pilot study, CMV-RNA had 100% sensitivity and specificity in identifying children needing PET after pediatric LT. The early detection of CMV-RNA marks significant CMV infection/reactivation, thus allowing to avoid unnecessary antiviral treatment.

Keywords: Cytomegalovirus; epidemiology; immune system; infection; latent infection; pathogenesis; transplantation; virus classification.

Figure 1

(A) Scatter plot of the Log CMV‐DNA according to the concomitant CMV‐RNA result. Red dots are specimens from patients in the “clinically significant CMV infection” group, and green dots from patients in the “Low viremia” group. (B) and (C) Kinetics of the Log CMV‐DNA (squares, solid line) and CMV‐RNA (triangles, dotted line) expressed as mean ± standard deviation in “Low viremia” and “clinically significant CMV infection” groups. The gray area represents the threshold adopted for preemptive therapy. csCMVi, clinically significant CMV infection; LT, liver transplantation.

Figure 2

Flow chart displaying the CMV‐related outcome of the 12 patients included. *Children aging ≤ 18 months at liver transplant, in whom CMV‐IgG positivity due to maternal antibodies cannot be excluded. D, donor CMV‐IgG; LT, liver transplantation; R, recipient IgG.

Figure 3

Monitoring of CMV viremia in 9 CMV‐DNA‐positive children after liver transplantation. Patients 1, 3, 4, and 7 display clinically significant CMV infection (Patient 1 = CMV disease; Patients 3, 4, and 7 = high‐viremic infection treated with preemptive therapy); patients 2, 5, 6, 11, and 12 maintained low viremia and did not require preemptive therapy. Log CMV‐DNA (squares, solid line) and CMV‐RNA (triangles, dotted line) are shown; arrowheads represent the GCV treatment; CMV T‐SPOT results at 0, +2, +4 weeks, and +6 months are considered as positive (+) or negative (−) with regard to the threshold of ≥ 30 or ≥ 10 spots/200 000 cells for pp65 or IE‐1, respectively, while specimen failing the positive control are indetermined (i); the gray area represents the threshold adopted for preemptive therapy; *diagnosis of CMV disease (CMV‐related colitis). LT, liver transplantation.