Distinct expression patterns of HCMV-encoded microRNAs and viral transcripts in solid organ transplant recipients

Human cytomegalovirus (HCMV) encodes multiple microRNAs that modulate viral replication, immune evasion, and latency. Among them, miR-UL112-3p, miR-UL22A-3p, and miR-US25-1-3p have been implicated in regulating host antiviral responses and viral persistence. This study evaluated the expression of three HCMV-encoded miRNAs and their corresponding viral transcripts in solid organ transplant recipients with plasma HCMV DNA loads > 10,000 copies/mL or no detectable plasma HCMV DNA, compared with healthy controls. Thirty solid organ transplant recipients with plasma HCMV DNA loads > 10,000 copies/mL (active group), 30 recipients with no detectable plasma HCMV DNA (inactive group), and 30 healthy controls were enrolled. HCMV DNA was quantified by TaqMan real-time PCR, and expression of UL112 , UL22A , US25 , miR-UL112-3p, miR-UL22A-3p, and miR-US25-1-3p was assessed by SYBR Green real-time RT-PCR. The expression levels of HCMV UL112, UL22A, and US25 transcripts and their corresponding miRNAs were evaluated in blood samples using quantitative real-time PCR. UL112, UL22A, and US25 transcript expression was higher in recipients with plasma HCMV DNA loads > 10,000 copies/mL than in recipients with no detectable plasma HCMV DNA and healthy controls. miR-UL112-3p was also elevated in active infection. Spearman correlation analysis demonstrated a moderate inverse association between UL112 mRNA and miR-UL112-3p in the inactive HCMV group (ρ = −0.46, P = 0.009), whereas no significant association was observed in the active group (ρ = 0.129, P = 0.49). UL22A and miR-UL22A-3p were not significantly correlated in either group. In contrast, US25 mRNA and miR-US25-1-3p showed strong positive correlations in both inactive (ρ = 0.92, P < 0.0001) and active HCMV infection (ρ = 0.90, P < 0.0001). HCMV-encoded miRNAs and their corresponding viral transcripts exhibit locus-specific relationships that differ between groups defined by plasma HCMV DNA status. The inverse association between UL112 and miR-UL112-3p in inactive infection, absence of correlation for UL22A /miR-UL22A-3p, and strong concordance between US25 and miR-US25-1-3p indicate that viral miRNA-transcript relationships are not uniform across HCMV loci.