CMV-DNA Level in zero-hour kidney tissue is associated with Risk of post-transplant CMV Infection in D+/R− Living Donor Kidney Transplantation

Introduction: Primary cytomegalovirus (CMV) infection risk is highest in kidney transplantation (KTx) from CMV-seropositive donors to CMV-seronegative recipients (D+/R−). However, approximately 30% of such recipients do not develop primary CMV infection, suggesting heterogeneity in infection risk. Reliable biomarkers for predicting CMV infection risk in CMV D+/R− KTx remain limited. This study aimed to evaluate whether CMV-DNA in donor kidney tissue is detectable and is associated with the development and severity of post-transplant CMV infection using digital droplet PCR (ddPCR).
Methods: We retrospectively analyzed 24 CMV D+/R− adult recipients who underwent living donor KTx between 2020 and 2024. Among them, 6 cases were excluded with 0-hour kidney tissue at the time of transplant has not been stored. All 18 recipients were routinely monitored for CMV using quantitative PCR in blood after transplantation according to institutional protocols consistent with current guidelines. Patients were classified into three groups according to post-transplant CMV infection presentation: no infection (n=6), CMV DNAemia (n=5), and probable CMV disease (n=7). Frozen 0-hour biopsy specimens obtained at transplantation were analyzed for CMV-DNA using ddPCR, and viral load was quantified as copies per μg DNA. The association was evaluated between CMV-DNA in the kidney tissue and CMV infection outcome.
Results: CMV transcription or protein expression was undetectable by RT-PCR or immunofluorescence staining, suggesting viral activity below the detection limit. In contrast, CMV-DNA was detectable in donor kidney tissue using ddPCR in 12 of 18 cases (66.7%). CMV-DNA levels measured by ddPCR in zero-hour biopsy specimens were associated with the development and severity of primary CMV infection after KTx. Donor kidney CMV-DNA levels showed a stepwise increase across the three groups (0, 5.03, and 7.05 copies/μg DNA, respectively; p<0.0001, Kruskal–Wallis test). Recipients receiving donor kidneys with higher CMV-DNA levels were more likely to develop CMV DNAemia or probable CMV disease during follow-up. These findings suggest that donor kidney CMV-DNA burden reflects a potential CMV reservoir within the graft.
Conclusion: CMV-DNA was successfully detected in frozen donor kidney tissue using ddPCR. Detection of CMV-DNA in seropositive living donor kidney tissue may help stratify the risk of post-transplant CMV infection in seronegative recipients. These findings suggested that presence and amount of CMV-DNA in living-donor kidney therefore predict primary CMV infection in CMV D+/R− kidney transplant recipients and support more individualized CMV management after KTx.