B354 - Asymptomatic Seroconversion in the High-Risk Group for Cytomegalovirus After Living Donor Kidney Transplantation

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Author Block: S. Yamanaga¹, R. Masui¹, Y. Hidaka¹, S. Horino¹, M. Toyoda², Y. Miyabe², C. Kawabata², Y. Yamamoto³, Y. Watanabe³, A. Inadome³, H. Yokomizo¹, ¹Surgery, Japanese Red Cross Kumamoto Hospital, Kumamoto, Japan, ²Nephrology, Japanese Red Cross Kumamoto Hospital, Kumamoto, Japan, ³Urology, Japanese Red Cross Kumamoto Hospital, Kumamoto, Japan
*Purpose: The cytomegalovirus (CMV) IgG serostatus of donors (D) and recipients (R) prior to kidney transplantation is an important determinant of post-transplant CMV infection risk. Among high-risk (D+/R-) recipients, most develop CMV disease, whereas some undergo spontaneous seroconversion without symptoms. This study aimed to explore factors associated with asymptomatic CMV seroconversion in the high-risk group after living donor kidney transplantation.
*Methods: We retrospectively analyzed 280 patients who underwent living donor kidney transplantation at our institution between January 2011 and March 2025. Based on pre-transplant CMV IgG serostatus, patients were classified into three groups: D+/R- (high risk), R+ (intermediate risk), and D-/R- (low risk). Factors related to asymptomatic seroconversion were further examined in the D+/R- group. CMV infection was defined as CMV antigenemia ≥1 positive cell or CMV DNA ≥100 copies/mL, and CMV disease as infection accompanied by clinical symptoms. Prophylactic therapy was administered to high-risk recipients and/or those receiving antithymocyte globulin, using valganciclovir until 2024 and letermovir from 2025 onward.
*Results: The distribution of risk groups was D+/R-: n=28, R+: n=244, and D-/R-: n=8. The D+/R- group was significantly younger than the R+ group. Prophylactic therapy was administered to a small proportion of recipients (17.9% vs 0.4% vs 0%, p<0.001). The incidence of CMV disease was significantly higher in the D+/R- group (46.4% vs 2.5% vs 0%, p<0.001), as was the rate of organ involvement (17.9% vs 1.2% vs 0%, p<0.001); all cases achieved remission. No significant differences were observed among groups in the incidence of acute rejection (7.8% vs 7.1% vs 0%, p=0.711) or 5-year graft survival (91.2% vs 93.7% vs 100%, p=0.225). In the high-risk group, the overall seroconversion rate was 71.4% (20/28), of which 25% (7/28) were asymptomatic. Among these asymptomatic recipients, five received preemptive therapy for CMV infection. Female gender was significantly more frequent in the asymptomatic group than in the symptomatic group (71.4% vs 15.4%, p=0.022).
*Conclusions: Approximately half of D+/R- recipients developed CMV disease, while one-fourth acquired CMV antibodies asymptomatically. Female gender was associated with asymptomatic seroconversion. The aggressive prophylactic approach may further improve graft outcomes, and accumulation of additional evidence is warranted to clarify the mechanisms underlying CMV-specific immune asymptomatic acquisition.