Early BK Polyomavirus–Specific Immunity and Viral Clearance

Résumé fourni par la source

Introduction BK polyomavirus (BKPyV) replication remains a frequent complication after kidney transplantation. The clinical relevance of assessing BKPyV-specific cellular immunity at the time of first detectable viremia remains incompletely defined. Methods We retrospectively studied 50 kidney transplant recipients with a first episode of BKPyV DNAemia who underwent BKPyV-specific IFN-γ ELISPOT shortly after the first positive plasma PCR. Responses directed against structural (VP1–VP3) and regulatory (large T and small t) antigens were quantified. The primary endpoint was time from ELISPOT to viral clearance. Secondary endpoints included viral clearance within 90 days, biopsy-proven BKPyV-associated nephropathy (BKPyVAN), immunosuppression reduction, and kidney function outcomes. Results Structural BKPyV-specific ELISPOT responses showed marked interindividual variability and correlated weakly with viral burden. Thirty-seven patients (74%) achieved viral clearance. Higher structural responses were independently associated with faster viral clearance (adjusted hazard ratio [aHR] per 100 spot-forming cells [SFC], 1.28; 95% confidence interval [CI], 1.15–1.42; p<0.0001), a lower incidence of biopsy-proven BKPyVAN, and a reduced need for advanced immunosuppression reduction (adjusted odds ratio [aOR] per 100 SFC, 0.34; 95% CI, 0.14–0.83; p=0.018). Responses directed against regulatory antigens showed weaker and less consistent associations with outcomes. Conclusions Early BKPyV-specific cellular immune responses measured by IFN-γ ELISPOT were consistently associated with viral clearance kinetics and clinically relevant outcomes after kidney transplantation. Structural antigen-specific responses may provide complementary information regarding antiviral immune competence and support further evaluation of immune-stratified management strategies. These findings should be considered hypothesis-generating and require prospective multicenter validation.

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