The Impact of Cytomegalovirus Reactivation on Cytomegalovirus-Specific Immune Reconstitution in Hematopoietic Stem Cell Transplant Recipients Receiving Letermovir Prophylaxis

Cen Jiang; Lilan Jin; Luxiang Wang; Yanying Gu; Xiaoxia Hu; Gang Cai

doi:10.1093/ofid/ofag160

The Impact of Cytomegalovirus Reactivation on Cytomegalovirus-Specific Immune Reconstitution in Hematopoietic Stem Cell Transplant Recipients Receiving Letermovir Prophylaxis

Open Forum Infect Dis. 2026 Mar 26;13(4):ofag160. doi: 10.1093/ofid/ofag160. eCollection 2026 Apr.

Authors

Cen Jiang¹, Lilan Jin¹, Luxiang Wang², Yanying Gu¹, Xiaoxia Hu², Gang Cai¹

Affiliations

¹ Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University Medical School, Shanghai, PR China.
² Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, PR China.

Abstract

Background: Cytomegalovirus (CMV) remains the most common viral infection after hematopoietic stem cell transplantation (HSCT). The clinical significance of different CMV DNA forms remains unclear, particularly regarding CMV-specific immune reconstitution.

Methods: A total of 76 HSCT recipients were enrolled. A quantitative DNase I-resistant CMV-DNA assay was performed to distinguish infectious from noninfectious CMV DNA. Based on DNase treatment results, patients were divided into 3 groups: (1) negative DNAemia (ND, n = 25): with no detectable CMV DNA; (2) DNase I-sensitive DNAemia (DSD, n = 26): with only DNase I-sensitive CMV DNA detected; (3) DNase I-resistant DNAemia (DRD, n = 25): with at least one episode of DNase I-resistant CMV DNAemia within 100 days posttransplant. CMV-specific T-cell responses were evaluated by multiparameter flow cytometry, and cytokine polyfunctionality was quantified using Combinatorial Polyfunctionality Analysis of Antigen-Specific T-cell Subsets analysis.

Results: Early CMV reactivation was associated with stronger CD8⁺ than CD4⁺ T-cell responses. DNase I-resistant DNAemia patients exhibited significantly enhanced polyfunctional CD8⁺ T-cell responses compared with ND patients, while DSD patients did not. Among patients with detectable CMV DNA, stronger CD8⁺ T-cell responses correlated with higher peak viral loads and greater viral shedding. Elevated CMV-specific CD4⁺ T-cell responses were associated with higher peak CMV-DNA loads and reduced risk of CMV reactivation after day 100 posttransplant. In multivariable analysis, acute graft versus host disease was an independent risk factor for CMV reactivation.

Conclusions: Cytomegalovirus-specific immune reconstitution appears delayed in DSD compared with DRD patients, potentially reflecting limited exposure to replication-competent virus. Assessment of CMV-specific T-cell polyfunctionality may help identify HSCT recipients at increased risk for late CMV reactivation.

Keywords: CMV-specific immunity; cytomegalovirus; immune reconstitution; stem cell transplantation.