Human cytomegalovirus (HCMV) infection is one of the most common and serious complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Standard monitoring uses HCMV DNA testing, but this method may not detect the virus early enough to guide timely treatment.

This multicenter observational study will evaluate a new high-performance microRNA (miRNA) detection technology (PSTM-qPCR) for monitoring HCMV infection in allo-HSCT patients. Approximately 300 patients and their donors will be enrolled across several major transplant centers in China. Blood samples will be collected before and after transplantation to test for both HCMV-miRNA and HCMV-DNA. The study will compare the sensitivity and timing of miRNA detection with conventional DNA testing and explore whether miRNA can serve as an early biomarker of infection and related complications.

The goal is to improve early diagnosis and management of HCMV infection, reduce infection-related complications, and ultimately improve survival outcomes in patients undergoing allo-HSCT.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment for hematologic malignancies and non-malignant disorders. However, post-transplant immune suppression and delayed immune reconstitution make patients highly susceptible to opportunistic infections, among which human cytomegalovirus (HCMV) infection and reactivation are the most frequent and clinically significant. HCMV reactivation has been associated with increased non-relapse mortality, graft-versus-host disease (GVHD), marrow suppression, and organ-specific disease, significantly affecting patient outcomes.

Current standard monitoring relies on quantitative polymerase chain reaction (qPCR)-based HCMV DNA testing in peripheral blood. While this method has improved patient management, limitations remain. HCMV DNA testing may lack sufficient sensitivity to detect early viral reactivation, leading to missed opportunities for timely pre-emptive therapy. Increasing evidence suggests that HCMV-encoded microRNAs (miRNAs), which play critical roles in viral latency, replication, and immune evasion, may serve as novel biomarkers for earlier detection of HCMV activity.

This prospective, multicenter, observational cohort study will evaluate the diagnostic and predictive performance of HCMV-miRNAs using a novel high-performance detection platform, PSTM-qPCR, developed in collaboration with the National Institute of Diagnostics and Vaccine Development in Infectious Diseases at Xiamen University. PSTM-qPCR offers markedly improved sensitivity and specificity compared with conventional qPCR, with the ability to distinguish single-base differences and detect viral activity earlier.

Approximately 300 allo-HSCT recipients and their donors will be enrolled across seven transplant centers in China. Blood samples will be collected at baseline (pre-transplant) and serially post-transplant (weekly during the first 3 months, monthly through 6 months, and as clinically indicated up to 12 months). Both HCMV-miRNA and HCMV-DNA will be measured. Primary outcome measures include the diagnostic performance of HCMV-miRNA compared with HCMV-DNA for early detection of HCMV infection. Secondary outcomes include rates of HCMV infection and reactivation, HCMV-related mortality and organ disease, GVHD incidence, and overall survival.

The study aims to validate HCMV-miRNA as a reliable early biomarker for HCMV infection in allo-HSCT recipients. By establishing a sensitive and clinically applicable monitoring strategy, this research seeks to improve infection control, guide individualized antiviral therapy, and ultimately enhance survival and quality of life in transplant patients.

Inclusion Criteria:

- Patients scheduled to undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT).

Stem cell source includes peripheral blood stem cells and/or bone marrow plus peripheral blood.

Ability to understand study procedures and provide written informed consent.

Voluntary participation in the study.

Exclusion Criteria:

• Pregnant or breastfeeding women.

Children or individuals with severe cognitive impairment who cannot comply with blood sample collection.

Patients with severe comorbidities or other medical conditions judged by the investigator to significantly interfere with study participation or follow-up.

Withdrawal of informed consent during the study.

Clinical background or history that may introduce significant confounding effects, or when additional sampling frequency is deemed to pose undue risk to the participant.

This study will include patients scheduled to undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT) at participating transplant centers in China, along with their corresponding stem cell donors. Eligible recipients are patients with hematologic malignancies or related disorders who meet transplant indications. Stem cell sources include peripheral blood stem cells and/or bone marrow plus peripheral blood. All participants must voluntarily join the study and provide written informed consent.

Individual participant data will not be shared due to privacy concerns and ethical restrictions. Only de-identified, aggregated results will be published in scientific journals or presented at academic conferences.