The goal of this clinical trial is to evaluate the efficacy and safety of Multi-Virus Specific T cells (LB-DTK-MV) to treat patients diagnosed with antiviral-resistant CMV, BKV, or EBV infection or associated diseases after anticancer therapy or allogeneic hematopoietic stem cell transplantation (allo-HSCT). The main questions it aims to answer are:
* What is the maximum tolerated dose of LB-DTK-MV based on dose-limiting toxicity?
* Does the number of CMV, BKV, or EBV virus viral load decrease within 7 or 14 days after the second infusion of LB-DTK-MV?
* Do treatment emergent adverse events occur after the second infusion?
Participants will:
* Receive a single intravenous infusion of LB-DTK-MV during the baseline visit (low dose: 1x10\^7/m\^2; high dose: 2x10\^7/m\^2).
* Receive the second infusion of LB-DTK-MV intravenously at the same dose 14 days after the first infusion.
* Attend weekly follow-up visits at the clinic for 6 months after the first dose.