[Clinical Analysis of Torque Teno Virus Infection after Hematopoietic Stem Cell Transplantation in Children]

To investigate the incidence, clinical characteristics, and complications of Torque teno virus (TTV) in children after hematopoietic stem cell transplantation (HSCT).

A total of 40 children with hematological diseases who underwent HSCT were selected, and metagenomic next-generation sequencing (mNGS) technology was used to detect the gene sequences of pathogenic microorganisms in the blood. Combined with clinical data, the characteristics of TTV infection were analyzed.

Among the 40 pediatric patients post-HSCT, the TTV positive rate was 42.5% (17/40). There were no statistically significant differences between the TTV-positive group and the TTV-negative group in sex, age, white blood cell count(WBC), red blood cell count(RBC), hemoglobin, platelet count, neutrophil count, lymphocyte count, and high-sensitivity C-reactive protein (all P >0.05). The incidence of TTV infection was significantly higher in children who underwent haploidentical HSCT and in those with bone marrow stem cells (BMSC) as the transplant source (P <0.05). However, there were no significant differences in the TTV infection rate among patients with different disease types, different HLA matching statuses, or different engraftment times of neutrophils and platelets (all P >0.05). Among 17 children infected with TTV, 13(76.5%) had co-infections with other viruses, mainly including cytomegalovirus (58.8%, 10/17), human polyomavirus (41.2%, 7/17), and Epstein-Barr virus (17.6%, 3/17). In children with TTV infection, the most common complications were sepsis (82.4%), graft-versus-host disease (GVHD) (70.6%), pulmonary infection (41.2%), and hemorrhagic cystitis (17.6%). The incidence of GVHD in the TTV-positive group was significantly higher than that in the TTV-negative group (P <0.05).

TTV infection is common in children undergoing HSCT, and it is prone to be complicated with cytomegalovirus infection and GVHD, which has an important influence on the clinical outcomes.