To summarize and analyze the infectious characteristics of early human parvovirus B19 (HPV-B19) positive liver transplant recipients with metagenomic next-generation sequencing (mNGS) detection after transplantation and the relevant clinical experience of diagnosis and treatment.

The clinical data of 21 recipients who underwent liver transplantation in the Department of Organ Transplantation of Jiangxi Provincial People′s Hospital from June 2021 to February 2022 and were early HPV-B19 positive with mNGS detection after transplantation (postoperative days 5 to 10) were retrospectively analyzed. Quantitative polymerase chain reaction (qPCR) was used to detect the HPV-B19 in 21 recipients during the same period, and HPV-B19 DNA > 1×10³ copies/mL was considered as HPV-B19 positive. The detection results, infection status, disease characteristics, diagnosis and treatment methods of 21 recipients were summarized and analyzed. Normally distributed measurement data were compared using the paired t-test, and enumeration data were compared using the Chi-square test. P<0.05 was considered statistically significant.

Venous blood samples of all 21 recipients were detected, of which 3 were additionally examined by bronchoscopy for mNGS from bronchoalveolar lavage fluid samples due to the presence of pulmonary infection after transplantation, and the remaining 18 deep sputum samples were detected by mNGS. Seven (33.3%) of 21 recipients were positive with qPCR for HPV-B19. All recipients had varying degrees of anemia before treatment, during which the lowest hemoglobin value was (75±11) g/L. the dosage of immune drugs of 20 among the 21 recipients was reduced immediately after mNGS, and the remaining 1 case was only observed. Nine of the 21 recipients with a continuous decrease in hemoglobin levels after transplantation and were treated with blood transfusion. Four of the nine recipients were treated with intravenous immunoglobulin (IVIG) in addition to having to transfuse red blood cell suspension. CD4⁺ /CD8⁺ T cells in 21 recipients were (1.12±0.47) and (1.51±0.72) before and 1 month after treatment, respectively, and the difference was statistically significant (t=-2.106, P<0.05). CD4⁺ and CD8⁺ counts were (236±130)/μL and (212±98)/μL before treatment, and (284±252)/μL and (174±108)/μL 1 month after treatment, respectively, and the differences were not statistically significant (t=-0.779 and 1.182, all P>0.05). Hemoglobin was (108±15) and (130±15) g/L at 1 and 3 months after transplantation in 21 recipients, respectively. HPV-B19 DNA qPCR reexamination was negative at 3 months after surgery for all recipients. During follow-up until May 2022, 21 recipients showed significant improvement in anemia symptoms and did not require red blood cell transfusion or IVIG therapy.

For HPV-B19 positive recipients screened early by mNGS after liver transplantation, anemia symptoms could be effectively controlled in most recipients by giving a treatment regimen based on reducing the intensity of immunosuppression. For recipients with persistent anemia, a treatment regimen of reducing the intensity of immunosuppression combined with blood transfusion can be considered, and low-dose IVIG was effective when the effect was poor. For liver transplant recipients tested positive for HPV-B19 via qPCR, the treatment effect of reducing the intensity of immunosuppression alone can not be satisfied.