Identification of BK Virus Genotypes in Recipients of Renal Transplant in Vietnam

Objectives: This study aims to investigate the prevalence and distribution of BK polyomavirus (BKV) genotypes in recipients of renal transplant in Vietnam.

Methods: One hundred six patients who underwent renal transplantation were included in this study. These patients were from the Department of Nephrology, Military Hospital 103, Vietnam Military Medical University. Quantification and genotyping of the BK virus was performed using in-house molecular methods from urine and plasma samples.

Results: BKV infection was detected in 82 patients (77.4%), including 58 patients who had the presence of both BK viremia and BK viruria, and 24 patients (22.60%) with BKV positive findings in the urine alone. Particularly, 16 patients (15.09%) had high BK viremia >10⁴ copies/mL and 20 patients (18.9%) had BK viruria >10⁷ copies/mL. BK virus nephropathy (BKVN) was confirmed in 6 patients (5.66%) by immunohistochemistry examination. Genotyping of BKV was performed successfully in 50 out of the 82 patients, with 36 out of 50 (72%) belonging to the BKV-I subtype and 14 out of 50 (28%) belonging to the BKV-IV subtype; no cases of genotypes II or III were observed. Using phylogenetic analysis of the subgroups, the BKV-I/b-1 subtype was found the predominant subgroup (100%), whereas BKV-IV included 21.43% of IV/a-1, 6.67% of IV/a-2, and 50% of IV/c-1, respectively. There remain 3 cases of BKV-IV (21.43%) that could not be categorized into any subgroups. In the 6 patients diagnosed BKVN, 5 of them were infected with subgroup I/b-1 (83.3%) and 1 patient was infected with subgroup IV/c-1 (16.7%). No significant difference between BKV genotypes was observed in relation to age, sex, HLA mismatch, viral load, BKVN, and immunosuppressive therapy.

Conclusions: This research indicated a high prevalence of BKV infection and BKV-I was predominant, followed by BKV-IV among recipients of renal transplant in Vietnam.