Young Patients with Alport Syndrome at Higher Risk for Kidney Infections with BK Virus after Transplant, Study Finds

Children and adolescents with Alport syndrome who underwent kidney transplants are at higher risk for developing kidney infections by BK virus, a South Korean study suggests.

The study, “Higher Incidence of BK Virus Nephropathy in Pediatric Kidney Allograft Recipients with Alport Syndrome,” was published in the Journal of Clinical Medicine.

BK virus is a common polyomavirus that is present in at least 90% of children in the first decade of life. This virus lives in the urinary and genital tracts but in people with healthy immune systems, the virus remains without causing damage.

In immunocompromised patients, or patients taking immune suppressants — such as those undergoing kidney transplants — the virus takes advantage and leads to an infection called BK virus nephropathy (BKVN) that could lead to transplant dysfunction or loss.

Scientists have observed that patient features such as age, sex, and immunosuppression status constitute risk factors for BKVN in adult patients undergoing kidney transplants. However, this information is lacking for younger patients.

In this study, researchers did a retrospective analysis of 195 patients, younger than 20, who underwent kidney transplants at Seoul National University Hospital between 2001 and 2015. From the 195 patients, 168 of them were tested for BK virus by molecular analysis.

Thirty (17.9%) out of the 168 patients had a positive test for BK virus in their blood about 12.6 months after transplantation.

More than one year (13.4 months) after their transplants, six patients (3.6%) were diagnosed with BKVN.

The researchers saw that 50% of the patients with BKVN had Alport syndrome, whereas 4.3% of patients without infection had this disease — in total, 10 patients were diagnosed with Alport syndrome. The analysis identified Alport syndrome as a significant risk factor for BKVN.

Overall, BK virus was present in 30% of patients with Alport syndrome, but every Alport patient who tested positive for the virus progressed to BKVN. BK virus was detected in 17.1% of the other non-Alport patients, with 11.1% of these progressing to BKVN.

The team believes that the explanation for BKVN prevalence in Alport syndrome patients is linked to physiologic defects in the architecture of these patients’ kidneys which makes it easier for the virus to infect and propagate.

The BKVN group of patients was followed between 2.2 to 8.3 years after transplant, and the team observed that no patient experienced transplant loss. Nonetheless, there was a clear impairment of kidney function in these patients. Three out of six patients that developed BKVN had successfully cleared the virus.

The researchers highlight that Alport syndrome should be considered a significant risk factor for BKVN, and a longer and more detailed virus screening in these patients is recommended.

“Considering that Alport syndrome was a significant risk factor for BKVN in this study, a more meticulous screening for Alport syndrome patients is recommended, and for a longer period after kidney transplantation,” the researchers wrote, adding that “when BK viremia is detected from screening, it is recommended that immunosuppression be reduced.”