Pathological Factors Affecting the Detection of BK Polyomavirus in Kidney Transplant Biopsies – UROP Spring Symposium 2021

Pathological Factors Affecting the Detection of BK Polyomavirus in Kidney Transplant Biopsies

Jahnavi Rajagopal


Pronouns: She/her/hers

Research Mentor(s): Evan Farkash, Assistant Professor
Research Mentor School/College/Department: Department of Pathology, Michigan Medicine
Presentation Date: Thursday, April 22, 2021
Session: Session 6 (4pm-4:50pm)
Breakout Room: Room 12
Presenter: 2

Event Link


Background: Effective immunosuppression places kidney transplant patients at risk of BK polyomavirus infection, which can cause graft damage or loss. Aggressive treatment is started if BK virus is detected in a transplant biopsy. However, a local infection may not be seen in a biopsy, particularly if it is in the initial stage and limited to the medulla. We seek to determine how BK titer and proportion of medulla affect the likelihood of detecting BK virus in a transplant biopsy in the initial stage of infection. Methods: A cohort of 733 renal transplant biopsies taken from 2006 to 2017 were collected from the Michigan Medicine Transplant Center. The biopsies correspond to the initial (n=182), resolution (n=95), post-clearance (n=152), persistent plateau (n=273), and isolated positive (n=25) phases of infection. I scored biopsies taken during the initial stage of BK infection according to Banff criteria, and recorded the percentage of cortex and medulla. Clinical data, such as BK titer at the biopsy date, was also recorded. I analyzed the data in Excel. Results: Biopsies with positive SV40 staining indicative of BK virus had a log10 peripheral BK titer of 4.28 +/- 0.41copies per µL, while biopsies without evidence of virus had a log10 BK titer of 3.02 +/- 0.98 copies per µL (p = 0.01 by t-test). Biopsies with virus were composed of 20.0% +/- 17.0% medulla, compared to 11.9% +/- 12.5% medulla in biopsies without virus (p = 0.39 by t-test). Conclusions: Our results indicate that viral titer is the main determinant of whether or not BK virus is seen on biopsy during the initial phase of infection. More biopsies would need to be scored to understand whether medulla sampling affects BK detection. This research could inform the decision to perform a biopsy based on the probability that the virus will be detected. If a biopsy is performed and is positive or negative for BK, comparing these results with the expected outcome may guide infection management.

Authors: Evan Farkash, Jahnavi Rajagopal, Madeline Vincent
Research Method: Clinical Research

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