Polyoma BK virus pathology in renal allografts

Abstract

<h3>Aim</h3> With the advent of more potent and effective immunosuppression in the transplant setting, the role of polyoma BK virus (BKV) in renal graft outcome has gained increasing importance. Nevertheless, its prevalence and contribution to allograft damage and rejection remains unclear. We studied renal allograft biopsies received over a 5-year period for prevalence of BKV infection and possible relationship to graft pathology. <h3>Methods</h3> Archived formalin-fixed, paraffin-embedded renal allograft biopsies of 108 patients (age range 16–75 years;mean 39 years) were examined for immunohistochemically detectable BKV and graft pathology. BKV-positive biopsies were further elucidated by electron microscopy and immunoelectron microscopy. <h3>Results</h3> BKV was detected in renal tubular nuclei of 10 biopsies from eight patients (age range 17–53 years;mean 35 years), a prevalence (7.4%) at the high end of other reported studies. Tubulointerstitial rejection (Banff 1a and above) was detected in six (75%) BKV-positive patients compared to 46% of those without detectable BKV (<i>p</i>=0.030). One infected patient lost her graft. <h3>Discussion</h3> This study supports a deleterious effect of BKV on renal allografts. Because BKV is difficult to detect morphologically, a high index of suspicion and specific immunohistochemistry are required when examining renal allograft biopsies.