Polyomavirus BK

Abstract

Polyomavirus hominis 1, better known as BK virus (BKV), infects up to 90% of the general population. However, significant clinical manifestations are rare and limited to individuals with impaired immune functions. BKV has been associated with diverse entities such as haemorrhagic cystitis, ureteric stenosis, vasculopathy, pneumonitis, encephalitis, retinitis, and even multi-organ failure. In addition, BKV has been implicated in autoimmune disease and possibly cancer. Due to high prevalence and frequent reactivation, the role of BKV in some of these pathologies has been difficult to define. Development of BKV diseases is likely to require complementing determinants in the host, the target organ, and possibly the virus, that are subject to modulators such as immunosuppression. These complex aspects are highlighted in polyomavirus-associated nephropathy (PAN), an emerging disease in renal allograft recipients that may jeopardise the progress in renal transplantation accomplished in the past 10 years. Intervention is difficult due to the lack of specific antivirals and relies mostly on improving immune control. Diagnostic strategies using urine cytology and BKV load measurements in plasma have led to earlier diagnosis of PAN, which increased the success rate of intervention. Case series suggest that cidofovir might be effective, especially when combined with reduced immunosuppression.

Histological Patterns of Polyomavirus Nephropathy: Correlation with Graft Outcome and Viral Load

“…In contrast, a status of high-level viral replication with associated tissue destruction occurs only in a minority of patients and it has been best characterized in renal allografts (PVAN). Pathological studies documenting the exact progression of polyomavirus reactivation in the kidney are lacking, although it has been speculated that viral reactivation starts in the urothelium (bladder, ureters) and renal medulla with later involvement of the rest of the kidney (18,19,27,28).…”

“…secondary to tubular injury). Excessive tissue destruction may occur once the immune system recovers its capabilities (immune reconstitution response) (28,(33)(34)(35). Irrespective of the underlying etiopathogenesis, florid inflammatory responses in PVAN are often associated with parenchymal fibrosis (scarring) (9,29).…”

High burden of BK virus-associated hemorrhagic cystitis in patients undergoing allogeneic hematopoietic stem cell transplantation

“…Several studies have provided a better understanding of post-engraftment BKV-HC pathogenesis, suggesting a dual chronological process. 9 The concept of immune reconstitution syndrome with BKV acting as a trigger for immune response 20 represents a new perspective to be considered when testing preventive and/or therapeutic approaches. Standard treatment for BKV-HC has not been established yet.…”

Identification of the novel KI Polyomavirus in paranasal and lung tissues

“…JCV can cause a demyelinating disease known as progressive multiphocal leukoencephalopathy (PML) which occurs mainly in AIDS patients [Gordon and Khalili, 1998]. BKV can be responsible of a tubular nephritis, which can lead to allograft failure in renal transplant recipients and hemorrhagic cystitis in hematopoietic stem cell transplant recipients [Nickeleit et al, 2002;Hirsch and Steiger, 2003;Chen et al, 2004].…”