The notion of a clinical connection between disorders of the kidneys and the heart has been around since the days William Osler. In more recent years, it has been increasingly accepted that acute or chronic dysfunction of either organ often leads to acute or chronic dysfunction of the other. These AJKD articles highlight the cardiorenal connection, emphasizing what is known and reminding us that there is still much more to learn and understand.

Polyomavirus infection occurs in the transplanted allograft kidney and in the native kidney of immunosuppressed patients, and is usually related to BK virus (80%), JC virus (10%-20%), and less frequently simian virus 40 (SV40). Polyomaviruses are DNA and nonenveloped, with tropism for the urothelium. Transplanted kidneys have about 5% infection prevalence. Polyomavirus nephropathy usually presents as an asymptomatic acute or slowly rising creatinine. Polyomavirus infection can also present as nonhemorrhagic or hemorrhagic cystitis, and rarely as ureteral obstruction.