Renal tubular viral cytopathic changes Renal tubular polyoma virus inclusions The inclusions are generally accompanied by a patchy pleomorphic interstitial infiltrate with lymphocytes, plasma cells, and occasional neutrophils with associated interstitial edema, tubulitis, and tubular injury. Infected tubular epithelial cells have enlarged nuclei with amorphous inclusions. 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). Renal tubular nuclear inclusions have a ground-glass appearance with irregular central clearing, or a coarse, vesicular appearance. Distal tubules are involved more often than proximal tubules. There may be only medullary involvement in early stages, and parietal epithelial cells may be involved in later stages of the infection. Infected epithelial cell nuclei stain with antibody to the large T antigen of the SV40 virus, which serves as a surrogate marker of human polyomavirus infection.