Viral infections of renal allografts--an immunohistochemical and ultrastructural study

Viral infections have been recognized as an integral part of both graft injury and rejection. On routine histology, viral infections are diagnosed only when fully established, by the presence of viral inclusions or cytopathic effect. Although renal transplants are routinely done in many centres in India, the incidence of viral infections is largely unkown. This study was aimed at detecting 5 viral infections namely, cytomegalovirus (CMV), BK polyoma Virus (BKV), Herpes Simplex Virus1 and 2 (HSV1 and 2) and Epstein Barr Virus (EBV) in renal biopsies from 321 renal allograft patients, using immunohistochemical and electron microscopic studies. Sixty two biopsies were selected from a total of 414 (belonging to 321 patients) for immunostaining on the basis of features suspicious of viral infections in hematoxylin and eosin stained sections. Immunostaining confirmed CMV infection in 8 biopsies, BKV infection in 31 biopsies and HSV1 in only 2 biopsies. HSV2 and EBV were not detected in any biopsy. Two biopsies showing CMV immunopositivity and 5 of BKV were further processed for electron microscopy, which supported the diagnoses. Thus, the study highlights the prevalence of BKV and CMV infections in renal transplant patients having graft dysfunction, to be 9.3% and 1.9%, respectively. Besides, only one case each was diagnosed as CMV infection and BKV infection in routine histopathological reporting, establishing the importance of immunohistochemical studies in early diagnosis of these viral infections.