Pathomorphological studies and detection of bovine papilloma viruses in wart-like lesions/growths in reticulum of buffaloes

The present investigation was carried out to study the pathomorphology of wart-like lesions/growths in reticulum of buffaloes and their association with different bovine papilloma virus (BPV) types. A total of 19 tissue samples of reticulum were included in this study. Grossly, single to multiple, pin-head to pea-nut sized, sessile, pedunculated, dome shaped and mushroom-like growths with thickened reticular pillars were observed. Histopathologically, these were diagnosed as fibropapilloma, papilloma, hyperplasia and reticulitis. Ultrastructurally, the pleomorphic spinocytes containing variable shaped nuclei with scanty heterochromatin and distinct nuclear membrane were observed. PCR revealed presence of BPV-1, -2 and -5 DNA alone or their mixed infections. Quantitative real-time PCR revealed varying amount of viral DNA copy numbers of BPV-1, -2 and -5. Immunostaining for Ki-67 in fibropapilloma cases varied with random distribution of the immunopositive cells. As compared to basal cells; more number of Ki-67 immunopositive cells was observed in suprabasal cells. Cyclooxygenase-2 (COX-2) expression showed cytoplasmic staining with occasional membrane staining, especially in koilocytes. The stromal inflammatory cells in reticulitis associated cases were also moderately positive for COX-2 immunostaining. In conclusion, BPV-1, -2 and -5 were associated either alone or their mixed infections with reticular wart-like lesions/growths in buffaloes. The basal and suprabasal cells of the reticular fibropapilloma were cellular proliferation sites. In conclusion, the present investigation revealed that the growths/wart-like lesions occurring in the reticulum of slaughtered buffaloes are associated with infection of BPV-1, -2 and -5, as DNA of these viruses were detected in such cases.