BOVINE PAPILLOMAVIRUS TRANSMISSION AND CHROMOSOMAL-ABERRATIONS - AN EXPERIMENTAL-MODEL

Enzootic haematuria and urinary bladder cancer in cattle are associate d with feeding on bracken fern and bovine papillomavirus (BPV) infecti on. An increased rate of chromosomal aberrations in peripheral blood l ymphocytes from chronically affected haematuric cows raised in bracken fern pastures has been reported, suggesting the presence of BPV in th e peripheral blood of afflicted animals. The purpose of the present in vestigation was to examine the role of peripheral blood as a potential BPV-transmitting agent and search for clastogenic effects in experime ntally infected animals kept on a bracken fern-free diet. Healthy cows were inoculated with blood samples of haematuric animals every two we eks for 18 months. Recipient cows, their offspring, donor animals and a control group were kept on a bracken fern-free diet throughout the e xperiment. Clinical and molecular analyses for detection of BPV infect ion were carried out periodically in all groups, Short-term lymphocyte cultures were performed to assess chromosomal aberration levels. The donor cows, the recipient cows and their offspring presented increased levels of chromosomal aberrations. BPV-2 DNA was identified by Southe rn blotting, PCR and cycle-sequencing of PCR products in peripheral bl ood of donor and recipient animals and in the progeny of recipient ani mals. Data support both the concept that BPV can be transmitted throug h blood and the hypothesis that infection with the virus causes the cl astogenic alterations observed in the present experimental model. The presence of BPV-2 DNA and chromosomal alterations in peripheral blood of offspring at the moment of birth is evidence for vertical transmiss ion of BPV.