Occurrence of enzootic bovine leukaemia virus in the visceral organs of naturally infected animals

The purpose of the experiment was to explain if bovine leukaemia provirus, which is undetectable in blood, can occur in different tissues and organs o f naturally infected, serologically positive animals. The following tissue samples were the source for DNA analysis: lymph nodes, spleen, kidney the r ight cardiac auricle, muscles, liver, abomasum wall, small intestine, bone marrow, medulla spinalis, brain, peritoneum, orbit and udder, A total of 10 5 DNA samples from different visceral organs were examined using PCR techni que. The presence of provirus DNA was confirmed in tissue samples from two cows. Provirus was present in tissues obtained from the right cardiac auric le, brain and spleen. There was no BLV provirus in the organs of the remain ing 10 cows. The obtained results indicate that the presence of BLV in some tissues cannot be excluded. The main reason for the difficulty in detectin g BLV provirus in serologically positive animals is its imperceptible amoun t contained in peripheral blood lymphocytes which, in turn, is caused by do wn regulation of transcription of BLV nucleic acids.