Protective effects of a live attenuated bovine leukaemia virus vaccine with deletion in the R3 and G4 genes

In this study the protective effects of a live attenuated bovine leukaemia provirus (pBLVDX) with deletion in the R3 and G4 genes were tested. Six out of six sheep appeared to resist challenge with parental BLV344. Two out of three animals transfected with pBLVDX were protected against challenge wit h bovine leukaemia virus (BLV) from a naturally infected cow. As a model fo r the protection against infection by members of the human T-lymphotropic v irus/BLV group, these data provide evidence that a DNA-based vaccination wi th an attenuated provirus is able to protect against challenge infections.