DNA fingerprints of sheep using an M13 probe.

The bacteriophage M13 DNA was used to detect hypervariable minisatellites in several families of Booroola sheep as well as Merino and Suffolk sheep. Digestion of sheep DNA gave rise to three to eight fragments with different restriction enzymes demonstrating considerable polymorphism between the different breeds. The length of informative DNA fragments varied in size from 6 to 20kb. The DNA fingerprints generated were individual specific and allowed for differentiation between closely related animals. The pattern obtained with sheep DNA was different from that observed with humans and other vertebrates in the proportion of high molecular weight DNA fragments present. Pedigree analysis of DNA patterns of dams and their offspring for several sets of twins and triplets showed a clear distinction between individuals and failed to reveal the presence of monozygosity

Recombinant viral vaccines for enzootic bovine leucosis

Recently published studies on the development and use of recombinant vaccinia virus (VV) vaccines incorporating either the complete envelope (env) gene or only a fragment of the env gene consisting of the coding sequence for the env glycoprotein 51 (gp51) and part of gp30 of the bovine leukaemia virus (BLV) are described. It has been reported that vaccination of sheep with recombinant VV vaccines containing the complete env gene appears to protect sheep against challenge infection with BLV. The evidence for this protection is based on the lack of persistence of high titres of anti-gp51 antibodies compared with unvaccinated BLV infected controls, on the enhanced CD4 proliferative responses to specific BLV gp51 synthetic peptides in the vaccinated sheep, and on the inability to detect BLV pro-virus by polymerase chain reaction in the vaccinated sheep after 4 months following challenge infection compared with continual detection in unvaccinated sheep over a 16 month trial period. It has been suggested that cell-mediated immune responses may be an important aspect of protective immunity against BLV infection and it has been reported that large tracts of amino acid sequences within the env and pol genes are highly conserved in different isolates from different countries which is of importance in designing peptide derived vaccines