Serologische und virologische Untersuchungen über das Vorkommen der BLV-Infektion in einer Milchviehherde in Syrien

237 cattle of a dairy herd in Syria were tested for anti-BLV antibody by the ELISA. 194 animals were additionally examined by the agar gel immunodiffusionstest (AGID) on BLV antibodies and 100 by polymerase chain reaction (PCR) for BLV provirus. BLV specific antibodies were determined by means of ACID and ELISA at 62.9% and 69.2% of the examined animals, respectively. Using the PCR method the BLV provirus was detected in 89% of the investigated cattle. Only one ELISA seropositive animal was negative for BLV provirus. The results show the high BLV contamination of this herd and lead to the presumption of wide spread enzootic bovine leukosis in Syria. In the case of the diagnosis of BLV-infection, the PCR-technique compared to the serological tests proved to be: much more sensitive. By the detection of BLV antibody, the ELISA showed a higher sensitivity than the AGID and in this way, is advisable as a method of choice for screening investigations. Restriction enzyme and sequence analysis of PCR-amplificates demonstrate that different BLV provirus variants (A, B and C) in the examined herd occur, where the variant C which a high similarity to an Australian BLV provirus isolates showed, occurred mast frequently at 92.5%