EN
The total usefulness of the nested PCR method in the detection of infections of cattle with BLV has been confirmed. The efficiency of DNA amplification of BLV with the PCR method was studied in 162 cows from 2 farms. These investigations were conducted by the classic (standard) PCR method with ZM2/ZM3 exterior primers and by the nested PCR method with ZM4/ZM5 interior primers. The DNA product amplification of the first primers was 340 pb, while second primers - 218 pb. The control of genetic material of BLV showed 58 (58.5%) positive results by the standard PCR and 87 (87.8%) positive results by the nested PCR, in 99 cows of the L farm with 54 of ELISA positive results. A number of positive results with standard PCR was 33 (52.3%) and 60 (95.2%) with nested PCR method in the P farm, where the sorological control showed 100% ELISA positive results. It should be stressed that among 45 of ELISA negative results, 9 (20%) positive results with standard PCR and 32 (71.1%) with nested PCR method were demonstrated. These results have underlined the high usefulness of nested PCR method and of using the whole blood of infected cows in the control of BLV infection.