A field evaluation of the polymerase chain reaction procedure for the detection of bovine leukaemia virus proviral DNA in cattle

Simultaneous Use of Two Primer Pairs Increases the Efficiency of Polymerase Chain Reaction Assay in the Diagnosis of Bovine Leukemia Virus Infection

“…The PCR assay performed with serologically positive animals fails in about 1.4-9.6% of cases. 4,8 Recent investigations suggest that the negative results obtained by PCR may be attributable to extremely low amounts of provirus genetic material in the lymphocytes of infected animals. Several authors have reported the existence of so-called defective proviruses, whose genomes comprise large deletions, in the tissues of infected animals.…”

“…Occurrence of a relatively high percentage (up to 6.8%) of serologically negative and PCR-positive animals emphasizes the diagnostic importance of PCR. 4,8 The PCR assay will certainly not replace the serologic tests, which are less expensive and more convenient for large-scale screening, but PCR can be used as a supplementary diagnostic method for examination of highly valuable animals, e.g., breeding animals, that may be suspected as BLV carriers. Mycoplasma hyopneumoniae infection, swine enzootic pneumonia, causes considerable losses to the pig farming industry as a result of growth retardation and a prolonged fattening period.…”

Using PCR for early diagnosis of bovine leukemia virus infection in some native cattle

“…Several authors have shown that it is possible to establish BLV-free herds by identifying seropositive animals and eliminating them from the herds (HoffJorgensen, 1989;Klintevall et al, 1991;Lorin et al, 2007). Others demonstrated that serological control is not sensitive enough to find all BLV-infected cattle (Jacobs et al, 1992;Eaves et al, 1994;Ramanavicius et al, 2007). Problems also arise with animals exhibiting periodically or permanently low titers of BLV antibodies or low serum titers in the periparturient period (Coulston et al, 1990;Stone et al, 2000).…”

“…Problems also arise with animals exhibiting periodically or permanently low titers of BLV antibodies or low serum titers in the periparturient period (Coulston et al, 1990;Stone et al, 2000). Furthermore, serological tests cannot discriminate between passive maternal immunity and active immunity induced by bovine leukemia infection (Agresti et al, 1993;Eaves et al, 1994;Beier et al, 2004). Analyzing animals over a long period, Eaves et al (1994) showed that some naturally infected BLV provirus-carrying animals developed no BLV antibody titers detectable by ID or ELISA for several months or years after infection.…”

“…Furthermore, serological tests cannot discriminate between passive maternal immunity and active immunity induced by bovine leukemia infection (Agresti et al, 1993;Eaves et al, 1994;Beier et al, 2004). Analyzing animals over a long period, Eaves et al (1994) showed that some naturally infected BLV provirus-carrying animals developed no BLV antibody titers detectable by ID or ELISA for several months or years after infection. In infected cells, BLV is integrated into host DNA in the form of a provirus, which can be detected by different molecular biology methods.…”