detection of bovine leukemia virus infection by nested-pcr analysis

bovine leukemia virus (blv) is a retrovirus causing a chronic leukemia/lymphoma in cattle in many countries around the world. screening for antibodies by elisa has been the primary means of detecting the presence of this virus. it is not yet known if this assay will detect antibodies in all cattle during a concomitant bovine leukemia virus infection. the polymerase chain reaction (pcr) of the target proviral dna in peripheral blood mononuclear cells (pbml). in order to find a highly sensitive and efficient method for the diagnosis of blv infection in different matrices as well as blood samples, we have designed a nested-pcr method to detect blv-gag proviral dna in naturally infected cattle together with paraffin embedded blocks and degraded dnas. samples of natural infected cows (n=281), paraffin embedded (n=3) and degraded dna (n=10) were examined. when using elisa as a reference test, sensitivity and specificity for nested pcr were 0.85 and 0.84, respectively. interpretation of kappa scores for two methods was substantial (0.693). predictive value of a positive test was 0.82, and predictive value of a negative test was 0.86. the percentage of cows correctly classified by nested pcr assay was 85%.  this strategy have shown to allow detection at different experiments and had higher sensitivity in comparison with normal pcr. this latter technique is useful for mass screening and could be useful to detect proviral dna in paraffin embedded or old samples.