Evaluation of a PCR technique for the detection of Maedi-Visna proviral DNA in blood, milk and tissue samples of naturally infected sheep

A novel, simple polymerase chain reaction (PCR) protocol based on the amplification of a 291 base pair DNA fragment in the long terminal repeat (LTR) region of the Maedi-Visna (MV) provirus has been evaluated on samples collected from 115 sheep at the time of slaughter. The sheep came from Maedi-Visna virus (MVV) non-infected (<F>n=18</F>) or MVV infected (<F>n=97</F>) flocks, and the samples examined included peripheral blood leukocytes (PBLs; 115 sheep), milk cells (MCs; 64 sheep) and several tissue samples (TSs; 91 sheep). The LTR-PCR results were compared with the results of an indirect enzyme-linked immunosorbent assay (ELISA) and an agar-gel immunodiffusion test (AGIDT) performed on sera from the same animals obtained not only at the time of slaughter, but also in previous samplings. The LTR-PCR showed 100% specificity and an overall sensitivity of 98% in comparison with the two serological methods combined. Its sensitivity was lower when single types of samples were considered (84% in PBLs, 67% in MCs and 88% in TSs). It is concluded that this LTR-PCR can be used to complement serological tests and to perform studies of the pathogenesis of this lentiviral infection. [Copyright &y& Elsevier]