Improvements in the detection of small ruminant lentivirus infection in the blood of sheep by PCR.

The polymerase chain reaction on blood samples has been considered a complement to serological methods for the detection of small ruminant lentiviruses (SRLV) infections in sheep and goats. This is a report on the results of a study to evaluate the use of the same blood sample for the detection of infected animals by ELISA and PCR. A comparison between the results obtained by applying PCRs targeting LTR and gag sequences on blood clot, serum and peripheral blood leucocytes was made. In addition to simplifying sampling and laboratory work, the use of blood clot samples with the gag-PCR improved remarkably the detection of infected animals. Finally, this study has shown the existence of a cell-free viremia in the serum of SRLV-infected sheep.