| Autor: |
Borge AJ; Norwegian Veterinary Institute, P.O. Box 64, 1431 Ås, Norway., Colitti B; Department of Veterinary Science, University of Turin, Largo P. Braccini 2, 10095 Grugliasco, TO, Italy., Rosati S; Department of Veterinary Science, University of Turin, Largo P. Braccini 2, 10095 Grugliasco, TO, Italy., Nordstoga AB; Norwegian Veterinary Institute, P.O. Box 64, 1431 Ås, Norway., Gjerset B; Norwegian Veterinary Institute, P.O. Box 64, 1431 Ås, Norway., Udjus K; Norwegian Veterinary Institute, P.O. Box 64, 1431 Ås, Norway., Nogarol C; In3diagnostic s.r.l., Largo P. Braccini 2, 10095 Grugliasco, TO, Italy., Chellappa S; Norwegian Veterinary Institute, P.O. Box 64, 1431 Ås, Norway., Samdal IA; Norwegian Veterinary Institute, P.O. Box 64, 1431 Ås, Norway., Lybeck K; Norwegian Veterinary Institute, P.O. Box 64, 1431 Ås, Norway. |
| Abstrakt: |
The Maedi-visna virus (MVV) causes a persistent infection in small ruminants, and its high genetic heterogeneity affects the performance of diagnostic tests when used in different populations. Therefore, the aim of this study was to develop a bead-based multiplex immunoassay tailored to detect antibodies against a Norwegian MVV strain. We used tissue samples from 14 PCR-positive sheep from a recent MVV outbreak in Norway to sequence the viral strain and produced recombinant antigens based on sequences from one animal. The assay included commercial TM-A and recombinant Norwegian p25, p16-25 and SU5 antigens. Cut-off values for each antigen were determined using receiver operating characteristic curves on 40 ELISA-negative and 67 ELISA-positive samples from the outbreak. The intraplate and interplate repeatability were investigated by testing a quadruplicate of five samples over three days, while the analytical sensitivity (aSe) and specificity (aSp) were measured in comparison to a commercial ELISA. The repeatability showed a coefficient of variation below 15% for most positive samples. The aSe was equal or higher for the multiplex assay than the ELISA, and the aSp of each antigen was 91.7, 93.3, 95.0 and 93.3% for p25, p16-25, SU5 and TM-A, respectively. The assay shows promising results; however, further evaluations of diagnostic characteristics are necessary before implementation in the Norwegian surveillance programme. |
