3.4 Specificity, cross-reactivity and diagnostic sensitivity of the multiplex assays
The specificity of the multiplex assays was evaluated against multiple isolates/species of the target as well as differential viruses. The CaP rule-out assays were evaluated against multiple CC isolates of LSDV, GPV and SPV, 36 CS (PaPVs), and multiple CC isolates of the non-target viruses BHV and PPRV. The FMD rule-out assays were evaluated against multiple CC isolates of the seven serotypes of FMDV (A, Asia1, C, O, SAT1, SAT2 and SAT3), 36 CS (PaPVs), and multiple CC isolates of the non-target viruses BVDV, VSV and BTV. The results show 100% specificity of the CaP rule-out (Table 4) and FMD rule-out (Table 5) assays with no cross-reactivity against any of the non-target differential viruses.
The DSe of the multiplex assays was assessed on CS from experimentally (CaPV and FMDV) and naturally (PaPV) infected animals. Thirty-five CaPV and 36 PaPV (BPSV and ORFV) specimens were tested by CaP rule-out assays and all tested positive (DSe 100%) (Table 4). Thirty-six PaPV (BPSV and ORFV) and 39 FMDV specimens were tested by FMD rule-out assays, out of which, 37 FMDV specimens (DSe 95%) and all 36 PaPV specimens (DSe 100%) tested positive by FMD rule-out assay (Table 5).