Fig. 1

Schematic representation of ORFV RPA-LFD assay principle for the detection of ORFV. a Amplifying FAM-biotin-linking ORFV nfo RPA amplicons, in the presence of target template (nt position 4465 bp–4736 bp on ORFV DNA polymerase gene), recombinase nfo endonuclease driven primers (RPA1F/Biotin labeled RPA1R) and FAM labeled probes produced FAM-biotin-linking ORFV nfo RPA. b Detecting the RPA amplicons by LFD assay. The amplicons are mixed with the appropriate buffer. Dipping the mixture on LFD strips (Milenia Biotec, Giessen, Germany), the RPA amplicons travel in a buffer stream to be trapped at the test line by biotin-ligands, resulting in an appearance of red-pink color indicative of a positive result. Non-captured gold particles move through the test line to be fixed at the control line by anti-rabbit antibodies, and then produce color serving as a flow control for the strip. In the absence of ORFV target amplicons, color will appear at a control line only