DEVELOPMENT OF REAL-TIME RT-PCR ASSAYS FOR SPECIFIC DETECTION OF FOOT-AND-MOUTH DISEASE VIRUS (FMDV) LINEAGES OF SEROTYPES O AND SAT2
Résumé
Introduction Foot-and-mouth disease (FMD) is a highly contagious viral disease caused by FMDV. Seven antigenically distinct FMDV serotypes and multiple lineages exist. Laboratory diagnosis relies on virological, molecular, and serological tests. During an outbreak, it is crucial to monitor circulating strains in real-time. The rtRT-PCR is a tool of choice for this purpose. Some assays already exist, targeting serotypes or higher levels of discrimination. In this study, we propose three new rtRT-PCR assays, targeting serotypes O and SAT2. Methods The rtRT-PCR assays designed in this study were either a response to an emergency (SAT2/V) or targeted lineages considered at high risk for Europe (O/EA-3 and O/ME-SA/SA-2018). VP1 sequences were retrieved from public databases to design primers and probes (validated in silico). Then, the assays were tested in vitro against a panel of FMDV strains from the EU-Reference Laboratory collection. Results The SAT2/V assay was tested with 65 strains and 100 % of SAT2/V samples were detected (36/36). The O/EA-3 assay was tested with 34 strains, and 94% of O/EA-3 samples were detected (17/18). Finally, the O/ME-SA/SA-2018 assay was challenged with 32 strains, and 92% of samples were detected (11/12). Discussion The three rtRT-PCR assays developed in this study present a good potential of detection (100%, 94% and 92% for SAT2/V, O/EA-3 and O/ME-SA/SA-2018 respectively). All three assays did not detect other strains tested (some exceptions for old isolates in two cases), selected according to specific rules (strains circulating in the same geographic area and/or involved in recent epizooties). Two of these assays have already been shared with laboratories due to outbreaks linked to the targets (SAT2/V in Algeria, and recently O/ME-SA/SA-2018 in Germany). Even if more samples should be tested to precisely define the accuracy of the assays, these PCR assays will be an additional tool to combat FMD.
