Lateral flow assays for the detection of African swine fever virus antigen are not fit for field diagnosis of wild boar carcasses : [Preprint]

African swine fever (ASF) is one of the most important viral diseases of domestic pigs and wild boar. Apart from endemic cycles in Africa, ASF is now continuously spreading in Europe and Asia. As ASF leads to severe but unspecic clinical signs and high lethality, early pathogen detection is of utmost importance. Recently, \point-of-care" (POC) tests have been intensively discussed for the use in remote areas but also in the context of on-farm epidemiological investigations and wild boar carcass screening. Along these lines, the INGEZIM ASFV CROM Ag lateral ow assay (Eurons Technologies Ingenasa) promises virus antigen detection under eld conditions within minutes. In the present study, we evaluated the performance of the assay with selected high-quality reference blood samples, and also with real eld samples from wild boar carcasses in dierent stages of decay from the ongoing ASF outbreak in Germany. While we observed a sensitivity of roughly 77% in freeze-thawed matrices of close to ideal quality, our approach to simulate eld conditions in direct carcass testing without any modication resulted in a drastically reduced sensitivity of only 12.5%. Freeze thawing increased the sensitivity to roughly 44% which mirrored the overall sensitivity of 49% in the total data set of carcass samples. A diagnostic specicity of 100% was observed. However, most of the German ASF cases in wild boar would have been missed using the lateral ow assay (LFA) alone. Therefore, the antigen-specic LFA should not be regarded as a substitute for any OIE listed diagnostic method and has very limited use for carcass testing at the point of care. For optimized LFA antigen tests, the sensitivity with eld samples must be signicantly increased. An improved sensitivity is seen with freeze-thawed samples, which may indicate problems in the accessibility of ASFV antigen.