Evaluation of Cryopreserved Primary Swine Macrophages as a Substrate for African Swine Fever Virus Replication

African swine fever (ASF) is a highly contagious and often fatal viral disease of pigs that poses serious economic consequences to the swine industry due to its high mortality rate and rapid spread. Currently, the identification of infectious ASF virus (ASFV) is the confirmatory test when clinical samples are positive for ASFV by any other diagnostic methods. Detection of infectious ASFV requires the availability of primary swine macrophage cultures as a cell substrate. We demonstrate here that cryopreserved swine primary macrophages are a suitable cell substrate for the detection, isolation and propagation of ASFV, showing similar results as when fresh swine macrophages are utilized. The possibility of using cryopreserved macrophages for detecting infectious ASFV would improve the efficacy of diagnostics in ensuring the availability of macrophage cell cultures during an emergency response.