Swine alveolar macrophage cell model allows optimal replication of influenza A viruses regardless of their origin

The importance of pigs in interspecies transmission of influenza A viruses has been repeatedly demonstrated over the last century. Eleven influenza A viruses from avian, human and swine hosts were evaluated for replication phenotypes at three physiologically relevant temperatures (41 degrees C, 37 degrees C, 33 degrees C) in an immortalized swine pulmonary alveolar macrophage cell line (IPAM 3D4/31) to determine whether this system would allow for their efficient replication. All isolates replicated well in IPAMs at 37 degrees C while clear distinctions were observed at 41 degrees C and 33 degrees C, correlating to species of origin of the PB2, reflected in distinct amino acid residue profiles rather than in one particular PB2 residue. A strong TNF-alpha response was induced by some mammalian but not avian IAVs, while other selected cytokines remained below detection levels. Porcine IPAMs represent a natural host cell model for influenza virus replication where the only condition requiring modification for optimal IAV replication, regardless of virus origin. Crown Copyright (C) 2016 Published by Elsevier Inc. All rights reserved.