PI3K–Akt pathway-independent PIK3AP1 identified as a replication inhibitor of the African swine fever virus based on iTRAQ proteomic analysis

Abstract

African swine fever (ASF) is a severe infectious disease that has a high global prevalence. The fatality rate of pigs infected with ASF virus (ASFV) is close to 100%; in the absence of a safe and reliable commercial vaccine, this poses a threat to the global pig industry and public health. To better understand the interaction of ASFV with its host, isobaric tags for relative and absolute quantitation combined with liquid chromatography-mass spectrometry was used to conduct quantitative proteomic analysis of bone marrow-derived macrophage cells infected with ASFV. Overall, 4579 proteins were identified; 286 of these were significantly upregulated and 69 were significantly downregulated after ASFV infection. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein-protein interaction network analyses were used to obtain insights into the dynamics and complexity of the ASFV-host interaction. In addition, immunoblotting revealed that the expression of PIK3AP1, RNF114, and FABP5 was upregulated and that of TRAM1 was downregulated after ASFV infection. Overexpression of PIK3AP1 and RNF114 significantly inhibited ASFV replication in vitro, but the suppressive effect of PIK3AP1 on ASFV replication was independent of the PI3K-Akt pathway. Further studies confirmed that ASFV MGF360-9L interacts with PIK3AP1 to reduce its protein expression level. Moreover, LY294002, an inhibitor of the PI3K-Akt pathway, inhibited ASFV replication, indicating the importance of the PI3K-Akt pathway in ASFV infection. This study identified the network of interactions between ASFV and host cells and provides a reference for the development of anti-ASFV strategies and for studying the potential mechanisms and pathogenesis of ASFV infection.