Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2003
Publication Date: 2/1/2004
Citation: Afonso, C., Piccone, M.E., Zaffuto, K.M., Neilan, J.G., Kutish, G., Lu, Z., Balinsky, C.A., Gibb, T., Bean, T.R., Zsak, L., Rock, D.L. 2004. African swine fever virus multigene family 360 and 530 genes affect host interferon response.. Journal of Virology. (2004) 78 (4):1858-1864. Interpretive Summary: Microarray technology is a reliable and powerful tool for gene expression profiling and for identification of the potential function of genes. In this paper we have used a cDNA 'chip hybridization to investigate the role of multigene family 360 and 530 genes (MG F360) of African swine fever virus (ASFV). By comparing the gene expression patterns of wild-type virus and MDF360/540 deletion mutant in infected cells, we proposed that MG360/540 genes either directly or indirectly suppress a type I IFN response. This is the first report using swine macrophages microarrays manufactured in PIADC, USDA.
Technical Abstract: African swine fever virus (ASFV) multigene family 360 and 530 (MGF360/530) genes affect viral growth in macrophage cell culture and virulence in pigs (L. Zsak, Z. Lu, T.G. Burrage, J.G. Neilan, G.F. Kutish, D.M. Moore, and D.L. Rock, J. Virol. 75:3066-3076, 2001). The mechanism by which these novel genes affect virus-host interactions is unknown. To define MGF360/530 gene function, we compared macrophage transcriptional responses following infection with parental ASFV (Pr4) and an MGF360/530 deletion mutant (Pr4delta35). A swine cDNA microarray containing 7,712 macrophage cDNA clones was used to compare the transcriptional profiles of swine macrophages infected with Pr4 and Pr4delta 35 at 3 and 6 h post infection (hpi). While 3 hpi most (7,564) of the genes had similar expression levels in cells infected with either virus, 38 genes had significantly increased (>2.0-fold, P< 0.05) mRNA levels in Pr4delta35-infected marophages. Similar up-regulation of these genes was observed at 6 hpi. Viral infection was required for this induced transcriptional response. Most Pr4delta35 up-regulated genes were part of a type I interferon (IFN) response or were genes that are normally induced by double-stranded RNA and/or viral infection. These included monocyte chemoattractant protein, transmembrane protein 3, tetraticopeptide repeat protein 1, a ubiquitin-like 17-kDa protein, ubiquitin-specific protease ISG43, an RNA helicase DEAD box protein, GT-binding MX protein, the cytokine IP-10, and the PKR activator PACT. Differential expression IFN early-response genes in Pr4delta 35 relative to Pr4 was confirmed by Northern blot analysis and real-time PCR. Analysis of IFN-alpha mRNA and secreted IFN-alpha in mock- and Pr4-infected macrophages but significant IFN-alpha levels at 24 hpi in Pr4delta 35-infected macrophages. The absence of IFN-alpha in Pr4-infected macrophages suggests that MGF360-530 genes either directly or indirectly suppress a type I IFN response. An inability to suppress host type I IFN responses may account for the growth defect of Pr4delta35 in macrophages and its attenuation in swine.