ABSTRACT: Complete genome sequencing and comparative phylogenomics of multiple African swine fever virus (ASFV) field isolates of the virulent East African p72 genotype IX viruses
Project description:African swine fever virus (ASFV) is a large DNA virus that poses a major threat to the global swine industry. Its virion is encapsulated by an icosahedral capsid predominantly composed of the structural protein p72, which constitutes approximately one-third of the total virion mass. Despite its abundance, the mechanisms regulating p72 stability remain poorly understood. Here, we demonstrate that host-mediated stabilization of p72 is essential for efficient ASFV replication. Mass spectrometry of p72 co-precipitates identified host cyclophilin A (CypA, also known as PPIA) as a key binding partner of p72. CypA interacts with p72 both in vitro and in vivo, specifically engaging exposed regions of p72 via its hydrophobic cavity. CypA interaction stabilizes p72 by reducing K63-linked ubiquitination and preventing proteasomal degradation, whereas cyclic CypA inhibitors destabilize p72 by disrupting this interaction and promoting its ubiquitination. Importantly, genetic or pharmacological inhibition of CypA markedly impairs ASFV replication. Mechanistically, CypA inhibition disrupts viral factory formation and virion assembly by decreasing p72 protein accumulation without affecting its transcription. Together, our findings uncover a previously unrecognized host-dependent mechanism regulating capsid protein stability and highlight host CypA as a promising target for antiviral strategies against ASFV.
Project description:African swine fever virus (ASFV) produces a fatal acute hemorrhagic fever in domesticated pigs that potentially is a worldwide economic threat. Using an expressed sequence tag (EST) library-based antisense method of random gene inactivation and a phenotypic screen for limitation of ASFV replication in cultured human cells, we identified six host genes whose cellular functions are required by ASFV. These included three loci, BAT3 (HLA-B-associated transcript 3), C1qTNF (C1q and tumor necrosis factor-related protein 6), and TOM40 (translocase of outer mitochondrial membrane 40), for which antisense expression from a tetracycline-regulated promoter resulted in reversible inhibition of ASFV production by >99%. The effects of antisense transcription of the BAT3 EST and also of expression in the sense orientation of this EST, which encodes amino acid residues 450 to 518 of the mature BAT3 protein, were investigated more extensively. Sense expression of the BAT3 peptide, which appears to reversibly interfere with BAT3 function by a dominant negative mechanism, resulted in decreased synthesis of viral DNA and proteins early after ASFV infection, altered transcription of apoptosis-related genes as determined by cDNA microarray analysis, and increased cellular sensitivity to staurosporine-induced apoptosis. Antisense transcription of BAT3 reduced ASFV production without affecting abundance of the virus macromolecules we assayed. Our results, which demonstrate the utility of EST-based functional screens for the detection of host genes exploited by pathogenic viruses, reveal a novel collection of cellular genes previously not known to be required for ASFV infection. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Computed
Project description:African swine fever virus (ASFV) produces a fatal acute hemorrhagic fever in domesticated pigs that potentially is a worldwide economic threat. Using an expressed sequence tag (EST) library-based antisense method of random gene inactivation and a phenotypic screen for limitation of ASFV replication in cultured human cells, we identified six host genes whose cellular functions are required by ASFV. These included three loci, BAT3 (HLA-B-associated transcript 3), C1qTNF (C1q and tumor necrosis factor-related protein 6), and TOM40 (translocase of outer mitochondrial membrane 40), for which antisense expression from a tetracycline-regulated promoter resulted in reversible inhibition of ASFV production by >99%. The effects of antisense transcription of the BAT3 EST and also of expression in the sense orientation of this EST, which encodes amino acid residues 450 to 518 of the mature BAT3 protein, were investigated more extensively. Sense expression of the BAT3 peptide, which appears to reversibly interfere with BAT3 function by a dominant negative mechanism, resulted in decreased synthesis of viral DNA and proteins early after ASFV infection, altered transcription of apoptosis-related genes as determined by cDNA microarray analysis, and increased cellular sensitivity to staurosporine-induced apoptosis. Antisense transcription of BAT3 reduced ASFV production without affecting abundance of the virus macromolecules we assayed. Our results, which demonstrate the utility of EST-based functional screens for the detection of host genes exploited by pathogenic viruses, reveal a novel collection of cellular genes previously not known to be required for ASFV infection. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
Project description:African swine fever virus (ASFV) produces a fatal acute hemorrhagic fever in domesticated pigs that potentially is a worldwide economic threat. Using an expressed sequence tag (EST) library-based antisense method of random gene inactivation and a phenotypic screen for limitation of ASFV replication in cultured human cells, we identified six host genes whose cellular functions are required by ASFV. These included three loci, BAT3 (HLA-B-associated transcript 3), C1qTNF (C1q and tumor necrosis factor-related protein 6), and TOM40 (translocase of outer mitochondrial membrane 40), for which antisense expression from a tetracycline-regulated promoter resulted in reversible inhibition of ASFV production by >99%. The effects of antisense transcription of the BAT3 EST and also of expression in the sense orientation of this EST, which encodes amino acid residues 450 to 518 of the mature BAT3 protein, were investigated more extensively. Sense expression of the BAT3 peptide, which appears to reversibly interfere with BAT3 function by a dominant negative mechanism, resulted in decreased synthesis of viral DNA and proteins early after ASFV infection, altered transcription of apoptosis-related genes as determined by cDNA microarray analysis, and increased cellular sensitivity to staurosporine-induced apoptosis. Antisense transcription of BAT3 reduced ASFV production without affecting abundance of the virus macromolecules we assayed. Our results, which demonstrate the utility of EST-based functional screens for the detection of host genes exploited by pathogenic viruses, reveal a novel collection of cellular genes previously not known to be required for ASFV infection.
Project description:To systematically delineate the Protein–Protein Interaction (PPI) network between ASFV and host immune pathway proteins, and ASFV-ASFV PPI, we used the recombination-based library vs library high-throughput yeast two-hybrid (RLL-Y2H) screening system.
Project description:African swine fever virus (ASFV) has caused severe consequences for the global pig industry. In this study, we conducted a multi-organ proteomic analysis using a 4D label-free quantitative proteomics approach and mapped the organ-specific proteomic landscape during ASFV infection. This work overcomes the limitations of most existing studies, which are primarily restricted to in vitro cell models, and providesprovide a more comprehensive understanding of ASFV infection and pathogenesis. Notably, the viral D117L protein is identified as a critical modulator of host cellular responses, directly subverting the unfolded protein response (UPR) pathway through specific interactions with host UPR-associated proteins. Collectively, our work lays the foundation for understanding the pathogenesis of ASFV, providing potential therapeutic strategies against African swine fever (ASF).
Project description:In field studies and carefully controlled artificial infections, there is host variation in response to ASF infections. To better understand the mechanisms underlying this diversity and distinguish between resilient and susceptible pigs to African Swine Fever (ASF), the differentially expressed genes (DEGs) were studied between the recovered versus non-recovered pigs before and after an infection challenge and also among non-recovered animals over time. In total, 17 Babraham pigs were sampled. Twelve animals were randomly immunized with low virulent ASFV isolate, and the others received the sham vaccine. All animals were then challenged with the virulent ASFV isolate 18 days after the immunization. Except for five animals, all showed clinical signs and dead between 4 and 6 days later. RNA sequencing was done for whole blood samples collected pre-infection, one day, and one week post-infection.
Project description:African swine fever virus (ASFV) causes a fatal disease with up to 100% mortality in domestic pigs and wild boar (species Sus scrofa), leading to significant economic losses for swine production. Unlike other eukaryotic viruses, ASFV encodes a histone-like nucleic acid-binding protein, pA104R. The A104R gene is highly conserved and present in all ASFV isolates of different genotypes. Moreover, A104R-like sequences have been identified in the genomes of soft ticks, which can replicate and transmit ASFV. Using a virulent genotype IX field isolate from Kenya, we analyzed the importance of A104R for viral replication in a permissive wild boar cell line (WSL). In this study, we confirmed that A104R is not essential for in vitro replication of ASFV. Loss of A104R did not detectably affect viral DNA replication or RNA transcription, but led to a moderate reduction of virus titers and plaque sizes. Substitution of A104R by a similar ASFV-like element derived from the genome of an Ornithodoros moubata soft tick was not capable of rescuing the deletion mutant phenotype. In contrast, reintroduction of the authentic A104R open reading frame (ORF) into the deletion mutant fully restored wild-type virus growth properties. In accompanying studies, we verified the DNA binding activities of the ASFV-, and of the tick-derived A104R protein (pA104R), and performed mass spectrometric analyses of the pA104R interactome. These experiments revealed besides DNA-dependent co-precipitated proteins, also specific, DNA-independent protein-protein interactions of pA104R with other viral and cellular proteins.
Project description:African swine fever virus (ASFV) causes a highly fatal disease in domestic pigs, resulting in substantial economic losses to the global swine industry. Vaccine development continues to be hindered by limited characterization of viral proteins and their functional redundancies. In this study, we employ combined experimental and computational approaches to characterize the ASFV pI73R protein, which contains a Z-DNA binding domain and plays a critical role in ASFV virulence and pathogenesis. We demonstrate that pI73R shares significant structural similarity with transcription factors of the forkhead box (FOX) protein family. Overexpression of pI73R results in downregulation of CRNKL1, a core spliceosome component, suggesting a potential mechanism by which pI73R modulates host protein synthesis. Using high-resolution mass spectrometry, we map the pI73R interactome and identify the host protein GNB1 as a novel direct interactor of pI73R which may facilitate its nuclear transport. Furthermore, we show that pI73R exhibits consistent oligomerization and expression across different ASFV genotypes, highlighting its functional importance. Taken together, these results provide new insights into pI73R function, ASFV-host dynamics, and offer promising directions for antiviral strategy development.