Biology subjects

Swann, O. C.

Publications and source records attributed to Swann, O. C..

5 recordsLinked to original sources

bioRxiv2025

Influenza A virus polymerase co-opts distinct sets of host proteins for RNA transcription or replication

The influenza A virus polymerase, consisting of a heterotrimer of three viral proteins, carries out both transcription and replication of the viral RNA genome. These distinct activities are regulated by viral proteins that vary in abundance during infection, and by various co-opted host cell proteins, which serve as targets for the development of novel antiviral interventions. However, little is known about which host proteins direct transcription and which replication. In this report, we performed a differential interactome screen to identify host proteins co-opted as either transcription-or replication-specific factors. We found that distinct sets of host proteins interact with the influenza polymerase as it carries out the different activities. We functionally characterised HMGB2 and RUVBL2 as replication-specific cofactors and RPAP2 as a transcription-specific cofactor. Our data demonstrate that comparative proteomics can be used as a targeted approach to uncover virus-host interactions that regulate specific stages of the viral lifecycle.

microbiology↗

bioRxiv2022

Avian Influenza A Virus polymerase can utilise human ANP32 proteins to support cRNA but not vRNA synthesis

Host restriction limits the emergence of novel pandemic strains from the Influenza A Virus avian reservoir. For efficient replication in mammalian cells, the avian influenza RNA-dependent RNA polymerase must adapt to use human orthologues of the host factor ANP32, which lack a 33 amino acid insertion relative to avian ANP32A. Here we find that influenza polymerase requires ANP32 proteins to support both steps of replication: cRNA and vRNA synthesis. Nevertheless, avian strains are only restricted in vRNA synthesis in human cells. Therefore, avian polymerase can use human ANP32 orthologues to support cRNA synthesis, without acquiring mammalian adaptations. This implies a fundamental difference in the mechanism by which ANP32 proteins support cRNA vs vRNA synthesis. ImportanceIn order to infect humans and cause a pandemic, avian influenza must first learn how to use human versions of the proteins the virus hijacks for replication - instead of the avian versions found in bird cells. One such protein is ANP32. Understanding the details of how host proteins such as ANP32 support viral activity may allow the design of new antiviral treatments that disrupt these interactions. In this work, we use cells that lack ANP32 to unambiguously demonstrate ANP32 is needed for both steps of influenza genome replication. Surprisingly however, we find that avian influenza can use human ANP32 proteins for the first step of replication without any adaptation, but only avian ANP32 for the second step of replication. This suggests ANP32 may have an additional role in supporting the second step of replication, and it is this activity that is specifically blocked when avian influenza infects human cells.

microbiology↗

bioRxiv2020

The furin cleavage site of SARS-CoV-2 spike protein is a key determinant for transmission due to enhanced replication in airway cells.

SARS-CoV-2 enters cells via its spike glycoprotein which must be cleaved sequentially at the S1/S2, then the S2 cleavage sites (CS) to mediate membrane fusion. SARS-CoV-2 has a unique polybasic insertion at the S1/S2 CS, which we demonstrate can be cleaved by furin. Using lentiviral pseudotypes and a cell-culture adapted SARS-CoV-2 virus with a S1/S2 deletion, we show that the polybasic insertion is selected for in lung cells and primary human airway epithelial cultures but selected against in Vero E6, a cell line used for passaging SARS-CoV-2. We find this selective advantage depends on expression of the cell surface protease, TMPRSS2, that allows virus entry independent of endosomes thus avoiding antiviral IFITM proteins. SARS-CoV-2 virus lacking the S1/S2 furin CS was shed to lower titres from infected ferrets and was not transmitted to cohoused sentinel animals. Thus, the polybasic CS is a key determinant for efficient SARS-CoV-2 transmission.

microbiology↗

bioRxiv2020

Mammalian ANP32A and ANP32B proteins drive alternative avian influenza virus polymerase adaptations

ANP32 proteins, which act as influenza polymerase co-factors, vary between birds and mammals. The well-known mammalian adaptation, PB2-E627K, enables influenza polymerase to use mammalian ANP32 proteins. However, some mammalian-adapted influenza viruses do not harbour this adaptation. Here, we show that alternative PB2 adaptations, Q591R and D701N also allow influenza polymerase to use mammalian ANP32 proteins. PB2-E627K strongly favours use of mammalian ANP32B proteins, whereas D701N shows no such bias. Accordingly, PB2-E627K adaptation emerges in species with strong pro-viral ANP32B proteins, such as humans and mice, while D701N is more commonly seen in isolates from swine, dogs and horses where ANP32A proteins are more strongly pro-viral. In an experimental evolution approach, passage of avian viruses in human cells drives acquisition of PB2-E627K, but not when ANP32B is ablated. The strong pro-viral support of ANP32B for PB2-E627K maps to the LCAR region of ANP32B.

microbiology↗

bioRxiv2020

Swine ANP32A supports avian influenza virus polymerase

Avian influenza viruses occasionally infect and adapt to mammals, including humans. Swine are often described as mixing vessels, being susceptible to both avian and human origin viruses, which allows the emergence of novel reassortants, such as the precursor to the 2009 H1N1 pandemic. ANP32 proteins are host factors that act as influenza virus polymerase cofactors. In this study we describe how swine ANP32A, uniquely among the mammalian ANP32 proteins tested, supports some, albeit limited, activity of avian origin influenza virus polymerases. We further show that after the swine-origin influenza virus emerged in humans and caused the 2009 pandemic it evolved polymerase gene mutations that enabled it to more efficiently use human ANP32 proteins. We map the super pro-viral activity of swine ANP32A to a pair of amino acids, 106 and 156, in the LRR and central domains and show these mutations enhance binding to influenza virus trimeric polymerase. These findings help elucidate the molecular basis for the mixing vessel trait of swine and further our understanding of the evolution and ecology of viruses in this host.

microbiology↗