Biology subjects

Whelan, M. V. X.

Publications and source records attributed to Whelan, M. V. X..

5 recordsLinked to original sources

bioRxiv2025

A modified cyclosporine enhances lentivector transduction ex vivo and in vivo by degrading IFITM3

Intrinsic innate immune barriers have evolved to suppress viral infection and can reduce effective gene delivery in gene therapy. We have developed BG147, a novel cyclosporine A analogue, optimised via structure-guided design to prevent inhibition of HIV cofactor Cyclophilin A and to specifically inhibit interferon-induced transmembrane proteins (IFITM1-3). BG147 enhances VSV-G pseudotyped lentiviral vector transduction ex vivo in hematopoietic stem and progenitor cells (HSPCs) and in in vivo ocular gene therapy of photoreceptor cells in mice. Upon BG147 treatment, IFITM proteins are mislocalised and degraded through lysosomal acidification-dependent pathways. IFITM3 levels functionally return in cells 96 h after BG147 washout. BG147 promises to transform ex vivo and in vivo eye gene therapies by transiently inhibiting intrinsic immune barriers mediated by IFITM proteins to enhance a wide range of protocols. One Sentence SummaryModified cyclosporine, BG147, enhances lentivector gene therapy transduction, ex vivo in HSPC and in vivo in mouse photoreceptors, by degrading IFITM3.

cell biology↗

bioRxiv2022

Global landscape of the host response to SARS-CoV-2 variants reveals viral evolutionary trajectories

A series of SARS-CoV-2 variants of concern (VOCs) have evolved in humans during the COVID-19 pandemic--Alpha, Beta, Gamma, Delta, and Omicron. Here, we used global proteomic and genomic analyses during infection to understand the molecular responses driving VOC evolution. We discovered VOC-specific differences in viral RNA and protein expression levels, including for N, Orf6, and Orf9b, and pinpointed several viral mutations responsible. An analysis of the host response to VOC infection and comprehensive interrogation of altered virus-host protein-protein interactions revealed conserved and divergent regulation of biological pathways. For example, regulation of host translation was highly conserved, consistent with suppression of VOC replication in mice using the translation inhibitor plitidepsin. Conversely, modulation of the host inflammatory response was most divergent, where we found Alpha and Beta, but not Omicron BA.1, antagonized interferon stimulated genes (ISGs), a phenotype that correlated with differing levels of Orf6. Additionally, Delta more strongly upregulated proinflammatory genes compared to other VOCs. Systematic comparison of Omicron subvariants revealed BA.5 to have evolved enhanced ISG and proinflammatory gene suppression that similarly correlated with Orf6 expression, effects not seen in BA.4 due to a mutation that disrupts the Orf6-nuclear pore interaction. Our findings describe how VOCs have evolved to fine-tune viral protein expression and protein-protein interactions to evade both innate and adaptive immune responses, offering a likely explanation for increased transmission in humans. One sentence summarySystematic proteomic and genomic analyses of SARS-CoV-2 variants of concern reveal how variant-specific mutations alter viral gene expression, virus-host protein complexes, and the host response to infection with applications to therapy and future pandemic preparedness.

systems biology↗

bioRxiv2022

SARS-CoV-2 Spike evolution influences GBP and IFITM sensitivity

SARS-CoV-2 spike requires proteolytic processing for viral entry. The presence of a polybasic furin-cleavage site (FCS) in spike, and evolution towards an optimised FCS by dominant variants of concern (VOCs), are linked to enhanced infectivity and transmission. Here we show that interferon-inducible antiviral restriction factors Guanylate binding proteins (GBP) 2 and 5 interfere with furin-mediated cleavage of SARS-CoV-2 spike and inhibit the infectivity of early-lineage Wuhan-Hu-1, while VOCs Alpha and Delta have evolved to escape restriction. Strikingly, we find Omicron is unique amongst VOCs, being restricted by GBP2/5, and also IFITM1, 2 and 3. Replacing the spike S2 domain in Omicron with Delta shows S2 is the determinant of entry route and IFITM sensitivity. We conclude that VOC evolution under different selective pressures has influenced sensitivity to spike-targeting restriction factors, with Omicron selecting spike changes that not only mediate antibody escape, and altered tropism, but also sensitivity to innate immunity.

microbiology↗

bioRxiv2021

Evolution of enhanced innate immune evasion by the SARS-CoV-2 B.1.1.7 UK variant

Emergence of SARS-CoV-2 variants, including the globally successful B.1.1.7 lineage, suggests viral adaptations to host selective pressures resulting in more efficient transmission. Although much effort has focused on Spike adaptation for viral entry and adaptive immune escape, B.1.1.7 mutations outside Spike likely contribute to enhance transmission. Here we used unbiased abundance proteomics, phosphoproteomics, mRNA sequencing and viral replication assays to show that B.1.1.7 isolates more effectively suppress host innate immune responses in airway epithelial cells. We found that B.1.1.7 isolates have dramatically increased subgenomic RNA and protein levels of Orf9b and Orf6, both known innate immune antagonists. Expression of Orf9b alone suppressed the innate immune response through interaction with TOM70, a mitochondrial protein required for RNA sensing adaptor MAVS activation, and Orf9b binding and activity was regulated via phosphorylation. We conclude that B.1.1.7 has evolved beyond the Spike coding region to more effectively antagonise host innate immune responses through upregulation of specific subgenomic RNA synthesis and increased protein expression of key innate immune antagonists. We propose that more effective innate immune antagonism increases the likelihood of successful B.1.1.7 transmission, and may increase in vivo replication and duration of infection.

microbiology↗

bioRxiv2020

SARS-CoV-2 sensing by RIG-I and MDA5 links epithelial infection to macrophage inflammation

SARS-CoV-2 infection causes broad-spectrum immunopathological disease, exacerbated by inflammatory co-morbidities. A better understanding of mechanisms underpinning virus-associated inflammation is required to develop effective therapeutics. Here we discover that SARS-CoV-2 replicates rapidly in lung epithelial cells despite triggering a robust innate immune response through activation of cytoplasmic RNA-ensors RIG-I and MDA5. The inflammatory mediators produced during epithelial cell infection can stimulate primary human macrophages to enhance cytokine production and drive cellular activation. Critically, this can be limited by abrogating RNA sensing, or by inhibiting downstream signalling pathways. SARS-CoV-2 further exacerbates the local inflammatory environment when macrophages or epithelial cells are primed with exogenous inflammatory stimuli. We propose that RNA sensing of SARS-CoV-2 in lung epithelium is a key driver of inflammation, the extent of which is influenced by the inflammatory state of the local environment, and that specific inhibition of innate immune pathways may beneficially mitigate inflammation-associated COVID-19. HighlightsO_LISARS-CoV-2 activates RNA sensors and consequent inflammatory responses in lung epithelial cells C_LIO_LIEpithelial RNA sensing responses drive pro-inflammatory macrophage activation C_LIO_LIExogenous inflammatory stimuli exacerbate responses to SARS-CoV-2 in both eplithelial cells and macrophages C_LIO_LIImmunomodulators inhibit RNA sensing responses and consequent macrophage inflammation C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=156 SRC="FIGDIR/small/424169v1_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@b07adborg.highwire.dtl.DTLVardef@51ddf7org.highwire.dtl.DTLVardef@c38f9aorg.highwire.dtl.DTLVardef@108db57_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗