Biology subjects

Daly, J. M.

Publications and source records attributed to Daly, J. M..

9 recordsLinked to original sources

bioRxiv2026

Comparative analysis identifies a shared topological organisation among divergent intergenic RNAs

Biological function is often inferred from sequence conservation or structural similarity. However, many viral RNAs maintain regulatory functions despite extensive diversification of both sequence and structures. Using arenavirus intergenic regions (IGRs) as a model system, we investigated what level of RNA organization remains conserved when these conventional sequence-structure-function relationships break down. Combining cryogenic OrbiSIMS guided RNA structure determination with graph theory-based analysis of fifty-eight IGRs across phylogenetically diverse arenaviruses, we discovered that IGR topology, defined by the connectivity and relative integration of individual stem-loop elements, is consistently arranged around a highly connected helical core that persists across divergent IGR folds. Quantitative centrality analyses further revealed that topologically peripheral stem-loops are comparatively sparse and variable across the phylogenetic classes. Investigation of the functional consequence of the peripheral elements in Golden Gate virus (a reptile arenavirus) S-IGR revealed selective association with interferon-induced and antiviral RNA-binding proteins in human host cells infected with recombinant Lymphocytic Choriomeningitis virus (a distantly related human arenavirus). Taken together, these findings identify graph-defined topology as a recurrent organisational feature among divergent arenavirus IGRs that is not captured by sequence identity or global RNA-structure similarity. The data are consistent with a model in which a topologically central helical organisation may be associated with conserved regulatory capacity, whereas structurally variable peripheral elements may contribute to lineage- or segment-specific host-factor interaction profiles.

biophysics↗

bioRxiv2026

Pseudotyped virus-based platform and structural analysis reveal potential cross-reactivity sites between influenza C and D viruses

Influenza C (ICV) and influenza D (IDV) viruses belong to the Orthomyxoviridae family and are classified in the genera Gammainfluenzavirus and Deltainfluenzavirus, respectively. Although the main reservoir of ICV is humans, IDV is mainly found in cattle. To date, the zoonotic potential of IDV has not been fully elucidated. ICV and IDV share about 50% homology at the genetic level, and both express hemagglutinin esterase fusion (HEF) glycoproteins on the surface for the dual purpose of binding the receptor and releasing new virions. Using pseudotyped viruses (PVs) in a pseudotyped virus-based microneutralisation assay (pMN), some bovine serum samples showed strong neutralisation of both ICV and IDV. In silico analyses were performed to explore the molecular basis of this phenomenon. HEF structures were recovered from the Protein Data Bank, epitopes were predicted using BepiPred, and sialic acid receptor docking was evaluated with HDOCK. Five potential epitopes were selected, and mutual substitutions of amino acid residues were introduced to generate mutant ICV and IDV HEFs and corresponding PVs. Although only mutant IDV PVs were successfully produced, a reference ICV antiserum showed high neutralising activity against one construct, indicating the exposure of an ICV-like antigenic site within the IDV framework. Herein we provide evidence consistent with the existence of antigenic sites shared between ICV and IDV, which could be exploited for cross-protective vaccine design, through integrated computational and experimental investigations.

immunology↗

bioRxiv2026

Direct Virus-Bacteria Binding Enhances Streptococcus equi subsp. zooepidemicus Colonisation and Bacterial-Driven Immune Activation During H3N8 Equine Influenza A Virus Co-Infection

Respiratory viral-bacterial co-infections cause severe disease across species, yet the molecular mechanisms underlying enhanced pathogenesis remain poorly understood. This study characterised H3N8 equine influenza A virus (IAV) and Streptococcus equi subspecies zooepidemicus (SEZ) co-infections using complementary ultrastructural and transcriptomic approaches. Transmission electron microscopy demonstrated direct physical binding between spherical (A/equine/Miami/63) and filamentous (A/equine/Sussex/89 and A/equine/Newmarket/5/2003) IAV isolates and SEZ, including when SEZ was heat-inactivated ({theta}SEZ). Lectin staining revealed that SEZ expresses predominantly 2,3-linked sialic acids, the receptor for equine IAV. However, virus-bacteria binding persisted despite neuraminidase treatment. Scanning electron microscopy quantification demonstrated that viral pre-infection significantly enhanced bacterial adherence to cells of the DH82 canine macrophage-like cell line (2-fold increase, p<0.01) but not ExtEqFL (equine lung-derived) cells, revealing cell-type-specific enhancement. RNA-sequencing analysis showed that bacterial infection drove most transcriptional changes during co-infection with little difference in the number of differentially expressed genes (DEGs) between infection with SEZ alone (146 DEGS) or after pre-infection with either A/equine/Sussex/89 (166 DEGS) or A/equine/Newmarket/5/2003 (149 DEGS). Validation of upregulation of selected cytokines by RT-qPCR and ELISA demonstrated that SEZ infection drives dramatic cytokine upregulation compared to mock or {theta}SEZ controls. Viral pre-infection did not alter the SEZ-induced pro-inflammatory cytokine responses (IL-6, IL-8, TNF-) but significantly reduced IFN-{beta} expression compared to SEZ infection alone. These findings suggest that direct virus-bacteria physical interactions may drive cell-type-specific enhancement of bacterial colonisation, fundamentally advancing our understanding of respiratory co-infection pathogenesis.

microbiology↗

bioRxiv2026

Serine proteases are required to activate influenza D virus haemagglutinin-esterase fusion (HEF) protein

Influenza D virus (IDV), the most recently identified member of the Orthomyxoviridae, was first isolated from pigs but cattle have been identified as the reservoir host. To date, IDV has not been confirmed to cause human disease. Like the haemagglutinin (HA) of influenza A virus (IAV) and the haemagglutinin-esterase fusion (HEF) protein of influenza C virus (ICV), the IDV HEF is produced as a precursor protein (HEF0) that must be proteolytically cleaved by host cell proteases (into HEF1 and HEF2) to gain its fusion capacity. The proteases that activate IAV HA have been extensively studied, but those responsible for activation of IDV HEF were unknown. Identifying these proteases is key to understanding early virus-host interactions and host restriction. Therefore, we generated ICV and IDV pseudotyped viruses (PVs) in HEK 293T producer cells with or without co-transfection of plasmids expressing different type II serine proteases. Subsequent transduction of swine testicular (ST) cells indicated strong activation of both ICV and IDV PVs by the human airway trypsin-like protease (HAT) and its swine homologue (swAT). Furthermore, like influenza A/Puerto Rico/8/34 (H1N1) virus, addition of exogenous protease is not essential for IDV replication in MDCK II cells, most likely due to endogenous expression of matriptase. In conclusion, our data unveil new information on host cell proteases that activate ICV and IDV HEF proteins. Importantly, the data suggest that protease specificity is not a factor in restriction of IDV replication in the human upper respiratory tract.

microbiology↗

bioRxiv2026

Isothermal Detection of Influenza D using RT-LAMP

The Orthomyxoviridae family includes influenza D virus (IDV), an emerging pathogen primarily affecting cattle and swine, with evidence of cross-species transmission and potential zoonotic risk. Although active human infections have yet to been confirmed, high seroprevalence in cattle-exposed populations highlights the need for continued surveillance. Here, a rapid, field-deployable RT-LAMP assay for IDV detection was developed and validated, with 99.2% specificity and sensitivity ranging from 95.6% (Cq < 30) to 81.8% (Cq < 40). This method offers a cost-effective, accessible alternative to RT-qPCR, enabling improved monitoring of IDV, and reinforcing preparedness for emerging influenza threats.

microbiology↗

bioRxiv2025

Development and optimisation of Influenza C and Influenza D pseudotyped viruses

To facilitate the study of influenza C (ICV) and influenza D (IDV) viruses, we generated lentiviral pseudotyped viruses (PVs) expressing the hemagglutinin-esterase fusion (HEF) glycoprotein from ICV (C/Minnesota/33/2015) and IDV (D/Swine/Italy/199724-3/2015, D/Bovine/France/5920/2014, and D/Bovine/Ibaraki/7768/2016). The production of these PVs was optimised using different amount of human airway trypsin-like (HAT) protease to enhance HEF maturation, and the transduction efficiency was evaluated in multiple cell lines. Using these PVs, we established a pseudovirus-based microneutralisation (pMN) assay to measure neutralising antibody responses and adapted an esterase activity assay to evaluate PV. Specific antisera neutralised PVs but failed to inhibit esterase activity. These findings confirm that ICV and IDV PVs provide a scalable, sensitive, and safe tool for antiviral screening, and sero-epidemiological research.

immunology↗

bioRxiv2024

A systematic review quantifying host feeding patterns of Culicoides species responsible for pathogen transmission

Culicoides biting midges are significant vectors of various pathogens, impacting both human and animal health globally. Understanding their host feeding patterns is crucial for deepening our understanding of disease transmission dynamics and developing effective control strategies. While several studies have identified the sources of blood meals in Culicoides, a quantitative synthesis of their host preferences and the factors influencing these behaviours is lacking. A systematic literature search focused on gathering data on (1) host selection and (2) host preference. For reviewing host selection we focused on studies reporting the identification of blood meal sources in individual Culicoides. When reviewing host preference we focused on studies comparing the number of Culicoides caught on or nearby different host species at the same location. Analysis revealed that some Culicoides species exhibit fixed host preferences, consistently feeding on specific hosts such as cattle and horses, while others display more opportunistic feeding behaviours. Notable variations were observed across different geographic regions. The findings indicate that host availability significantly influences Culicoides feeding patterns. This study highlights the complexity of host selection in Culicoides biting midges, which has implications for disease transmission. The variability in feeding behaviours underscores the need for regional assessments to inform targeted vector control strategies.

pathology↗

bioRxiv2024

Modelling the influence of climate and vector control interventions on arbovirus transmission

Most mathematical models that assess the vectorial capacity of disease-transmitting insects typically focus on the influence of climatic factors to predict variations across different times and locations, or examine the impact of vector control interventions to forecast their potential effectiveness. We combine features of existing models to develop a novel model for vectorial capacity that considers both climate and vector control. This model considers how vector control tools affect vectors at each stage of their feeding cycle and incorporates host availability and preference. Applying this model to arboviruses of veterinary importance in Europe, we show that African horse sickness virus (AHSV) has a higher peak predicted vectorial capacity than bluetongue virus (BTV), Schmallenberg virus (SBV) and epizootic haemorrhagic disease virus (EHDV). However, AHSV has a shorter average infectious period, due to high mortality, therefore AHSVs overall basic reproduction number is similar to BTV. A comparable relationship exists between SBV and EHDV, with both viruses showing similar basic reproduction numbers. Focusing on AHSV transmission in the UK, insecticide-treated stable netting is shown to significantly reduce vectorial capacity of Culicoides even at low coverage levels. However, untreated stable netting is likely to have limited impact. Overall, this model can be used to consider both climate and vector control interventions either currently utilised or for potential use in an outbreakand could help guide policy makers seeking to mitigate the impact of climate change on disease control. Author summaryIn our study, we developed an advanced mathematical model that integrates the influences of climate and vector control strategies to predict the transmission of arboviruses. This is then used to highlight the increase in vectorial capacity African horse sickness, bluetongue, epizootic haemorrhagic disease and Schmallenberg virus, which are transmitted by the Culi-coides species, in a European climate over the last 50 years. Our research provides valuable insights into how strategic use of insecticide-treated netting, even at low coverage levels, can substantially reduce the transmission potential of African horse sickness virus. This model offers a powerful tool for policymakers and health professionals, aiding in the formulation of more effective vector management strategies that could mitigate the impact of these diseases, especially in the context of changing global climates. This approach not only enhances our understanding of vector-borne disease dynamics but also supports the development of targeted interventions and prevent outbreaks.

ecology↗

bioRxiv2021

A novel bivalent DNA vaccine encoding both spike protein receptor-binding domain and nucleocapsid protein of SARS-CoV-2 to elicit T cell and neutralising antibody responses that cross react with variants

Although the efficacy of vaccines targeting SARS-CoV-2 is apparent now that the approved mRNA and adenovirus vector vaccines are in widespread use, the longevity of the protective immune response and its efficacy against emerging variants remains to be determined. We have therefore designed a DNA vaccine encoding both the SARS-CoV-2 spike receptorbinding domain ( RBD) and nucleocapsid proteins, the latter of which is highly conserved amongst beta coronaviruses. The vaccine elicits strong pro-inflammatory CD4+ Th1 and CD8+ T-cell responses to both proteins in mice and rats, with responses being significantly enhanced by fusing the nucleocapsid sequence to a modified Fc domain. We have shown that the vaccine also stimulates high titre antibody responses to RBD in mice that efficiently neutralise in pseudotype and live virus neutralisation assays and show cross reactivity with spike proteins from the variants B.1.1.7 (Alpha), B.1.351 (Beta) and B.1.617.2 (Delta). The vaccine also showed good protection in a viral challenge model in ACE2 receptor transgenic mice. This DNA platform can be easily adapted to target variant proteins and we show that a vaccine variant encoding the Beta variant sequence stimulates cross-reactive humoral and T cell responses. These data support the translation of this DNA vaccine platform into the clinic, thereby offering a particular advantage for rapidly targeting emerging SARS-CoV-2 variants.

immunology↗