Biology subjects

Biagini, G. A.

Publications and source records attributed to Biagini, G. A..

3 recordsLinked to original sources

bioRxiv2026

Bloodstream-associated Salmonella Typhimurium and Enteritidis iNTS pathovariants hyper-replicate in human macrophages

Invasive non-typhoidal Salmonella (iNTS) are a major cause of bloodstream infections in sub-Saharan Africa, yet the host-pathogen interaction mechanisms remain poorly understood. Here, we developed and optimised a human macrophage infection model based on PMA-differentiated THP-1 cells to investigate infection dynamics of clinically relevant Salmonella Typhimurium and Salmonella Enteritidis strains. We compared intracellular survival and replication of gastroenteritis-associated and bloodstream-associated pathovariants, including S. Typhimurium ST313 Lineage 2, the novel S. Typhimurium ST313 Lineage 3 and the understudied S. Enteritidis Central/Eastern African (CEAC) clades. Our results reveal that the CEAC S. Enteritidis and ST313 S. Typhimurium iNTS pathovariants hyper-replicate within host cells, compared to global epidemic isolates. The cellular model achieved robust pro-inflammatory polarisation of human macrophages, while revealing limitations in modelling macrophage plasticity. Overall, this work defines clear differences in intracellular behaviour of Salmonella pathovariants and establishes a robust experimental framework for future studies on invasive disease pathogenesis and therapeutic interventions that target iNTS bacteria.

microbiology↗

bioRxiv2025

Dynamic Culture Improves the Predictive Power of Bronchial and Alveolar Airway Models of SARS-CoV-2 Infection

Human in vitro lung models represent advanced tools for studying respiratory infections, particularly those caused by emerging respiratory pathogens. Despite scientific advances, vaccine and therapeutics pre-clinical development has yet to fully adopt human-relevant testing platforms due in part to a lack of validation. In this study, we characterised how static and dynamic flow culture conditions influence microphysiological systems (MPS) generated using primary bronchial and alveolar epithelial cells. We assessed epithelial structure, functional differentiation, and infection dynamics. This study represents the first direct comparison of how dynamic flow and endothelial co-culture influence viral tropism, replication kinetics, and host responses across anatomically distinct regions of the respiratory tract in vitro. Dynamic flow promoted formation of more physiologically relevant tissue architecture, pseudostratified bronchial epithelium and alveolar sac-like structures, with enhanced epithelial differentiation and retention of region-specific cell phenotypes at the transcriptomic level. Both static and dynamic flow models demonstrated responsiveness to inflammatory stimuli (poly(I:C), LPS), producing distinct, tissue-specific cytokine profiles and supporting infection with multiple SARS-CoV- 2 variants. Differences in infection efficiency, viral replication, and host gene expression were observed between variants, with dynamic flow models offering enhanced sensitivity and resolution. In alveolar tissues, dynamic flow increased infection efficiency and reduced variability, enabling more robust and consistent transcriptional responses. This facilitated the identification of interferon signalling pathways as key targets of the host response. Among the variants tested, Delta induced the most extensive tissue damage and strongest transcriptional response, whereas Omicron BA.5 exhibited greater infectivity in alveolar models compared to earlier variants. Our findings demonstrate that dynamic flow MPS more closely replicate human lung tissue architecture and cellular diversity, while also enhancing the predictive power and clinical relevance of airway models for ex vivo studies of SARS-CoV-2 infection. These improvements strengthen the reliability of data generated for the study of host-pathogen interaction studies and support the use of dynamic systems for evaluating novel anti-infectives, immunomodulators, and functional characterisation of immune sera generated by next-generation vaccines. Collectively, our results highlight the value of integrating dynamic in vitro models into preclinical pipelines for emerging respiratory pathogens.

microbiology↗

bioRxiv2021

Quantitation of tizoxanide in multiple matrices to support cell culture, animal and human research.

Currently nitazoxanide is being assessed as a candidate therapeutic for SARS-CoV-2. Unlike many other candidates being investigated, tizoxanide (the active metabolite of nitazoxanide) plasma concentrations achieve antiviral levels after administration of the approved dose, although higher doses are expected to be needed to maintain these concentrations across the dosing interval in the majority of patients. Here an LC-MS/MS assay is described that has been validated in accordance with Food and Drug Administration (FDA) guidelines. Fundamental parameters have been evaluated, and these included accuracy, precision and sensitivity. The assay was validated for human plasma, mouse plasma and Dulbeccos Modified Eagles Medium (DMEM) containing varying concentrations of Foetal Bovine Serum (FBS). Matrix effects are a well-documented source of concern for chromatographic analysis, with the potential to impact various stages of the analytical process, including suppression or enhancement of ionisation. Therefore, a robustly validated LC-MS/MS analytical method is presented capable of quantifying tizoxanide in multiple matrices with minimal impact of matrix effects. The validated assay presented here was linear from 15.6ng/mL to 1000ng/mL. Accuracy and precision ranged between 102.2% and 113.5%, 100.1% and 105.4%, respectively. The presented assay here has applications in both pre-clinical and clinical research and may be used to facilitate further investigations into the application of nitazoxanide against SARS-CoV-2.

pharmacology and toxicology↗