Biology subjects

Assogba, B. D.

Publications and source records attributed to Assogba, B. D..

6 recordsLinked to original sources

bioRxiv2026

Epigenetic Regulation of Stable SARS-CoV-2 RBD-sfGFP Expression in Primary Human Splenic Fibroblasts

BackgroundRecombinant expression of the SARS-CoV-2 receptor-binding domain (RBD) is essential for vaccine development, serological diagnostics, and mechanistic studies. Primary human fibroblasts offer physiologically relevant protein folding and post-translational modification, yet their short lifespan limits scalable production. We used an immortalized human splenic fibroblast cell line to stably express RBD-sfGFP for longitudinal characterization and downstream studies. MethodsImmortalized human primary splenic fibroblasts were transfected by electroporation with a plasmid encoding SARS-CoV-2 RBD fused to superfolder GFP (sfGFP), with a neomycin resistance cassette (neoR) for G418 selection. Four independent G418-resistant cultures (n=4), designated HPSF-IM-RBD-BHSKPU T1-T4, were established from distinct selection flasks. Based on previous screenings, two cultures (T1, T3) were monitored for 98 days (14 passages, P1-P14); two cultures (T2, T4) were monitored for 42 days (6 passages, P1-P6). RBD-sfGFP expression was assessed by fluorescence microscopy at 7-day intervals. For each timepoint, 2 fields were imaged and analyzed for relative fluorescence intensity (normalized to global maximum = 100%) and mean fluorescence intensity (MFI, normalized to global maximum = 100%). Coefficient of variation (CV), linear regression, and Pearson correlation were calculated. ResultsAll four cultures exhibited robust GFP fluorescence, confirming stable transgene retention. Expression ranking: T1 (93.1% +/- 3.6%) > T3 (89.2% +/- 3.4%) > T2 (84.2% +/- 3.2%) > T4 (79.7% +/- 3.9%). Long-term cultures T1 and T3 retained [~]100% of Day 7 signal at Day 98 (T1: 100.7%; T3: 100.0%). Expression exhibited passage-dependent oscillation rather than progressive silencing. CV increased over time in T1 (1.5% -> 8.5%), indicating growing inter-cellular heterogeneity. A strong positive correlation between fluorescence and MFI (Pearson r = 0.823, p = 7.44 x 10-11) suggested coherent population-level regulation. ConclusionsHPSF-IM-RBD-BHSKPU cells stably retain RBD-sfGFP expression for over 3 months, validating their utility as a recombinant protein production platform. However, oscillatory dynamics and increasing heterogeneity are consistent with position-effect variegation at distinct integration loci. Consequently, early passages (P1-P4) are optimal for applications requiring maximal uniformity. Ultimately, these cells provide a practical tool for RBD production and a valuable model for studying epigenetic regulation of transgene expression in human primary fibroblast backgrounds.

bioengineering↗

bioRxiv2025

Garlic-Derived Allicin Modulates Expression of the SARS-CoV-2 Spike Receptor-Binding Domain in Human Splenic Fibroblasts

Allicin, a natural sulfur-rich compound, is formed when garlic is crushed or chopped. It has been used for centuries as a natural defence against bacteria and fungi. However, we do not fully understand how well it works against viruses, such as SARS-CoV-2. In this study, we investigated the effect of allicin on the expression of the SARS-CoV-2 receptor-binding domain of the spike protein in human primary splenic fibroblasts. These cells were transfected with a plasmid encoding RBD-S protein fused to a superfolder green fluorescent protein (sfGFP), a bright, stable marker. When cells were treated with 50{square}{micro}M allicin, either 30 min before or 6 h after transfection, a pronounced drop in fluorescence was observed, indicating reduced spike protein expression. Interestingly, the cell morphology, growth, and behavior remained normal, indicating that allicin could minimize spike protein levels without being toxic to the cells. These results open the door to the use of allicin as a gentle, natural antiviral agent and raise critical questions regarding the regulation of protein expression after transcription. Further research is required to understand these effects better.

cell biology↗

bioRxiv2025

Antibiotic Resistance in Staphylococcus aureus: Effects of Quorum Sensing Inhibition and DNA Fragmentation

BackgroundAntimicrobial resistance (AMR) is a global crisis, causing 2.8 million infections and 35,000 deaths annually. Staphylococcus aureus is mainly responsible for causing these challenging infections through biofilm formation and the action of efflux pumps. A limited number of studies on Hop (Humulus lupulus) have shown its potential to inhibit quorum sensing in pathogenic bacteria. ObjectiveTherefore, a novel treatment approach was used in this study, which investigated Hops {beta}-acids, particularly the combination of colupulone and n+adlupulone, as well as in combination with fluoroquinolone antibiotics ciprofloxacin and ofloxacin. As ciprofloxacin remains a highly effective antibiotic against Staphylococcus aureus but resistance can develop, and ofloxacin exhibits naturally higher resistance in S. aureus, this study hypothesized that combining Hop (containing colupulone & n+adlupulone) with the two antibiotics separately would result in a greater reduction in biofilm growth of S. aureus compared to their individual potency levels. MethodsAntimicrobial activity was assessed using disk diffusion assays and minimum inhibitory concentration for biofilms at multiple concentrations through 2-fold serial dilutions. ResultsOur data demonstrate that Hop-derived {beta}-acids possess direct antimicrobial activity and when combined with the fluoroquinolone antibiotics, exhibit additive or synergistic effects by acting on different targets in Staphylococcus aureus. ConclusionsThis study provides insight into how natural products can potentially mitigate the development of resistance to antibiotics like ciprofloxacin in the highly pathogenic bacterium S. aureus. It also highlights how adding natural compounds could improve drug effectiveness. Therefore, this demonstrates the potential of natural compounds and antibiotics like ofloxacin, which are known to be ineffective against S. aureus. It offers a promising natural-conventional hybrid approach to addressing antimicrobial resistance.

microbiology↗

bioRxiv2025

COVID-19 in Space: Possible Health Risks and Preparedness Guidelines

Background The COVID-19 pandemic of 2020 resulted in over 705 million infections and more than 7 million deaths worldwide. The virus primarily spreads through aerosol droplets released during breathing, coughing, or sneezing, leading to symptoms ranging from mild fever and cough to severe outcomes, including death. Given the high risk associated with COVID-19, understanding its behaviour in diverse geographical and environmental conditions is critical. Space exploration and tourism represent an emerging industry, projected to reach a market value of $1.8 trillion. With numerous space missions planned by space agencies such as NASA, SpaceX, and ISRO, it is vital to address potential health risks for astronauts and space tourists. ObjectiveWith the expansion of human exploration into space, there is an urgent need to assess the risks posed by COVID-19 in extraterrestrial environments. This study reviews existing literature on airborne infections in space, identifies key knowledge gaps, and enhances preparedness for potential COVID-19 outbreaks during space missions. MethodsA systematic literature review was conducted to identify studies examining airborne infectious diseases in space and their health effects under microgravity. Databases searched included PubMed and NASAs Open Data Portal. To compare these findings with Earth-based data, additional systematic reviews were performed to analyze the known effects of these diseases on Earth, using Pathogen Safety Data Sheets. A separate systematic review was conducted using PubMed to explore similarities between COVID-19 and the selected airborne infectious diseases. Using a comparative approach, disease effects observed on Earth and in space were analyzed to predict COVID-19s potential behavior in microgravity. Existing guidelines for managing airborne diseases in space and on Earth were reviewed and compared to develop a set of preparedness recommendations for COVID-19 in space. ResultsThe airborne infectious diseases occurring in space found in this study include Aspergillus fumigatus, Beauveria bassiana, Epstein-Barr Virus (EBV), Escherichia coli, Klebsiella pneumoniae infections, Pseudomonas aeruginosa, Roseolovirus (Human Herpesvirus 6 & 7), Salmonella Typhimurium infection, Serratia marcescens infection, Staphylococcus aureus, Staphylococcus epidermidis, and Varicella-Zoster Virus (VZV). The relationship between the aforementioned diseases and COVID-19 was used in regard to theorizing the effects of COVID-19 in space. Six Tentative effects of COVID-19 in a microgravity environment could be theorized in this study. Along with that, recommendations to improve the current space travel health guidelines have also been referred to. ConclusionThe results of this study will change the course of human space exploration by assisting in the protection of space travelers and guiding the development of new designs for spacecraft that include extra safety features.

microbiology↗

bioRxiv2025

Optimizing Transfection Efficiency in Primary Human Splenic Fibroblast Cells

Transfection, a fundamental molecular biology technique, is crucial in introducing foreign DNA into cells. Despite its pivotal importance, mastering this technique remains a formidable challenge. In this study, we employed the calcium phosphate reagent and conducted a systematic exploration through time-dependent experiments to assess its impact on human primary splenic fibroblast cells (HSFC). The results precisely delineate optimal time frames for achieving enhanced transfection efficiency, offering conclusive evidence for the efficacy of calcium phosphate in transient transfection within the cells. The data significantly advances our comprehension of HSFC reactions, contributing to refining transfection methodologies with broader implications for biomedical applications.

cell biology↗

bioRxiv2022

Detection and Role of Feline Apolipoprotein B mRNA-editing Enzyme Catalytic Polypeptide Subunit 3G-Like Protein in Feline Cells and Tissues

The innate host defence system is designed to resist pathogenic microorganism infections. Despite the compelling scientific evidence, our understanding of the full potential of the mechanism is still unclear due to the complex interactions between hosts and invaders. We previously reported latency in cat mucosal infected with low-dose cell-associated feline immunodeficiency virus (102 and 103 infected cells). Here we investigated the expression of Apolipoprotein B mRNA-editing enzyme catalytic subunit 3G (APOBEC3G or A3G) in feline cells and tissues and whether its presence antagonizes the viral pre-integration complex resulting in partial or complete FIV latency. Total RNA and protein lysates were collected from cell lines, blood, and tissue samples. Real-time RT-PCR and western blot assays were used to quantify fA3G-like protein in cats exposed to high versus low-dose cell-associated FIV. We consistently detected fA3G-like protein in mock T-cell lines (E-CD4+, MYA-1, Crandell feline kidney cells) and primary bone marrow-derived macrophages with variable expressions in feline peripheral blood mononuclear cells (PBMC). In addition, the fA3G-like protein was found to interact with FIV group-specific antigen (Gag) protein through immunoprecipitation assays. The protein expression was utterly abrogated following FIV infection. However, in lytic FIV infection (in vivo), fA3G-like protein decreased in early post-infection, whereas latently infected cats showed stable expression. These data are the first report of the fA3G-like protein expression in felines and its abrogation in lytic but not in latent FIV-infected individuals. These results might provide new insight into the role of fA3G-like protein in the host defence mechanism against retrovirus infections.

cell biology↗