Biology subjects

Priestman, M.

Publications and source records attributed to Priestman, M..

2 recordsLinked to original sources

bioRxiv2023

A BCG Skin Challenge Model for Assessing TB Vaccines

Controlled Human infection models (CHIM) are valuable tools for assessing relevant biological activity in vaccine candidates, with the potential to accelerate Tuberculosis vaccine development into the clinic. Tuberculosis infection poses significant constraints on the design of a CHIM using the causative agent Mycobacterium tuberculosis. As a safer alternative, we propose a challenge model using the attenuated vaccine agent Mycobacterium bovis BCG as a surrogate for Mycobacterium tuberculosis, and intradermal (skin) challenge as an alternative to pulmonary infection. We have developed a unique non-invasive imaging system based on fluorescent reporters to quantitatively measure bacterial load over time, thereby determining a relevant biological vaccine effect. We assessed the utility of this model to measure the effectiveness of two TB vaccines: the currently licenced BCG and a novel subunit vaccine candidate. To assess the efficacy of the skin challenge model a pharmacometric model was built describing the decline of fluorescence over time. The results show that vaccination is a statistically significant factor which reduced the fluorescence readout of both fluorophores. The higher decline in vaccinated mice correlated with bacterial burden in the lungs. This supports the fluorescence output from the skin as a reflection of vaccine induced functional pulmonary immune responses. This novel non-invasive approach allows for repeated measurements from the challenge site, providing a dynamic readout of vaccine induced responses over time. This BCG skin challenge model represents an important contribution to the ongoing development of controlled challenge models for Tuberculosis.

microbiology↗

bioRxiv2019

Size-dependent increase in RNA Polymerase II initiation rates mediates gene expression scaling with cell size

Cell size varies during the cell cycle and in response to external stimuli. This requires the tight coordination, or \"scaling\", of mRNA and protein quantities with the cell volume in order to maintain biomolecules concentrations and cell density. Evidence in cell populations and single cells indicates that scaling relies on the coordination of mRNA transcription rates with cell size. Here we use a combination of single-molecule fluorescence in situ hybridisation (smFISH), time-lapse microscopy and mathematical modelling in single fission yeast cells to uncover the precise molecular mechanisms that control transcription rates scaling with cell size. Linear scaling of mRNA quantities is apparent in single fission yeast cells during a normal cell cycle. Transcription rates of both constitutive and regulated genes scale with cell size without evidence for transcriptional bursting. Modelling and experimental data indicate that scaling relies on the coordination of RNAPII transcription initiation rates with cell size and that RNAPII is a limiting factor. We show using real-time quantitative imaging that size increase is accompanied by a rapid concentration independent recruitment of RNAPII onto chromatin. Finally, we find that in multinucleated cells, scaling is set at the level of single nuclei and not the entire cell, making the nucleus the transcriptional scaling unit. Integrating our observations in a mechanistic model of RNAPII mediated transcription, we propose that scaling of gene expression with cell size is the consequence of competition between genes for limiting RNAPII.

molecular biology↗