Title : Characterising the dendritic cell response to BCG using a bovine afferent lymphatic cannulation model and Single Cell RNA Seq
Abstract:
Vaccination is a key component in the control of animal pathogens that impact the livestock industry. However, deployable, efficacious vaccines remain unavailable for many prevalent diseases, particularly those requiring cell-mediated immunity, such as bovine tuberculosis (TB). In addition,the current ‘vaccinate and challenge’ approach offers little insight into why a candidate vaccine may fail. BCG is a live-attenuated form of Mycobacterium bovis, the causative agent of bovine TB, and is known to induce a strong Th-1 response associated with protective immunity. This project aimed to identify protective signatures associated with cell-mediated immunity in afferent lymphatic DC (ALDC) trafficking from BCG vaccination sites to the lymph node. To achieve this, we utilised a bovine afferent lymphatic cannulation model and collected pseudo-afferent lymph both pre- and 24h post- BCG vaccination, allowing us to perform analysis directly ex-vivo. ALDC were analysed by flow cytometry, single cell and bulk RNA-sequencing. We found three major populations of ALDC draining from the vaccination site: CD172a+ve DC, CD172a-ve DC, and Langerhans Cells. These major populations were divided into 10 sub-populations which exhibited differential gene expression in response to BCG, indicating that individual populations may have differing roles in response to mycobacteria. Pseudo-afferent lymph was also exposed to BCG in vitro, with the aim of using cultured ALDC as a novel way to screen vaccine candidates prior to animal studies.
