The use of Multiplex Imaging and Spatial Transcript analysis in the preclinical evaluation of vaccines against diseases induced

Prof F. Javier Salguero Bodes, UK Health Security Agency (UKHSA), UK

The preclinical animal models of infectious diseases are a critical tool in the development of new vaccines and therapies previous to clinical trials and licensure. We have developed a large variety of animal models of mycobacterial infections, mostly tuberculosis (non-human primate, guinea pig, mouse, cattle) and other diseases induced by intracellular pathogens (leishmaniasis, melioidosis and viral infections). Accurate pathological analysis of tissue samples from the preclinical studies is of high importance to evaluate the efficacy, but also the safety of new candidate vaccines. The traditional pathological evaluation includes normally the analysis of H&E-stained sections and the presence of the pathogen by immunohistochemistry (IHC) or in situ hybridisation (ISH). However, a variety of modern tools have been developed recently to study “in depth” the immune responses against the pathogen and the cellular interactions “in situ” in the target organs. Multiplex Immunofluorescence (IF) linked to digital image analysis and AI tools is being used to analyse objectively and quantitatively the host-pathogen interactions, with a focus on the “neighbouring cells” in multicellular structures at the sites of infection or local immune responses. Another very important tool developed in the past few years is the transcript analysis in formalin-fixed paraffin-embedded (FFPE) material, giving a spatial dimension to the changes in the transcriptome in targeted cells and structures in tissues, applicable even to archived material. In this talk, we will review the use of these modern techniques in selected projects involving a variety of intracellular pathogens.