Abstract
The study of host-pathogen interactions has improved our understanding of both pathogenesis and the response of the host to infection, including both innate and adaptive responses. Neutrophils and macrophages represent the first line of innate host defense against any infection. The zebrafish is an ideal model to study the response of these cells to a variety of pathogens. Zebrafish possess both neutrophils and macrophages exhibiting similar defense mechanisms to their human counterparts. The transparency of zebrafish embryos greatly facilitates in vivo tracking of infection dynamics in a non-invasive manner at high-resolution using labelled pathogens, while immune cells can also be labelled transgenically to enable even more in-depth analysis. Here we describe a procedure for performing a bacterial infection assay in zebrafish embryos using fluorescently-labelled E. coli bacteria and demonstrate the monitoring and quantification of the infection kinetics. Of note, this procedure helps in understanding the functional role of genes that are important in driving the innate immune response.