Analysis of cell migration during human cytomegalovirus (HCMV) infection

Previous studies have demonstrated that dendritic cells (DC), macrophages (Mφ), and their precursors monocytes are susceptible to infection by human cytomegalovirus (HCMV) in the natural host as well as in vitro. Due to their proficient ability to take up and present antigens to the lymphocytes these cells are also called antigen presenting cells (APC) and represent a crucial component that HCMV needs to disable in order to limit the antiviral immune reaction. It is well known that cell trafficking is an essential property of APC. Monocytes and DC are usually regarded as very motile cells and their trafficking properties through the blood vessels, the peripheral tissues, and the lymphoid organs are intensively studied. On the other hand, although often considered a resident population, Mφ are also motile and can actively migrate into areas of infection, inflammation, and tissue regeneration. The movements of monocytes, DC, and Mφ require a tight control that is mainly assured by chemokines (CK) and their receptors. While it is quite common to study the expression of chemokine receptors by flow cytometry, methods for the investigation of the chemokine receptor functionality are less widespread. In this chapter, we describe different techniques that can help in the analysis of cell migration in response to CK. Cell polarization assays measure the rapid morphological changes that follow the chemokine receptors' engagement by their ligands. Actin polymerization assays measure the subsequent conversion of globular units of actin into dynamic filaments. Finally, chemotaxis assays quantify the cell movements along a CK gradient.