Dynamic model visualizing the process of viral plaque formation.

Understanding the concept of viral plaque and the process of viral plaque formation is essential for navigating viral biology and grasping the foundations of key laboratory methods in virology. Plaque assays are utilized routinely in Microbiology and Virology teaching laboratories to quantify viruses and as a tool to introduce and/or reinforce the technique of serial dilutions (2). The hands-on model described here creates an opportunity for students to experience the process of viral plaque formation while engaging multiple senses and creating a lasting impression. After all, a loud pop in the classroom never fails to attract attention! In Microbiology and Virology courses viral plaques are often presented to students as the way one can visualize viruses/bacteriophages. A viral plaque is defined as a physical entity: “a clear area on a lawn of bacteria or a monolayer of cells, where viruses have destroyed the cells” or functionally; as “the progeny of one virus” (3). Both definitions are received well by students and help them to grasp the idea that counting plaques is essentially the same as counting viruses in their sample (assuming that one virus entering the cell is sufficient for productive infection). In contrast, many times the process of plaque formation itself remains obscure. Many students fail to appreciate that viral plaques are actually a “laboratory-made” phenomenon allowing us to observe and study the growth of lytic viruses. (No plaques are found in nature or liquid culture!) The latter often presents a challenge for the interpretation of experimental data related to viral growth and drug discovery using plaque reduction assay.