SUMMARY: The introduction talks about the different types of CRISPR-Cas systems and the first section explains how these CRISPR systems were used in the past (mostly to see the genotypic relationship between bacteria). It wasn’t until 2013 that scientists discovered CRISPR was a type of adaptive immune system in bacteria (a branch of the immune system that remembers past pathogens). The rest of the sections talk about different ways that researchers have caused CRISPR-Cas system genes to be down regulated and up regulate; they realized that this system helped bacteria become more virulent by: producing more biofilm, live inside a macrophage or amoeba, avoid the innate immune system, resist chemicals produced by the immune system to kill bacteria, and many other characteristics.
LESSON COMMENTS: This article can be used when teaching a unit on the immune system. Students will gain a solid understanding of the innate and adaptive immune system. On page 82, the last paragraph mentions double stranded RNA; this is a good section to introduce PAMPs (pathogen associated molecular patterns) and how they are the target of the innate immune system. On the following page, the article explains the way this particular bacteria produces less dsRNA and thus is able to avoid TLRs (TLR-2, specifically). There are many other examples like this in this article, using bacteria that students have heard of (Y. pestis, for instance). This may even be a good way to collaborate with a history class, combining the science of the pathogenicity of the black plague with the historical events that occurred because of its spread.
For middle school students, this is a good article to introduce them to what CRISPR is (the beginning of the paper explains what the CRISPR-Cas system’s function is in the bacteria as well as the applications of it in gene editing).
Louwen, R., Staals, R. H., Endtz, H. P., van Baarlen, P., & van der Oost, J. (2014). The role of CRISPR-Cas systems in virulence of pathogenic bacteria. Microbiology and molecular biology reviews : MMBR, 78(1), 74-88.