It’s a common, straightforward idea in science: When a viral, bacterial, or parasitic pathogen sneaks its way into a host and tries to infect cells, the immune system detects its presence and mounts a counterattack.
However, Harvard Medical School gastroenterologist Jonathan Kagan published a hypothesis paper in Science last week (January 26) that flips that idea on its head. In the paper, which has been downloaded over 9,000 times as of this article’s publication, Kagan asserts that the pattern recognition receptors (PRRs) that induce an immune response are not activated by the pathogens themselves. Instead, they respond to pathogen-associated molecular patterns (PAMPs), which are ligands such as short strands of genetic material or degraded cell wall proteins that are only released when the infectious agent has made an error, such as performing a low-fidelity genomic replication or dying as a result of a maladaptive or untidy mutation. By contrast, successful ...
