SOD Enzymes and Microbial Pathogens: Surviving the Oxidative Storm of Infection

Since oxygen appeared in the biosphere some 3-5 billion years ago, all organisms have had to deal with the hazards of potentially damaging reactive oxygen species (ROS), such as superoxide, hydrogen peroxide, and hydroxyl radical. Like all organisms, pathogenic microbes produce ROS as byproducts of aerobic metabolism, but the burden of ROS is magnified when these microbes confront the oxidative burst of the host. As part of the innate immune response, macrophages and neutrophils attack invading microbes with toxic superoxide 1. To counteract this attack, some microbial pathogens express superoxide dismutase enzymes (SOD).