Group A Streptococcus (GAS) is responsible for infections ranging from “strep throat” to necrotizing fasciitis, aka the “flesh-eating disease”, a severe and invasive condition that has seen a marked increase in incidence in the past 30 years. The increase has been pinned on a single clone of the M1T1 serotype, which undergoes a genetic “switch” in the body to a hypervirulent state that allows it to move into the bloodstream.
In a study just released by mBio, researchers identify the virulence factors GAS needs to make the switch. Only three factors are needed: nuclease Sda1, M1 protein, and hyaluronic acid capsule together comprise a quorum of cooperative virulence factors that promote resistance to traps set by the immune system.
