Host defenses in experimental rickettsialpox: resistance of C3H mouse sublines.

: Eight sublines of C3H mice were tested for their resistance to lethal infection with Rickettsia akari,. strain Kaplan. C3H/HeJ mice were unique in their susceptibility to approximately one plaque-forming unit of rickettsiae. This lack of resistance is apparently due to a mutation in the mouse strain which occurred after 1950.