A seal structure for a gas turbine engine, comprising: a vane (202, 302, 412); a blade outer air seal (208, 318, 418) adjacent to the vane (202, 302, 412); and a brush seal (100, 300, 400) disposed in a cavity (104, 304, 404) defined at least partially by a first surface of the blade outer air seal (108, 308, 408) and a second surface of the vane (106, 306, 406), the brush seal (100, 300, 400) comprising: a bristle pack (120, 320, 420), and a backing plate (122, 322, 422) coupled to the bristle pack (120, 320, 420); characterized in that: the backing plate (122, 322, 422) contacts the first surface of the blade outer air seal (108, 308, 408) and the second surface of the vane (106, 306, 406); and the first surface of the blade outer air seal (108, 308, 408) comprises a radial surface of the blade outer air seal (108, 308), the second surface of the vane (106, 306, 406) comprises an axial surface of the vane (106, 306), and the bristle pack (120, 320) contacts both the radial surface of the blade outer air seal (108, 308) and the axial surface of the vane (106, 306); or the first surface of the blade outer air seal (108, 308, 408) comprises a first radial surface of the blade outer air seal, the second surface of the vane (106, 306, 406) comprises second radial surface of the vane, and the bristle pack contacts both the first radial surface of the blade outer air seal and the second radial surface of the vane. a vane (202, 302, 412); a blade outer air seal (208, 318, 418) adjacent to the vane (202, 302, 412); and a brush seal (100, 300, 400) disposed in a cavity (104, 304, 404) defined at least partially by a first surface of the blade outer air seal (108, 308, 408) and a second surface of the vane (106, 306, 406), the brush seal (100, 300, 400) comprising: a bristle pack (120, 320, 420), and a backing plate (122, 322, 422) coupled to the bristle pack (120, 320, 420); characterized in that: the backing plate (122, 322, 422) contacts the first surface of the blade outer air seal (108, 308, 408) and the second surface of the vane (106, 306, 406); and the first surface of the blade outer air seal (108, 308, 408) comprises a radial surface of the blade outer air seal (108, 308), the second surface of the vane (106, 306, 406) comprises an axial surface of the vane (106, 306), and the bristle pack (120, 320) contacts both the radial surface of the blade outer air seal (108, 308) and the axial surface of the vane (106, 306); or the first surface of the blade outer air seal (108, 308, 408) comprises a first radial surface of the blade outer air seal, the second surface of the vane (106, 306, 406) comprises second radial surface of the vane, and the bristle pack contacts both the first radial surface of the blade outer air seal and the second radial surface of the vane. a bristle pack (120, 320, 420), and a backing plate (122, 322, 422) coupled to the bristle pack (120, 320, 420); characterized in that: the backing plate (122, 322, 422) contacts the first surface of the blade outer air seal (108, 308, 408) and the second surface of the vane (106, 306, 406); and the first surface of the blade outer air seal (108, 308, 408) comprises a radial surface of the blade outer air seal (108, 308), the second surface of the vane (106, 306, 406) comprises an axial surface of the vane (106, 306), and the bristle pack (120, 320) contacts both the radial surface of the blade outer air seal (108, 308) and the axial surface of the vane (106, 306); or the first surface of the blade outer air seal (108, 308, 408) comprises a first radial surface of the blade outer air seal, the second surface of the vane (106, 306, 406) comprises second radial surface of the vane, and the bristle pack contacts both the first radial surface of the blade outer air seal and the second radial surface of the vane. the backing plate (122, 322, 422) contacts the first surface of the blade outer air seal (108, 308, 408) and the second surface of the vane (106, 306, 406); and the first surface of the blade outer air seal (108, 308, 408) comprises a radial surface of the blade outer air seal (108, 308), the second surface of the vane (106, 306, 406) comprises an axial surface of the vane (106, 306), and the bristle pack (120, 320) contacts both the radial surface of the blade outer air seal (108, 308) and the axial surface of the vane (106, 306); or the first surface of the blade outer air seal (108, 308, 408) comprises a first radial surface of the blade outer air seal, the second surface of the vane (106, 306, 406) comprises second radial surface of the vane, and the bristle pack contacts both the first radial surface of the blade outer air seal and the second radial surface of the vane.