I believe most (if not all) of the top strat houses interview without regard to nationality. They want to hire the best, regardless of whether they're American, European, Asian, or Martian. H-1B visas are automatically sponsored if you are extended an offer, and the ones know sponsor for green cards as well after you get promoted to the next level.I'm not sure whether the Big 4 or the HR boutiques have the same policy. Good luck.