PHILADELPHIA (AP) -- Several schoolgirls allegedly abused at Oprah Winfrey's academy in South Africa and the talk-show host herself are expected to testify at an upcoming trial in Philadelphia.

The school's former headmistress is suing Winfrey for defamation over remarks Winfrey made during the 2007 scandal.

Winfrey said she had "lost confidence" in headmistress Nomvuyo Mzamane (num-VOO'-yo m-zah-MAH'-neez) and was "cleaning house from top to bottom." Mzamane says she had trouble finding a new job afterward.

The defamation case is headed for a two-week federal trial starting March 29. Lawyers were in court Friday to discuss witness lists and other last-minute details.

A dorm matron has been charged in South Africa with abusing six students.