"No way did I want my partner to be infected," she said.
According to the charge sheet, Benaissa had sex on five occasions between 2000 and 2004 with three people and did not tell them she was infected, even though she had known about it since 1999.
One of the three had since been confirmed as being infected with the HIV virus, which causes Aids, prosecutors had said in February.
Benaissa was arrested in April 2009 and kept in custody for 10 days - a move that a German Aids awareness group criticised as disproportionate.
If convicted she faces between six months and 10 years in prison.
A verdict is due on on August 26.