Spontaneous activation of human immunodeficiency virus type 1 in an immunotoxin-resistant variant T cell line

We have previously used immunotoxins to select for HIV-1 variant cells that transcribe HIV at extremely low levels and fail to produce HIV proteins. Further observation of one of these variants (E9) demonstrated spontaneous in vitro activation of HIV production. The mechanism of activation is different from that of U1 and ACH-2, two other cell lines that can be activated to express HIV in vitro.