Human immunodeficiency virus type 1 Env with an intersubunit disulfide bond engages coreceptors but requires bond reduction after engagement to induce fusion.
Abrahamyan LG, Markosyan RM, Moore JP, Cohen FS, Melikyan GB. Human immunodeficiency virus type 1 Env with an intersubunit disulfide bond engages coreceptors but requires bond reduction after engagement to induce fusion. J Virol. 2003 May; 77(10):5829-36.