FIG 4.

MT-WQ-IDL does not block the attachment of HIV-1 to cells expressing CD4 receptor but may interact with the CD4-triggered prehairpin intermediate of the HIV-1 gp41. (A, B) A washout assay was performed to determine whether MT-WQ-IDL (A) and heparin, a nonspecific HIV-1 attachment inhibitor (B), can block the attachment of HIV-1 to CD4-expressing cells (U87 CD4⁺ CCR5⁺ cells). (C) An HIV-1 Env-mediated cell-cell fusion washout assay was performed to determine the Env engagement of CD4 receptor in the MT-WQ-IDL-mediated inhibition of HIV-1 entry. Inhibition rates were as follows: MT-WQ-IDL alone without wash, 93.8%; MT-WQ-IDL alone with wash, 5.6%; sCD4 alone with wash, 30.6%; MT-WQ-IDL and sCD4 with wash, 87.1%. Error bars show standard deviations.