ITIH4 and HIV-1 infection: This result suggests that preincubation of 2DLT with HIV-1 may trigger the increased exposure of the gp41 PFI, because of the increased binding of D1D2 domain in 2DLT with gp120 on virions, resulting in the increased binding of its T1144 domain to the exposed gp41 PFI and enhanced inhibition of HIV-1 infection.