The effect of human immunodeficiency virus type 1 (HIV-1) gp41 variability on antibody detection.

To determine whether genetic variability influences the ability to detect antibody, nine gp41 ectodomain recombinant proteins from human immunodeficiency virus type 1 (HIV-1) CRF07_BC, CRF01_AE and subtype B' were expressed in a bacterial expression system and purified. An indirect sandwich ELISA was developed with individual purified recombinant proteins. Plasma samples from 26 individuals infected with HIV-1 of different subtypes and four samples from the 1st international antibody reference panel were tested against each recombinant protein by ELISA. Heat-map and two-dimensional hierarchical clustering methods revealed that ELISA reactivity against antigens derived from the same subtypes clustered together. This suggests a similar reactivity pattern among infections of the same subtype, and thus the antigenicity of gp41 recombinant proteins may vary depending on the subtype, and subtype-related serotypes may exist among these antigens. Using association analysis methods, eight signature sites related to the subtype-specific reactivity patterns were identified. This study provides valuable information for the development of diagnostic assays with the ability to detect broadly cross-reactive antibodies induced by infection with different HIV-1 subtypes.