Thiol-selective mechanism of HIV antigen conjugation with serum IgM, IgG, and IgA.

The effects of HIV antigen glycoproteins gp160, gp41, and gp36 on thiol-dependent specific (affinity) binding of serum IgM, IgG, and IgA with the corresponding antigens were determined by the formation of signal thiol-containing analytes (free nonprotein SH groups). Free nonprotein SH groups were not found in the reaction mixture, which indicated that HIV antigen glycoproteins blocked this process. The results suggest that the thiol-selective mechanism underlies in vitro conjugation of HIV antigen glycoproteins gp160, gp41, and gp36 with serum immunoglobulins. Previous studies showed that this mechanism of conjugation with immunoglobulins is not characteristic of other lymphotropic viruses (e.g., hepatitis B virus).