Use of TrpE/Gag fusion proteins to characterize immunoreactive domains on the human immunodeficiency virus type 1 core protein

The human immunodeficiency virus (HIV) p24 core protein is one of the most immunogenic of HIV structural proteins. Infected individuals develop high titers of antibodies against p24 early in infection, which makes anti-p24 antibodies important serological markers. However, despite the clinical importance of the anti-p24 response, no systematic study to characterize the antigenic domains on the p24 protein has been reported. We report here on the use of 12 overlapping fragments of the HIV type 1 p24 protein, synthesized in bacteria as TrpE/Gag fusion proteins, to identify at least two and possibly three antigenic domains on the p24 protein. In addition, we note that different HIV-seropositive sera exhibited different patterns of reactivity with the p24 domains presented on our fusion proteins.