HIV-1 p24 Antibody: The human immunodeficiency virus type 1 (HIV-1) particle consists of an envelope, a core and the region between the two termed matrix. The HIV-1 Gag protein is a late structural protein that contains four proteins: matrix (p17), capsid (p24), nucleocapsid (p7) and the p6 protein. The p24 is the major capsid protein of the virus and has been used in clinical trials as one of the components of the HIV-1 vaccine because of the high degree of sequence conservation between different strains.