Group-specific antigen

Group-specific antigen (gag) is the genetic material that codes for the core structural proteins of a retrovirus.

gag in HIV
gag proteins are encoded by the gag gene, and provide structural elements of the virus.


 * gag = p24 + p6 + p7 + p17

p24 makes up the viral capsid. When a Western blot test is used to detect HIV infection, p24 is one of the three major proteins tested for, along with gp160 (= gp120 + gp41). p6 and p7 are included in the nucleocapsid. p17 provides a protective matrix (a protein that forms a scaffold during virion assembly).