Despite the fact that CypA is packaged in the viral particle from the infected cell, which could suggest that it plays a role at the level of the producer cells, it has been shown that it is the interaction between CA and the CypA molecules present in the target cells to be the major determinant for the effect exerted by CypA on HIV-1 infection (Hatziioannou et al., 2005). Here, PPIA is linked to HIV-1 infection.