PPIA and infection: Whereas we cannot rule out an effect of CypA-DsRed on the stability of the HIV-1 core, as has been reported for monomeric CypA [33,54,58,60], the lack of a negative effect on HIV-1 infectivity when expressed in producer or target cells, along with the existence of apparently intact post-fusion cores (that shed CypA-DsRed upon CsA addition) in the cytoplasm several hours after synchronized infection, show the utility of CypA-DsRed as a marker for HIV-1 uncoating.