Wild type CypA and CypA mutants A25D, A25K, K27A, K27D, P29K and K30D could be expressed in the CypA-null cells at near or above endogenous levels (Fig. 5b) using lentiviral vectors, which inhibited HIV-1 A92E infection and thus restored the CsA dependence to the same extent for all variants (− CsA/+ CsA infection ratio < 0.1, Fig. 5a). The gene discussed is PPIA; the disease is infection.