Expression of CypA proteins with mutations in secondary site residues A25 and K27 in CypA-null Jurkat cells restored their permissiveness to infection by wild type HIV-1 close to the level observed for wild type CypA, while the destabilized mutant CypA K30D showed partial enhancement of infectivity (see also Additional file 1: Figure S4). The gene discussed is PPIA; the disease is infection.