Human cyclophilin has a significantly higher affinity for HIV-1 recombinant p55 than p24

The ability of cyclophilin to bind a panel of recombinant HIV-gag proteins was assessed using sensitive, quantitative, sandwich enzyme-linked immunoso rbant assays (ELISAs). Significantly higher binding to cyclophilin was obse rved when recombinants contained at least 12 carboxy-terminal amino acids o f p17 in addition to p24 sequences. These results indicate that the carboxy -terminus of p17 is important for optimal binding of cyclophilin to p24 and support the theory that cyclophilin acts on the uncleaved HIV-1 gag (p17-p 24) precursor.