Inhibition assays demonstrated that the LRTV-1 peptide inhibited the infection of X4 (IIIB) and R5 (BaL) viruses in MT-4 and MT4-CCR5 cells with IC50 values of 45 ± 1.6 and 58 ± 1.8 μmol/L, respectively. This evidence concerns the gene CCR5 and infection.