R)-9-(2-PHOSPHONYLMETHOXYPROPYL)-2,6-DIAMINOPURINE IS A POTENT INHIBITOR OF FELINE IMMUNODEFICIENCY VIRUS-INFECTION

The antiviral efficacy of acyclic nucleoside phosphonates, including 9 -(2-phosphonylmethoxyethyl)adenine (PMEA) and R)-9-(2-phosphonylmethox ypropyl)-2,6-diaminopurine [(R)-PMPDAP] against feline immunodeficienc y virus (FIV) infection was determined. (R)-PMPDAP showed the highest selectivity index (>2,000) in vitro. Treatment of experimentally FIV-i nfected asymptomatic cats with PMEA or (R)-PMPDAP had no effect on the CD4+/CD8+ ratio. However, mean plasma viral RNA concentrations decrea sed significantly in the (R)-PMPDAP-treated cats. Our data show that, in comparison to PMEA, (R)-PMPDAP is a more patent and less toxic inhi bitor of FIV replication both in vitro and in vivo.