Cytomegalovirus (CMV) is a betaherpesvirus with a 50 to 90% prevalence frequency in the adult human population. It is an opportunistic pathogen controlled largely by the immune system, especially cell-mediated immunity. Clinically serious disease occurs primarily in three situations involving deficient immune systems.
Treatment of HCMV disease is limited to relatively toxic drugs with that target viral DNA synthesis. The most commonly used HCMV drug, ganciclovir, is a nucleoside prodrug phosphorylated by the viral UL97 kinase to the nucleotide analog form and is selectively incorporated into progeny DNA by the HCMV UL54-encoded DNA polymerase. Foscarnet is a pyrophosphate analog. Effective concentrations of foscarnet are much higher than that of ganciclovir. Both of these drugs are nephrotoxic; ganciclovir also causes neutropenia and is teratogenic. Cidofovir is a nucleoside phosphonate that is severely renal toxic.