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Antiviral activities of papaverine and nucleoside analogs, 9-[(1,3-dihydroxy-2propoxy)methyl]guanine (DHPG) and acyclovir, against human cytomegalovirus (HCMV) infection were compared in ritro. Papaverine and DHPG were effective in reducing infectious
HCMV yields with ED5,s (effective dose 50: the concentraion at which 50% of virus yields
was obtained) of approximately 1.02 and 0.45 pM, respectively; while acyclovir was less effec
tive with an ED9, of about 10.4 pM. The relative cytotoxicity of these drugs was evaluated
under the same conditions used to measure infectious HCMV yields. Papaverine and DHPG demonstrated little cellular toxicity as measured by their effect on the viability of confluent cells at concentrations in the range of those demonstrating potent inhibition of HCMV replication. Similarly, protein synthesis was largely unaffected by these drugs in stationary mockinfected cells as measured by the incorporation of isotopically labelled amino acids. In contrast, cellular DNA synthesis was invariably reduced in the presence of either drug. HCMV-specific DNA synthesis was also strongly inhibited by papaverine and DHPG.
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