An orally bioavailable, non-nucleoside, 3,4-dihydroquinazolinyl acetic acid and inhibitor of the pUL56 subunit of the viral terminase complex of cytomegalovirus (CMV), with potential CMV-specific antiviral activity. Upon oral administration, letermovir binds to the pUL56 subunit of the viral terminase complex of CMV and prevents the cleavage of concatemeric DNA into monomeric genome length DNA. As this agent interferes with viral DNA processing and subsequent viral DNA packaging into procapsids, CMV replication is blocked and CMV infection is prevented.