Human cytomegalovirus (CMV) susceptibility to currently approved antiviral drugs does not impact on CMV terminase complex polymorphism

Currently approved anti-human cytomegalovirus (CMV) drugs, all targeting the viral DNA polymerase, are associated with significant toxicities and emergence of drug resistance. In this context, CMV terminase complex constitutes a promising target for novel antiviral compounds. In this study, we describe the low natural polymorphism (interstrain identity >97.7% at both nucleotide and amino acid levels) of the terminase subunits pUL56 and pUL89, and the portal protein pUL104, among 63 CMV clinical strains, and we show that the CMV resistance profile to current DNA polymerase inhibitors has no impact on the natural polymorphism of CMV terminase complex. These results support the idea that both CMV clinical strains exhibiting either susceptibility or resistance to current CMV DNA polymerase inhibitors are comparably sensitive to novel inhibitors of CMV terminase complex, such as letermovir.