The Mechanism of Action of Hepatitis B Virus Capsid Assembly Modulators Can Be Predicted from Binding to Early Assembly Intermediates

Interfering with the self-assembly of virus nucleo-capsids is a promising approach for the development of novelantiviral agents. Applied to hepatitis B virus (HBV), this approach has led to several classes of capsid assembly modulators (CAMs)that target the virus by either accelerating nucleocapsid assembly or misdirecting it into noncapsid-like particles, thereby inhibiting the HBV replication cycle. Here, we have assessed the structures of early nucleocapsid assembly intermediates, bound with and without CAMs, using molecular dynamics simulations. Wefindthat distinct conformations of the intermediates are induceddepending on whether the bound CAM accelerates or misdirectsassembly. Specifically, the assembly intermediates with boundmisdirecting CAMs appear to beflattened relative to those with bound accelerators. Finally, the potency of CAMs within the sameclass was studied. We find that an increased number of contacts with the capsid protein and favorable binding energies inferred from free energy perturbation calculations are indicative of increased potency