Identification of Factors Promoting HBV Capsid Self-Assembly by Assembly-Promoting Antivirals.

Around 270 million individuals currently live with hepatitis B virus (HBV) infection. Heteroaryldihydropyrimidines (HAPs) are a family of antivirals that target the HBV capsid protein and induce aberrant self-assembly. The capsids formed resemble the native capsid structure but are unable to propagate the virus progeny because of a lack of RNA/DNA. Under normal conditions, self-assembly is initiated by the viral genome. The mode of action of HAPs, however, remains largely unknown. In this work, using molecular dynamics simulations, we attempted to understand the action of HAP by comparing the dynamics of capsid proteins with and without HAPs. We found that the inhibitor is more stable in higher oligomers. It retains its stability in the hexamer throughout 1 μs of simulation. Our results also show that the inhibitor might help in stabilizing the C-terminus, the HBc 149-183 arginine-rich domain of the capsid protein. The C-termini of dimers interact with each other, assisted by the HAP inhibitor. During capsid assembly, the termini are supposed to directly interact with the viral genome, thereby suggesting that the viral genome might work in a similar way to stabilize the capsid protein. Our results may help in understanding the underlying molecular mechanism of HBV capsid self-assembly, which should be crucial for exploring new drug targets and structure-based drug design.