Fig. 2.

Ciclopirox inhibits in vitro and intracellular HBV capsid assembly. a Effects of ciclopirox, GLS-4, and Bay41–4109 on in vitro HBV capsid assembly. Various concentrations of ciclopirox, GLS-4, or Bay41–4109 were mixed with Cp149 in reaction buffer. After 1 h, the mixtures were subjected to a immunoblot analysis with anti-HBV core antibody. b Sucrose density gradient analysis of capsid assembly inhibition by ciclopirox. Ten fractions collected from top to bottom underwent immunoblot analysis. c, d Effect of ciclopirox on intracellular HBV capsid assembly. Huh-7 cells were transfected with (c) pCDNA3-Core or (d) pHBV1.2× and exposed after 12 h to the indicated concentrations of ciclopirox for 36 h. The cells were lysed and assembled HBV core particles were isolated by sucrose step gradient ultracentrifugation, resolved on 1% agarose gels, and subjected to immunoblot analysis with anti-HBV core antibody. e Electron micrographs of the effect of ciclopirox on in vitro HBV capsid assembly. The particles were negatively stained with 2% uranyl acetate. Scale bars = 200 nm and 100 nm. TEM magnifications, ×49,000 and ×75,000. Ciclopirox appeared to convert the T = 4 HBV capsid into T = 3 form (30 nm). The data shown in a–e are representative of three independent experiments and are expressed as mean ± SD. The error bars represent the ± SD. *p < 0.05; **p < 0.01, as determined by unpaired two-tailed Student’s t-tests. Source data are provided as a Source Data file