In vitro microtubule binding assays Puri®ed EEV particles were prepared as described previously (Ro Èttger et al., 1999) and subsequently were used to prepare virus cores following the method of Cudmore et al. (1996) . Rhodamine-labelled microtubules were prepared according to Hyman et al. (1991) . Vaccinia virus cores were incubated with rhodamine-labelled microtubules in BRB80 buffer containing 10 mM taxol for 5 min at room temperature. 4¢,6-diamidino-2phenylindole (DAPI) was added subsequently to a ®nal concentration of 0.1 mg/ml to label the virus cores. Finally, the mixture was diluted 1:1± 1:10 with antifade solution (0.1 mg/ml catalase, 0.1 mg/ml glucose oxidase, 10 mM glucose) and viewed without ®xation. Proteinase K or trypsin treatment of core particles prior to incubation with microtubules was performed as described previously (Roos et al., 1996) . Anti-A3L, A10L, L4R or control IgG antibodies were incubated with puri®ed cores for 1 h at room temperature prior to incubation with microtubules.