Heat shock protein-90-beta facilitates enterovirus 71 viral particles assembly

Molecular chaperones are reported to be crucial for virus propagation, but are not yet addressed in Human Enterovirus 71 (EV71). Here we describe the specific association of heat shock protein-90-beta (Hsp90 beta), but not alpha form (Hsp90 alpha), with EV71 viral particles by the co-purification with virions using sucrose density gradient ultracentrifugation, and by the colocalization with viral particles, as assessed by immunogold electron microscopy. The reduction of the Hsp90 beta protein using RNA interference decreased the correct assembly of viral particles, without affecting EV71 replication levels. Tracking ectopically expressed Hsp90 beta protein associated with EV71 virions revealed that Hsp90 beta protein was transmitted to new host cells through its direct association with infectious viral particles. Our findings suggest a new antiviral strategy in which extracellular Hsp90 beta protein is targeted to decrease the infectivity of EV71 and other enteroviruses, without affecting the broader functions of this constitutively expressed molecular chaperone. (C) 2013 Elsevier Inc. All rights reserved.