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

- Hsp90β is associated with EV71 virion and is secreted with the release virus.
- Hsp90β effects on the correct assembly of viral particles.
- Viral titer of cultured medium was reduced in the presence of geldanamycin.
- Viral titer was also reduced when Hsp90β was suppressed by siRNA treatment.
- The extracellular Hsp90β was also observed in other RNA viruses-infected cells.

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 (Hsp90β), but not alpha form (Hsp90α), 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 Hsp90β protein using RNA interference decreased the correct assembly of viral particles, without affecting EV71 replication levels. Tracking ectopically expressed Hsp90β protein associated with EV71 virions revealed that Hsp90β 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 Hsp90β protein is targeted to decrease the infectivity of EV71 and other enteroviruses, without affecting the broader functions of this constitutively expressed molecular chaperone.