Role of heat-shock protein 90 in hepatitis E virus capsid trafficking

Abstract

p239 is a virus-like particle constituted from hepatitis E virus (HEV) recombinant proteins. It can be used as a surrogate for HEV and as an investigative tool to study cellular interactions because of its ability to adsorb to and penetrate HepG2 cellular membranes. Our objective was to use p239 to define the role of HEV capsid proteins during the early stages of infection. Pull-down and MALDI-TOF MS experiments identified three host-cell proteins, Grp 78/Bip, a-tubulin and heatshock protein 90 (HSP90), and the latter was investigated further. Antibodies to p239 alone or HSP90 alone could detect p239 or HSP90, suggesting the formation of a complex between p239 and HSP90. In the HepG2 cell, geldanamycin (GA), an HSP90-specific inhibitor, blocked intracellular transportation of p239, but had no effect on the binding and cellular entry of p239, suggesting that HSP90 was important for HEV capsid intracellular transportation. RT-PCR results showed that the efficiency of wild-type HEV infection was inhibited significantly by GA treatment, suggesting the importance of HSP90 in virus infectivity. It was concluded that HSP90 plays a crucial role in the intracellular transportation of viral capsids in the early stage of HEV infection.

Review article: hepatitis E—a concise review of virology, epidemiology, clinical presentation and therapy

“…28 Negative sense intermediate replicates are detected during replication and attachment receptors have been identified but overall, the viral life cycle of HEV has not been extensively studied. 29,30 This is, in part, due to the slow progress in the development of reliable culture methods for HEV. Similarly, in vivo studies have been hampered due to the absence of a small animal model, until recently;…”

Proteomics for development of vaccine

“…The viral core protein 4a associates with Hsp90-containing complexes in the infected cells, but no Hsp90 was detected in purified IMV vaccinia particles [98]. The Hsp90 plays a crucial role in the intracellular transportation of viral capsids in the early stage of hepatitis E virus infection as measured by pull-down and MALDI-TOF MS experiments [99]. The importance of Hsp90 for the replication of multiple viruses opens up an interesting possibility for developing new general antiviral strategies [100].…”

Therapeutic targets for the treatment of hepatitis E virus infection

“…A number of host cellular proteins have been demonstrated to interact with capsid. Heat shock protein (HSP) 90 may serve as an attachment receptor facilitating HEV entry into host cells 59 . Additionally, glucose-regulated protein (GRP) 78 and heparin sulfate proteoglycans (HSPGs) bind to capsid and are thought to be involved in intracellular transport 60, 61 .…”