Abstract
ABSTRACTProductive picornavirus infection requires the hijacking of host cell pathways to aid with the different stages of virus entry, synthesis of the viral polyprotein, and viral genome replication. Many picornaviruses, including foot-and-mouth disease virus (FMDV), assemble capsids via the multimerization of several copies of a single capsid precursor protein into a pentameric subunit which further encapsidates the RNA. Pentamer formation is preceded by co- and posttranslational modification of the capsid precursor (P1-2A) by viral and cellular enzymes and the subsequent rearrangement of P1-2A into a structure amenable to pentamer formation. We have developed a cell-free system to study FMDV pentamer assembly using recombinantly expressed FMDV capsid precursor and 3C protease. Using this assay, we have shown that two structurally different inhibitors of the cellular chaperone heat shock protein 90 (hsp90) impeded FMDV capsid precursor processing and subsequent pentamer formation. Treatment of FMDV permissive cells with the hsp90 inhibitor prior to infection reduced the endpoint titer by more than 10-fold while not affecting the activity of a subgenomic replicon, indicating that translation and replication of viral RNA were unaffected by the drug.IMPORTANCE FMDV of the Picornaviridae family is a pathogen of huge economic importance to the livestock industry due to its effect on the restriction of livestock movement and necessary control measures required following an outbreak. The study of FMDV capsid assembly, and picornavirus capsid assembly more generally, has tended to be focused upon the formation of capsids from pentameric intermediates or the immediate cotranslational modification of the capsid precursor protein. Here, we describe a system to analyze the early stages of FMDV pentameric capsid intermediate assembly and demonstrate a novel requirement for the cellular chaperone hsp90 in the formation of these pentameric intermediates. We show the added complexity involved for this process to occur, which could be the basis for a novel antiviral control mechanism for FMDV.
Highlights
Productive picornavirus infection requires the hijacking of host cell pathways to aid with the different stages of virus entry, synthesis of the viral polyprotein, and viral genome replication
We have investigated the requirements for foot-andmouth disease virus (FMDV) assembly and provide evidence of a role for the cellular chaperone hsp90 in the processing of the capsid precursor, which is a vital step required for precursor multimerization into pentameric subunits and capsid assembly
Pharmacological inhibition of hsp90 resulted in dosedependent reduced viral growth in cell culture without affecting translation or replication of a subgenomic reporter replicon. hsp90 inhibition was shown to reduce P1-2A processing and pentamer formation in a cell-free system, demonstrating that FMDV assembly requires the cellular chaperone machinery
Summary
Productive picornavirus infection requires the hijacking of host cell pathways to aid with the different stages of virus entry, synthesis of the viral polyprotein, and viral genome replication. Many picornaviruses, including foot-andmouth disease virus (FMDV), assemble capsids via the multimerization of several copies of a single capsid precursor protein into a pentameric subunit which further encapsidates the RNA. We have developed a cell-free system to study FMDV pentamer assembly using recombinantly expressed FMDV capsid precursor and 3C protease Using this assay, we have shown that two structurally different inhibitors of the cellular chaperone heat shock protein 90 (hsp90) impeded FMDV capsid precursor processing and subsequent pentamer formation. In FMDV, cotranslational processing results in the generation of a capsid precursor, P1-2A (FMDV genome structure [Fig. 1A]) This capsid precursor is proteolytically processed by a virally encoded protease, 3C viral protease (3Cpro), to form cleavage products VP0, VP1, and VP3, which remain associated as the protomer, the basic subunit of capsid assembly [4]. Recombinant empty capsids can be generated through the expression of the capsid precursor along with 3C protease in heterologous systems [11,12,13,14]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
