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Lack of Processing of the Expressed ORF1 Gene Product of Hepatitis E Virus

Suppiah, Suganthi
Zhou, Yumei
Frey, Teryl K.
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Abstract

Background: Proteolytic processing is a common mechanism among plus strand RNA viruses and the replicases of all plus strand RNA viruses of animals thus far characterized undergo such processing. The replicase proteins of hepatitis E virus (HEV) are encoded by ORF1. A previous report published by our group [1] provided data that processing potentially occurred when ORF1 (Burma strain; genotype 1) was expressed using a vaccinia virus-based expression system.

Findings: To further test for processing and to rule out artifacts associated with the expression system, ORF1 was re-expressed using a plasmid-based expression vector with the result that the previous processing profile could not be confirmed. When ORF1 from an HEV infectious cDNA clone (US swine strain; genotype 3) was expressed using the plasmid-based system, the only species detected was the 185 kDa precursor of ORF1. A putative papain-like cysteine protease [2] had been predicted within ORF1 using the original HEV genomic sequence. However, analysis of subsequent ORF1 sequences from a large number of HEV isolates reveals that this protease motif is not conserved.

Conclusions: The expressed HEV ORF1 gene product does not undergo proteolytic processing, indicating that the replicase precursor of HEV is potentially unique in this regard.

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Date
2011-01-01
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Research Projects
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Keywords
hepatitis E virus (HEV), ORF1, proteolytic processing, replicases, plus strand RNA viruses
Citation
Suppiah <em>et al.</em>: Lack of Processing of the Expressed ORF1 Gene Product of Hepatitis E Virus. <em>Virology Journal</em> 2011 8:245. doi: 10.1186/1743-422X-8-245
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