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Open Access Short report

Secretory pathway antagonism by calicivirus homologues of Norwalk virus nonstructural protein p22 is restricted to noroviruses

Tyler M Sharp13, Sue E Crawford1, Nadim J Ajami1, Frederick H Neill1, Robert L Atmar1, Kazuhiko Katayama2, Budi Utama1 and Mary K Estes1*

Author Affiliations

1 Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, 77030, USA

2 Virology II, National Institute of Infectious Diseases, Musashi-murayama, Tokyo, Japan

3 Present address: Dengue Branch, Centers for Disease Control and Prevention, San Juan, PR, USA

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Virology Journal 2012, 9:181  doi:10.1186/1743-422X-9-181

Published: 3 September 2012

Abstract

Background

Our previous report that the Norwalk virus nonstructural protein p22 is an antagonist of the cellular secretory pathway suggests a new aspect of norovirus/host interaction. To explore conservation of function of this highly divergent calicivirus protein, we examined the effects of p22 homologues from four human and two murine noroviruses, and feline calicivirus on the secretory pathway.

Findings

All human noroviruses examined induced Golgi disruption and inhibited protein secretion, with the genogroup II.4 Houston virus being the most potent antagonist. Genogroup II.6 viruses have a conserved mutation in the mimic of an Endoplasmic Reticulum export signal (MERES) motif that is highly conserved in human norovirus homologues of p22 and is critical for secretory pathway antagonism, and these viruses had reduced levels of Golgi disruption and inhibition of protein secretion. p22 homologues from both persistent and nonpersistent strains of murine norovirus induced Golgi disruption, but only mildly inhibited cellular protein secretion. Feline calicivirus p30 did not induce Golgi disruption or inhibit cellular protein secretion.

Conclusions

These differences confirm a norovirus-specific effect on host cell secretory pathway antagonism by homologues of p22, which may affect viral replication and/or cellular pathogenesis.

Keywords:
Calicivirus; Norovirus; p22; Secretory pathway