This Article Full Text Full Text (PDF) Other Versions of this Article: JVI.01847-07v1 82/2/817    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bonaparte, R. S. Articles by Krishna, N. K. Search for Related Content PubMed PubMed Citation Articles by Bonaparte, R. S. Articles by Krishna, N. K.

 Previous Article  |  Next Article 

Journal of Virology, January 2008, p. 817-827, Vol. 82, No. 2
0022-538X/08/$08.00+0     doi:10.1128/JVI.01847-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Human Astrovirus Coat Protein Inhibits Serum Complement Activation via C1, the First Component of the Classical Pathway

Rheba S. Bonaparte,¹ Pamela S. Hair,² Deepa Banthia,¹ Dawn M. Marshall,^1, Kenji M. Cunnion,^2,3 and Neel K. Krishna^1,2*

Departments of Microbiology and Molecular Cell Biology,¹ Pediatrics, Eastern Virginia Medical School,² Children's Specialty Group, Norfolk, Virginia 23507³

Received 22 August 2007/ Accepted 17 October 2007

Human astroviruses (HAstVs) belong to a family of nonenveloped, icosahedral RNA viruses that cause noninflammatory gastroenteritis, predominantly in infants. Eight HAstV serotypes have been identified, with a worldwide distribution. While the HAstVs represent a significant public health concern, very little is known about the pathogenesis of and host immune response to these viruses. Here we demonstrate that HAstV type 1 (HAstV-1) virions, specifically the viral coat protein (CP), suppress the complement system, a fundamental component of the innate immune response in vertebrates. HAstV-1 virions and purified CP both suppress hemolytic complement activity. Hemolytic assays utilizing sera depleted of individual complement factors as well as adding back purified factors demonstrated that HAstV CP suppresses classical pathway activation at the first component, C1. HAstV-1 CP bound the A chain of C1q and inhibited serum complement activation, resulting in decreased C4b, iC3b, and terminal C5b-9 formation. Inhibition of complement activation was also demonstrated for HAstV serotypes 2 to 4, suggesting that this phenomenon is a general feature of these human pathogens. Since complement is a major contributor to the initiation and amplification of inflammation, the observed CP-mediated inhibition of complement activity may contribute to the lack of inflammation associated with astrovirus-induced gastroenteritis. Although diverse mechanisms of inhibition of complement activation have been described for many enveloped animal viruses, this is the first report of a nonenveloped icosahedral virus CP inhibiting classical pathway activation at C1.

Published ahead of print on 24 October 2007.

Present address: The Scripps Research Institute, La Jolla, CA 92037.