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Journal of Virology, February 2006, p. 1563-1573, Vol. 80, No. 3
0022-538X/06/$08.00+0 doi:10.1128/JVI.80.3.1563-1573.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
Mari-Paz Rubio,1,
,
Nathan Bryant,2
Robert McKenna,2
Mavis Agbandje-McKenna,2 and
José M. Almendral1*
Centro de Biología Molecular "Severo Ochoa" (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), 28049 Cantoblanco, Madrid, Spain,1 Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 326102
Received 24 August 2005/ Accepted 10 November 2005
The role of receptor recognition in the emergence of virulent viruses was investigated in the infection of severe combined immunodeficient (SCID) mice by the apathogenic prototype strain of the parvovirus minute virus of mice (MVMp). Genetic analysis of isolated MVMp viral clones (n = 48) emerging in mice, including lethal variants, showed only one of three single changes (V325M, I362S, or K368R) in the common sequence of the two capsid proteins. As was found for the parental isolates, the constructed recombinant viruses harboring the I362S or the K368R single substitutions in the capsid sequence, or mutations at both sites, showed a large-plaque phenotype and lower avidity than the wild type for cells in the cytotoxic interaction with two permissive fibroblast cell lines in vitro and caused a lethal disease in SCID mice when inoculated by the natural oronasal route. Significantly, the productive adsorption of MVMp variants carrying any of the three mutations selected through parallel evolution in mice showed higher sensitivity to the treatment of cells by neuraminidase than that of the wild type, indicating a lower affinity of the viral particle for the sialic acid component of the receptor. Consistent with this, the X-ray crystal structure of the MVMp capsids soaked with sialic acid (N-acetyl neuraminic acid) showed the sugar allocated in the depression at the twofold axis of symmetry (termed the dimple), immediately adjacent to residues I362 and K368, which are located on the wall of the dimple, and approximately 22 Å away from V325 in a threefold-related monomer. This is the first reported crystal structure identifying an infectious receptor attachment site on a parvovirus capsid. We conclude that the affinity of the interactions of sialic-acid-containing receptors with residues at or surrounding the dimple can evolutionarily regulate parvovirus pathogenicity and adaptation to new hosts.
Present address: Centro de Investigación Principe Felipe, 46013 Valencia, Spain.
A.L.-B. and M.-P.R. contributed equally to this work.
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