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Title
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Structural analysis of a mutation in canine parvovirus which controls antigenicity and host range.
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Authors
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A.L.Llamas-Saiz,
M.Agbandje-McKenna,
J.S.Parker,
A.T.Wahid,
C.R.Parrish,
M.G.Rossmann.
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Ref.
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Virology, 1996,
225,
65-71.
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PubMed id
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Abstract
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A single mutation in canine parvovirus (CPV) of VP2 residue 300 from alanine to
aspartic acid causes a loss of canine host range and alters the antigenic
properties of the virus. The three-dimensional structure of this mutant has been
solved to 3.25 A resolution. Crystals of full particles were triclinic, with
cell dimensions of a = 267.6, b = 268.5, c = 274.3 A. alpha = 61.9, beta = 62.6,
and gamma = 60.2 degrees. The native structure of CPV was used as an initial
model. Phases were improved by real-space electron density averaging. In spite
of the relative low percentage of observed reflections (32.5% of the data
between 15.0 and 3.25 A resolution), the presence of 60-fold noncrystallographic
redundancy allowed the averaging procedure to converge smoothly. The mutant
aspartic acid at residue 300 forms a salt bridge with Arg81 in an icosahedrally
threefold-related subunit, inducing local changes within the antigenic site B on
the CPV surface. In addition, the loop between residues 359 and 374 adopts a
conformation similar to that displayed by feline panleukopenia virus. The
ability of the Ala300-->Asp mutant to evade antibody binding can be
associated with the change of charge distribution and structure in the antigenic
binding site. The variation in host range behavior may be due to the increased
stability as a result of formation of the salt bridge between adjacent subunits.
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