Unique region of the minor capsid protein of human parvovirus B19 is exposed on the virion surface.
Capsids of the B19 parvovirus are composed of major (VP2; 58 kD) and minor (VP1; 83 kD) structural proteins. These proteins are identical except for a unique 226 amino acid region at the amino terminus of VP1. Previous immunization studies with recombinant empty capsids have demonstrated that the presence of VP1 was required to elicit virus-neutralizing antibody activity. However, to date, neutralizing epitopes have been identified only on VP2. Crystallographic studies of a related parvovirus (canine parvovirus) suggested the unique amino-terminal portion of VP1 assumed an internal position within the viral capsid. To determine the position of VP1 in both empty capsids and virions, we expressed a fusion protein containing the unique region of VP1. Antisera raised to this protein recognized recombinant empty capsids containing VP1 and VP2, but not those containing VP2 alone, in an enzyme-linked immunosorbent assay. The antisera immunoprecipitated both recombinant empty capsids and human plasma-derived virions, and agglutinated the latter as shown by immune electron microscopy. The sera contained potent neutralizing activity for virus infectivity in vitro. These data indicate that a portion of the amino terminus of VP1 is located on the virion surface, and that this region contains intrinsic neutralizing determinants. The external location of the VP1-specific tail may provide a site for engineered heterologous epitope presentation in novel recombinant vaccines.
Rosenfeld
S J
SJ
Cell Biology Section, National Heart, Lung and Blood Institute, Bethesda, Maryland 20817.
Yoshimoto
K
K
Kajigaya
S
S
Anderson
S
S
Young
N S
NS
Field
A
A
Warrener
P
P
Bansal
G
G
Collett
M S
MS
D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D001483:Base Sequence; D002213:Capsid / Q000032:analysis* / Q000276:immunology; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D006801:Humans; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016732:Parvovirus B19, Human / Q000737:chemistry* / Q000276:immunology / Q000648:ultrastructure; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests
D000914:Antibodies, Viral; D000939:Epitopes; D009838:Oligodeoxyribonucleotides