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Structure of Parvovirus B19 Decorated by Fabs from a Human Antibody
Yingyuan Sun1, Thomas Klose1, Yue Liu1
1Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA.
Abstract:
Parvovirus B19, one of the most common human pathogens, is a small DNA virus that belongs to the Parvoviridae As a result of previous infections, antibodies to B19 are present in most adults. B19 has a strong tropism to erythroid progenitor cells and is able to cause a series of medical conditions, including fifth disease, arthritis, myocarditis, hydrops fetalis, and aplastic crisis. No approved vaccine is currently available for B19, and there is a lack of structural characterization of any B19 epitopes. Here we present the first cryo-electron microscopy (cryo-EM) structure of a B19 virus-like particle (VLP) complexed with the antigen-binding fragment (Fab) of a human neutralizing antibody, 860-55D. A model was built into the 3.2-Å-resolution map, and the antigenic residues on the surface of the B19 capsid were identified. Antibody 860-55D bridges the capsid of B19 by binding to a quaternary structure epitope formed by residues from three neighboring VP2 capsid proteins.IMPORTANCE Parvovirus B19 is a common human pathogen and a particular threat to children, pregnant women, and patients with sickle cell disease or AIDS. Currently, neutralizing antibody is the most efficient treatment for acute B19 infections. Research on the antigenic properties of B19 will guide the usage of these antibodies and facilitate vaccine development. We have determined and report here the high-resolution structure of B19 virus-like particles (VLPs) complexed with the Fab of a human neutralizing antibody. The structure shows a quaternary structure epitope formed by three VP2 proteins and provides details on host recognition of human B19 virus.
Insights
The first structure of a human Parvovirus B19 (B19) virus-like particle complexed with a neutralizing antibody reveals a quaternary epitope. This finding is crucial for developing effective B19 vaccines and antibody therapies.
Area of Science:
- Virology
- Structural Biology
- Immunology
Background:
- Parvovirus B19 is a common human pathogen causing various medical conditions.
- Antibodies against B19 are prevalent in adults, but no vaccine is approved.
- Structural characterization of B19 epitopes is lacking, hindering therapeutic development.
Purpose of the Study:
- To determine the high-resolution structure of B19 virus-like particles (VLPs) complexed with a neutralizing antibody.
- To identify antigenic residues and characterize the epitope recognized by the antibody.
- To provide insights for B19 vaccine development and antibody-based treatments.
Main Methods:
- Cryo-electron microscopy (cryo-EM) was used to determine the structure of B19 VLPs bound to the Fab fragment of antibody 860-55D.
- A 3.2-Å resolution map was generated, and a molecular model was built.
- The interaction interface between the antibody and the viral capsid was analyzed.
Main Results:
- The first cryo-EM structure of a B19 VLP-antibody complex was determined.
- A quaternary structure epitope, formed by residues from three neighboring VP2 capsid proteins, was identified.
- The structure reveals how antibody 860-55D binds and neutralizes B19, bridging capsid proteins.
Conclusions:
- The determined structure provides critical information on B19 antigenic properties.
- Understanding the quaternary epitope is essential for guiding the development of B19 vaccines.
- This research facilitates the design of more effective neutralizing antibodies for treating B19 infections.
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