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Journal of Virology, December 2006, p. 12017-12024, Vol. 80, No. 24
0022-538X/06/$08.00+0     doi:10.1128/JVI.01435-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Conformational Changes in the VP1-Unique Region of Native Human Parvovirus B19 Lead to Exposure of Internal Sequences That Play a Role in Virus Neutralization and Infectivity{triangledown}

Carlos Ros,1,2* Marco Gerber,1 and Christoph Kempf1,2

Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland,1 ZLB Behring AG, Wankdorfstrasse 10, 3000 Bern 22, Switzerland2

Received 7 July 2006/ Accepted 27 September 2006

The unique region of the capsid protein VP1 (VP1u) of human parvovirus B19 (B19) elicits a dominant immune response and has a phospholipase A2 (PLA2) activity, which is necessary for the infection. In contrast to the rest of the parvoviruses, the VP1u of B19 is thought to occupy an external position in the virion, making this region a promising candidate for vaccine development. By using a monoclonal antibody against the most-N-terminal portion of VP1u, we revealed that this region rich in neutralizing epitopes is not accessible in native capsids. However, exposure of capsids to increasing temperatures or low pH led to its progressive accessibility without particle disassembly. Although unable to bind free virus or to block virus attachment to the cell, the anti-VP1u antibody was neutralizing, suggesting that the exposure of the epitope and the subsequent virus neutralization occur only after receptor attachment. The measurement of the VP1u-associated PLA2 activity of B19 capsids revealed that this region is also internal but becomes exposed in heat- and in low-pH-treated particles. In sharp contrast to native virions, the VP1u of baculovirus-derived B19 capsids was readily accessible in the absence of any treatment. These results indicate that stretches of VP1u of native B19 capsids harboring neutralizing epitopes and essential functional motifs are not external to the capsid. However, a conformational change renders these regions accessible and triggers the PLA2 potential of the virus. The results also emphasize major differences in the VP1u conformation between natural and recombinant particles.

* Corresponding author. Mailing address: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland. Phone: 41 31 6314349. Fax: 41 31 6314887. E-mail: carlos.ros{at}ibc.unibe.ch.

{triangledown} Published ahead of print on 4 October 2006.

Journal of Virology, December 2006, p. 12017-12024, Vol. 80, No. 24
0022-538X/06/$08.00+0     doi:10.1128/JVI.01435-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Bonsch, C., Kempf, C., Ros, C. (2008). Interaction of Parvovirus B19 with Human Erythrocytes Alters Virus Structure and Cell Membrane Integrity. J. Virol. 82: 11784-11791 [Abstract] [Full Text]  
  • Kaufmann, B., Chipman, P. R., Kostyuchenko, V. A., Modrow, S., Rossmann, M. G. (2008). Visualization of the Externalized VP2 N Termini of Infectious Human Parvovirus B19. J. Virol. 82: 7306-7312 [Abstract] [Full Text]  
  • Day, P. M., Gambhira, R., Roden, R. B. S., Lowy, D. R., Schiller, J. T. (2008). Mechanisms of Human Papillomavirus Type 16 Neutralization by L2 Cross-Neutralizing and L1 Type-Specific Antibodies. J. Virol. 82: 4638-4646 [Abstract] [Full Text]  


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