Cell infection by animal viruses is controlled by their structural proteins and by variation in those structures. Viral proteins interact with host cell receptors, leading to binding, uptake and intracellular trafficking, while interactions with host antibodies may neutralize infection with varying efficiencies. Many functions of viral structural proteins are still not fully understood, including the structural effects of receptor or antibody binding in controlling infection. Here we will continue to investigate those processes using parvovirus capsids as a model. The viruses being studied include canine parvovirus (CPV), which arose as a new pandemic pathogen due to changes in its interaction with the host transferrin receptor type-1 (TfR). The parvovirus capsids also bind antibodies to several epitopes with significant variation in the resulting neutralization. In the previous period we have generated important new information about the structures and functions of capsids, the roles of TfR variants in infection, and the binding of antibodies. The tools developed allow us to manipulate each component in order to understand how they control virus infection. The studies are presented as three complementary Aims:
Aim 1. Explain the structural role of the receptor in the infectious process, and the effects of host- specific structural variation. Define the interactions of TfR apical domain mutants and variants with the complementary viral capsid structures, and explain how those control cell infection and viral host tropisms. Show how the receptor binding alters the capsid to prepare it for infection. Use other ligands to bind the capsid to result in endocytosis, and investigate the effects on infection.
Aim 2. Define the capsid-mediated processes and structural variation required for cell infection. We have identified single changes in different capsid structures that prevent infection, and some of those appear to control key variation required for successful cell infection. We will define how those structures control the capsid functions, in particular the sources of specific intra-capsid cleavages. We will determine the high resolution structures of capsids with altered infectious properties using cryo-EM approaches. Those sites are asymmetric, as they occur in only ~10% of the capsid proteins. We will therefore use a variety of structural and biochemical approaches to study those structures and to explain their functions in the processes of cell infection.
Aim 3. Analyze the interactions of antibodies with the capsid to explain the mechanisms of binding, neutralization, and antibody escape. Use high-resolution structures of capsid-Fab complexes to explain antibody-binding specificity, and also to understand how those interactions result in neutralization in some cases but not others. Use antibody and capsid mutations to alter the binding, neutralization, and cross- reactivity of antibodies, to define the functional interactions between capsids, antibodies, and receptors.

Public Health Relevance

Viral proteins and capsids control the process of infection, determine which hosts are susceptible, and also mediate specific interactions with host proteins such as receptors and antibodies. The various functions of all viruses are therefore controlled by the structures of the proteins, by the ways in which they vary under different conditions, or by their interactions with each other and with host proteins. Here we will continue to determine how the parvovirus capsid mediates host-specific cell infection, and how the viral infection and cell-cell spread are controlled by the structures of the cell receptors and by the binding of anti-viral antibodies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI092571-08
Application #
9679451
Study Section
Virology - A Study Section (VIRA)
Program Officer
Natarajan, Ramya
Project Start
2010-12-01
Project End
2022-04-30
Budget Start
2019-05-01
Budget End
2020-04-30
Support Year
8
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Cornell University
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
872612445
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Callaway, Heather M; Welsch, Kathrin; Weichert, Wendy et al. (2018) Complex and dynamic interactions between parvovirus capsids, transferrin receptors and antibodies control cell infection and host range. J Virol :
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Organtini, Lindsey J; Lee, Hyunwook; Iketani, Sho et al. (2016) Near-Atomic Resolution Structure of a Highly Neutralizing Fab Bound to Canine Parvovirus. J Virol 90:9733-9742
Allison, Andrew B; Organtini, Lindsey J; Zhang, Sheng et al. (2016) Single Mutations in the VP2 300 Loop Region of the Three-Fold Spike of the Carnivore Parvovirus Capsid Can Determine Host Range. J Virol 90:753-67
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Löfling, Jonas; Lyi, Sangbom Michael; Parrish, Colin R et al. (2013) Canine and feline parvoviruses preferentially recognize the non-human cell surface sialic acid N-glycolylneuraminic acid. Virology 440:89-96
Stucker, Karla M; Pagan, Israel; Cifuente, Javier O et al. (2012) The role of evolutionary intermediates in the host adaptation of canine parvovirus. J Virol 86:1514-21

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