Retrovirus Entry and Virus Evolution

Project: Research project

Project Details


Retroviruses, which include many important pathogens of humans and animals, have become important research
tools as benign gene delivery vectors, and have potential as therapeutic vectors for gene therapy. Whether pathogenic
or therapeutic, the initial infection and subsequent dissemination of the virus depends on efficient entry of the retrovirus
into host cells. While a detailed understanding of the mechanisms of viral entry has not been clearly defined for any
retrovirus, all retroviruses share a common overall strategy for entry into cells. The initial step of retrovirus entry, the
interaction between the viral surface glycoprotein (SU) and a cellular receptor, is complex, involving multiple,
noncontiguous determinants in both proteins that specify receptor choice, binding affinity and the ability to trigger
conformational changes in the viral glycoproteins. Despite the complexity of this interaction, retroviruses have the
ability to evolve the structure of their envelope glycoproteins to use a different cellular protein as a receptor, often a
protein that has no obvious homology to the original receptor, and retain efficient entry functions. How do retroviruses
do this? Understanding this ability will provide valuable information for antiviral intervention and targeting gene
We hypothesize that: (1) the envelope glycoproteins are organized into functional domains that allow changes to
occur in receptor choice by mutation and/or recombination while maintaining a critical level of both receptor binding
affinity and the ability to trigger glycoprotein conformational changes to initiate the fusion process; (2) multiple,
noncontiguous receptor interaction determinants located in the SU hypervariable domains are required for binding
affinity and to restrict or broaden receptor usage; (3) regions outside of the SU hypervariable domains will function to
connect receptor binding to triggering the glycoprotein lock mechanism and will be conserved as the virus changes
receptor usage. The homologous group of retroviruses, the subgroups A through E (A-E) avian leukosis viruses (ALV),
provide a powerful model system to test these hypotheses by supplying highly related viruses that have evolved from a
common ancestor to utilize different receptors. Specifically, we aim to:
1. Genetically define functional regions/residues of the subgroup A-E ALV envelope glycoproteins important for
receptor binding affinity. 2. Genetically define functional regions/residues of the subgroup A-E ALV glycoproteins
important for the specificity of receptor usage. 3. Identify and characterize regions/residues in the ALV glycoproteins
important for connecting receptor binding to triggering the conformational changes that initiate the fusion process. 4.
Genetically define functional regions/residues of the ALV receptors necessary for binding affinity and triggering a
conformational change in the ALV glycoproteins. 5. Test soluble forms of the ALV glycoproteins for the ability to
produce crystals suitable for structural studies.
PERFORMANCESITE(S) (organization,city, state)
Mayo Clinic Rochester
Rochester, MN 55905
KEYPERSONNEL. See instructions. Use continuationpages as needed to provide the requiredinformationin the format shown below.
Start with Principal Investigator.List all other key personnelin alphabeticalorder, last namefirst.
Name Organization Role on Project
Mark J. Federspiel, Ph.D. Mayo Clinic Rochester Principal Investigator
Pranay D. Khare, Ph.D. Mayo Clinic Rochester Postdoctoral Fellow
Deborah C. Melder Mayo Clinic Rochester Senior Technician
Disclosure Permission Statement. Applicableto SBIR/STTROnly. See instructions. [] Yes [] No
_PHS 398 (Rev. 05/01) Page 2 Form Page2 _
Number pagesconsecutivelyat the bottom throughoutthe application.Do no_u_sttesuffixessuch as 3a, 3b.
_ Principal Investigator/Program Director (Last, first, middle): Federspiel, Mark J.
The name of the principal investigator/program director must be provided at the top of each printed page and each continuation page.
Page Numbers
Face Page ......................................................................................................................................................... 1
StatusNot started


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