Human T-cell leukemia virus (HTLV-1) infects about 15-20 million individuals worldwide and is the etiological agentofanadultT-cellleukemia/lymphoma(ATLL),andcanalsoresultinaninflammatorydiseasesyndrome calledHTLV-1-associatedmyelopathy(HAM)/tropicalspasticparaparesis(TSP).HTLV-1antibodyprevalence rates vary among geographical areas, ranging from 0.2 to 10% among adults. This antibody prevalence increaseswithage,andcanaffectasmuchas20to50%ofthefemalepopulationaged60andabove.HTLV-1 is notorious for being difficult to study in cell culture, which has prohibited a rigorous analysis of how these viruses replicate in cells, including the steps involved in retrovirus assembly. The details for how retrovirus particle assembly occurs are poorly understood even for other more tractable retroviral systems like that of human immunodeficiency virus type 1 (HIV-1). For instance, recent evidence indicates that Gag-Gag interactionsdifferamongretroviruses,whichhelpsexplainmorphologicaldifferencesthatwehavedocumented amongimmatureretrovirusparticles.Furthermore,theroleformembrane-bound,non-punctate(np)Gaginthe biogenesisofGagpuncta,aswellasthenatureofGagpunctabiogenesisinthecontextofcell-to-cellcontacts alsoremainpoorlyunderstoodaspectsoftheretrovirusassemblypathway.ThisisparticularlyforHTLV-1,for which we have found to have fundamentally distinct differences to that of HIV-1 regarding the role of membrane-bound np Gag in Gag punta biogenesis. In this application, we propose to continue our investigations on HTLV-1 immature and mature particle structure and particle biogenesis through innovative state-of-the-artexperimentalapproacheswithappropriatecomparativeanalyseswithHIV-1.Inparticular,we willapplycryo-electronmicroscopy/tomography(cryo-EM/ET),photoactivatedlocalizationmicroscopy(PALM), total internal reflection fluorescence (TIRF) microscopy and the novel technology of z-scan fluorescence fluctuation spectroscopy (FFS) in living cells to investigate 1) analysis of immature HTLV-1 Gag lattice structure, 2) the importance of membrane-bound, np Gag in HTLV-1 particle biogenesis, and 3) HTLV-1 particle biogenesis in the context of cell-cell contacts. Careful comparisons will be done with HIV-1. These novel studies harness innovative technologies in order to provide new insights into a highly significant and poorlyunderstoodaspectoftheHTLV-1particleassemblyprocess,whichisfundamentallydistinctfromthatof HIV-1andotherretroviruses.Furthermore,ourstudiesrepresentsomeofthemostdetailedstudiesconducted ontheassemblyofvirusstructuralproteins,whichprovidesfundamentallyimportantinformationinvirologyon themolecularnatureofvirusparticleassemblyattheplasmamembraneforenvelopedviruses.

Public Health Relevance

Human T-cell leukemia virus type 1 (HTLV-1) is a cancer-causing human retrovirus that infects about 15-20 millionindividualsworldwide.HTLV-1antibodyprevalenceratesvaryamonggeographicalareas,rangingfrom 0.2to10%amongadults.Thisantibodyprevalenceincreaseswithage,andcanaffectasmuchas20to50% of the female population aged 60 and above.Fundamental studies of HTLV-1 assembly will lead to detailed informationabouttheprocessesunderlyingHTLV-1assemblyandemphasizethedistinctdifferencesthatexist with that of human immunodeficiency virus type 1 (HIV-1). This information will be useful for a better understanding of the distinct nature of HTLV-1 replication in cells, which may inform new therapeutic strategies.Furthermore,thesestudieswillprovidesomeofthemostdetailedinformationregardingthegeneral natureofvirusstructuralproteinassemblytoproducevirusparticles,particularlythatofenvelopedvirusesthat assembleattheplasmamembrane.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM098550-07
Application #
9689318
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Sakalian, Michael
Project Start
2012-09-28
Project End
2021-04-30
Budget Start
2019-05-01
Budget End
2020-04-30
Support Year
7
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Dentistry
Type
Schools of Dentistry/Oral Hygn
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
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Martin, Jessica L; Maldonado, José O; Mueller, Joachim D et al. (2016) Molecular Studies of HTLV-1 Replication: An Update. Viruses 8:

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