Retroviruses are enveloped viruses that form by pinching off from cellular membranes. Upon maturation, released particles are competent to infect receptor-expressing cells. During entry, virus and cell membranes fuse and capsids disassemble in the cytoplasm. Virus budding and virus entry are commonly studied as separate processes. In reality, they are coordinated as most viruses spread when cells contact each other, rather than relying on diffusion to reach target cells. Under conditions of cell-cell contact, virus spreading is 2-3 orders of magnitude more efficient. To understand why this is the case, we use the murine leukemia virus (MLV) and the avain leukosis virus (ALV) as model systems. Chronically infected cells producing fluorescently labeled virions are co-cultured with target cells expressing fluorescent receptor. Using this system, we have visualized cell-to-cell transmission of retroviruses in living cells. Our results reveal a novel mode of viral spreading via thin cellular bridges that are formed from actin-rich filopodia. These bridges originate from non-infected cells and are anchored to the infected cells. Viruses form and bud preferentially at the site of filopodial anchorage and move along the outer surface of filopodial bridges, surfing, toward neighboring cells to infect them. Thus, our time-lapse movies offer a strong visual explanation for the efficient viral spreading under conditions of cell-cell contact. This system provides an excellent tool to dissect the molecular mechanism of cell-to-cell transmission and a number of questions can now be addressed. How are filopodial bridges formed? Is virus assembly directed towards sites of cell-cell contact? And how does virus binding to target cell filopodia engage the underlying retrograde F-actin flow to move towards the target cells? The underlying molecular principles determined in this proposal will likely apply to other modes of cell-to-cell transmission and offer insights into the ability of cells to communicate with each other. This research proposal will lead to a better understanding as to why oncogenic retroviruses spread efficiently from cell to cell. Newly identified cellular factors involved in this process could serve as potential new targets for antiviral and anti-cancer strategies.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA098727-10
Application #
8211076
Study Section
Virology - B Study Section (VIRB)
Program Officer
Read-Connole, Elizabeth Lee
Project Start
2003-03-12
Project End
2013-01-31
Budget Start
2012-02-01
Budget End
2013-01-31
Support Year
10
Fiscal Year
2012
Total Cost
$279,073
Indirect Cost
$110,449
Name
Yale University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Riedel, Christiane; Vasishtan, Daven; Siebert, C Alistair et al. (2016) Native structure of a retroviral envelope protein and its conformational change upon interaction with the target cell. J Struct Biol :
Kong, Rui; Xu, Kai; Zhou, Tongqing et al. (2016) Fusion peptide of HIV-1 as a site of vulnerability to neutralizing antibody. Science 352:828-33
Sewald, Xaver; Motamedi, Nasim; Mothes, Walther (2016) Viruses exploit the tissue physiology of the host to spread in vivo. Curr Opin Cell Biol 41:81-90
Agosto, Luis M; Uchil, Pradeep D; Mothes, Walther (2015) HIV cell-to-cell transmission: effects on pathogenesis and antiretroviral therapy. Trends Microbiol 23:289-95
Sewald, Xaver; Ladinsky, Mark S; Uchil, Pradeep D et al. (2015) Retroviruses use CD169-mediated trans-infection of permissive lymphocytes to establish infection. Science 350:563-7
Uchil, Pradeep D; Pawliczek, Tobias; Reynolds, Tracy D et al. (2014) TRIM15 is a focal adhesion protein that regulates focal adhesion disassembly. J Cell Sci 127:3928-42
Li, Fei; Sewald, Xaver; Jin, Jing et al. (2014) Murine leukemia virus Gag localizes to the uropod of migrating primary lymphocytes. J Virol 88:10541-55
Zhong, Peng; Agosto, Luis M; Munro, James B et al. (2013) Cell-to-cell transmission of viruses. Curr Opin Virol 3:44-50
Huang, Fang; Hartwich, Tobias M P; Rivera-Molina, Felix E et al. (2013) Video-rate nanoscopy using sCMOS camera-specific single-molecule localization algorithms. Nat Methods 10:653-8
Li, Fei; Jin, Jing; Herrmann, Christin et al. (2013) Basic residues in the matrix domain and multimerization target murine leukemia virus Gag to the virological synapse. J Virol 87:7113-26

Showing the most recent 10 out of 26 publications