3D visualization of HIV transfer at the virological synapse between dendritic cells and T cells

3D visualization of HIV transfer at the virological synapse between dendritic cells and T cells
Richard L. Feltsa,1, Kedar Narayana,1, Jacob D. Estesb, Dan Shia, Charles M. Trubeyb, Jing Fua, Lisa M. Hartnella, Gordon T. Ruthelc, Douglas K. Schneiderb, Kunio Nagashimad, Julian W. Bess Jr.b, Sina Bavaric, Bradley C. Lowekampe, Donald Blisse, Jeffrey D. Lifsonb, and Sriram Subramaniama,2
+ Author Affiliations

aLaboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892;
bAIDS and Cancer Virus Program and
dElectron Microscopy Laboratory, SAIC-Frederick, Inc., National Cancer Institute, Frederick, MD 21702;
cUS Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702; and
eNational Library of Medicine, National Institutes of Health, Bethesda, MD 20892
Edited* by Bernard Moss, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, and approved June 14, 2010 (received for review March 10, 2010)

↵1R.L.F. and K.N. contributed equally to this work.

Abstract
The efficiency of HIV infection is greatly enhanced when the virus is delivered at conjugates between CD4+ T cells and virus-bearing antigen-presenting cells such as macrophages or dendritic cells via specialized structures known as virological synapses. Using ion abrasion SEM, electron tomography, and superresolution light microscopy, we have analyzed the spatial architecture of cell-cell contacts and distribution of HIV virions at virological synapses formed between mature dendritic cells and T cells. We demonstrate the striking envelopment of T cells by sheet-like membrane extensions derived from mature dendritic cells, resulting in a shielded region for formation of virological synapses. Within the synapse, filopodial extensions emanating from CD4+ T cells make contact with HIV virions sequestered deep within a 3D network of surface-accessible compartments in the dendritic cell. Viruses are detected at the membrane surfaces of both dendritic cells and T cells, but virions are not released passively at the synapse; instead, virus transfer requires the engagement of T-cell CD4 receptors. The relative seclusion of T cells from the extracellular milieu, the burial of the site of HIV transfer, and the receptor-dependent initiation of virion transfer by T cells highlight unique aspects of cell-cell HIV transmission.

3D imaging cell–cell contact electron tomography viral entry neutralizing antibodies
Footnotes
2To whom correspondence should be addressed. E-mail: ss1@nih.gov. Author contributions: R.L.F., K. Narayan, J.D.E., J.D.L., and S.S. designed research; R.L.F., K. Narayan, J.D.E., D.S., C.M.T., J.F., L.M.H., G.T.R., D.K.S., and K. Nagashima performed research; J.W.B., Jr., S.B., J.D.L., and S.S. contributed new reagents/analytic tools; R.L.F., K. Narayan, B.C.L., D.B., J.D.L., and S.S. analyzed data; and S.S. wrote the paper.
The authors declare no conflict of interest.
↵*This Direct Submission article had a prearranged editor.
This article contains supporting information online at
www.pnas.org/lookup/suppl/doi:10.1073/pnas.1003040107/-/DCSupplemental.

http://www.pnas.org/content/107/30/13336