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Differential Utilization of CCR5 by Macrophage and T Cell Tropic Simian Immunodeficiency Virus Strains
Aimee L. Edinger, Angela Amedee, Karen Miller, Benjamin J. Doranz, Michael Endres, Matthew Sharron, Michel Samson, Zhao-Hai Lu, Janice E. Clements, Michael Murphey-Corb, Stephen C. Peiper, Marc Parmentier, Christopher C. Broder and Robert W. Doms
Proceedings of the National Academy of Sciences of the United States of America
Vol. 94, No. 8 (Apr. 15, 1997), pp. 4005-4010
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/41946
Page Count: 6
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Certain chemokine receptors serve as cofactors for HIV type 1 envelope (env)-mediated cell-cell fusion and virus infection of CD4-positive cells. Macrophage tropic (M-tropic) HIV-1 isolates use CCR5, and T cell tropic (T-tropic) strains use CXCR4. To investigate the cofactors used by simian immunodeficiency viruses (SIV), we tested four T-tropic and two M-tropic SIV env proteins for their ability to mediate cell-cell fusion with cells expressing CD4 and either human or nonhuman primate chemokine receptors. Unlike HIV-1, both M- and T-tropic SIV envs used CCR5 but not CXCR4 or the other chemokine receptors tested. However, by testing a panel of CCR5/CCR2b chimeras, we found that the structural requirements for CCR5 utilization by M-tropic and T-tropic SIV strains were different. T-tropic SIV strains required the second extracellular loop of CCR5 whereas a closely related M-tropic SIV strain could, like M-tropic HIV-1 strains, use the amino-terminal domain of CCR5. As few as two amino acid changes in the SIV env V3 domain affected the regions of CCR5 that were critical for fusogenic activity. Receptor signaling was not required for either fusion or infection. Our results suggest that viral tropism may be influenced not only by the coreceptors used by a given virus strain but also by how a given coreceptor is used.
Proceedings of the National Academy of Sciences of the United States of America © 1997 National Academy of Sciences