1. Human Tetherin Exerts Strong Selection Pressure on the HIV-1 Group N Vpu Protein.
- Author
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Sauter, Daniel, Unterweger, Daniel, Vogl, Michael, Usmani, Shariq M., Heigele, Anke, Kluge, Silvia F., Hermkes, Elisabeth, Moll, Markus, Barker, Edward, Peeters, Martine, Learn, Gerald H., Bibollet-Ruche, Frederic, Fritz, Joëlle V., Fackler, Oliver T., Hahn, Beatrice H., and Kirchhoff, Frank
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PROTEINS ,HIV infection transmission ,PANDEMICS ,LIGANDS (Biochemistry) ,KILLER cells - Abstract
HIV-1 groups M and N emerged within the last century following two independent cross-species transmissions of SIVcpz from chimpanzees to humans. In contrast to pandemic group M strains, HIV-1 group N viruses are exceedingly rare, with only about a dozen infections identified, all but one in individuals from Cameroon. Poor adaptation to the human host may be responsible for this limited spread of HIV-1 group N in the human population. Here, we analyzed the function of Vpu proteins from seven group N strains from Cameroon, the place where this zoonosis originally emerged. We found that these N-Vpus acquired four amino acid substitutions (E15A, V19A and IV25/26LL) in their transmembrane domain (TMD) that allow efficient interaction with human tetherin. However, despite these adaptive changes, most N-Vpus still antagonize human tetherin only poorly and fail to down-modulate CD4, the natural killer (NK) cell ligand NTB-A as well as the lipid-antigen presenting protein CD1d. These functional deficiencies were mapped to amino acid changes in the cytoplasmic domain that disrupt putative adaptor protein binding sites and an otherwise highly conserved ßTrCP-binding DSGxxS motif. As a consequence, N-Vpus exhibited aberrant intracellular localization and/or failed to recruit the ubiquitin-ligase complex to induce tetherin degradation. The only exception was the Vpu of a group N strain recently discovered in France, but originally acquired in Togo, which contained intact cytoplasmic motifs and counteracted tetherin as effectively as the Vpus of pandemic HIV-1 M strains. These results indicate that HIV-1 group N Vpu is under strong host-specific selection pressure and that the acquisition of effective tetherin antagonism may lead to the emergence of viral variants with increased transmission fitness. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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