The Vpu of an HIV-1 N strain from Togo is an effective tetherin antagonist.

<p>(<b>A</b>) Schematic representation of the origin of N1FR2011. This group N infection was diagnosed in Paris in a 57-year old male, 8 days after returning from Togo <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003093#ppat.1003093-Delaugerre1" target="_blank">[3]</a>. All other HIV-1 N infections were identified in individuals from Cameroon. (<b>B</b>) Evolutionary relationships among HIV-1 and SIVcpz Env amino acid sequences. Group N viruses are highlighted in blue; those containing an intact DSGxxS motif in their Vpu protein are labelled with an asterisk. The tree was inferred using maximum likelihood methods <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003093#ppat.1003093-Guindon1" target="_blank">[58]</a> using a JTT+I+G+F model <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003093#ppat.1003093-Jones1" target="_blank">[59]</a> chosen using ProtTest <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003093#ppat.1003093-Abascal1" target="_blank">[60]</a>. Numbers on branches indicate bootstrap support (only values above 70% are shown). The scale bar indicates 0.05 substitutions per site. (<b>C</b>) Comparison of the N1FR2011, 2693BA and YBF30 and N-Vpu protein sequences. As indicated, the N1FR2011 Vpu contains intact AxxxAxxxxxLL, DSGxxS and E/DxxxLL/I/V/M sites and a membrane proximal lysine residue (yellow). Dots specify amino acid identity and dashes gaps introduced to improve the alignment. (<b>D</b>) Efficient interaction of the N1FR2011 Vpu with ß-TrCP. 293T cells were transfected with plasmids expressing Vpu-N-Luc and C-Luc-ß-TrCP fusions and luciferase activity determined as described in the legend of <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003093#ppat-1003093-g004" target="_blank">Figure 4</a>. Shown is the comparison of the luciferase activity obtained for the N1FR2011 Vpu in comparison to group M (n = 3) and N (n = 7) Vpus. Each allele was measured in triplicate and shown are averages ±SDs. (<b>E</b>) Efficiency of downmodulation of tetherin in the presence of constructs expressing the indicated Vpus relative to those measured in cells transfected with the eGFP control vector. Values are averages (±SD) derived from three experiments. (<b>F to H</b>) Comparison of the effect of N1FR2011 and group N (n = 6) or M (n = 3) Vpu proteins on (<b>F</b>) infectious virus production or (<b>G, H</b>) viral p24 antigen release determined by (<b>G</b>) Western blot or (<b>H</b>) ELISA. Values represent the average infection levels or quantities of p24 antigen (n = 3) obtained in the presence of tetherin relative to those obtained in the absence of the restriction factor (100%). Percentages of cell-free p24 were normalized to the levels of cell-associated p24 antigen.