Fig. 1

Interference of C2 phylogenetic origin with Env functionality. a Representation of the different domains of HIV Env. gp120: orange for constant (C1–C5) and blue for variable (V1–V5) regions; for gp41 the different domains are green and purple. FP fusion peptide, HR1 and HR2 heptad repeats 1 and 2, respectively, DSR disulphide bonded region, TMD trans-membrane domain, CT cytoplasmic tail. b Principle of construction of C2 chimeras. The Env providing the backbone (X) is in pale blue, the one providing the insert in red (Y). The resulting chimera is named X C2Y. c Levels of viral entry of vectors carrying a reporter luciferase gene and having a chimerical C2 Env are shown as percentage of the infectivity observed with the corresponding wild type Env. For each independent experiment the percentage of functionality was determined with respect to the corresponding wild type Env, which was run in parallel, and the values used for the graph correspond to the average of these percentages with error bars indicating the standard deviation. n varies between 3 and 9, depending on the sample considered. Left panel chimeras with an Env A backbone, right panel chimeras with a B Env backbone