Two types of the pathogenic human immunodeficiency virus (HIV), designated HIV-1 and HIV-2, have been characterized. HIV-1 and HIV-2 induce similar clinical courses of infection and yield similar pathogenic characteristics, even though HIV-2 is believed to be less virulent and transmissible than HIV-1. Most HIV infections worldwide are primarily due to HIV-1, whereas HIV-2 is predominant in Western Africa. Amino acid sequence alignment of HIV-1 and HIV-2 yields a homology between 45% and 50%. This fact highlights why some drugs and treatments are very effective towards HIV-1 but have only reduced or no efficacy against HIV-2.
Extensive research has revealed that Vpr is multifunctional and involved in a number of processes during HIV infection. For example, HIV-1 Vpr plays a role in circumventing host immune recognition and supports viral persistence. Vpr also contributes to morbidity and mortality in the course of AIDS. The various key functions of Vpr in the life cycle of HIV indicate that this protein is clearly an attractive target for therapeutic intervention.
In comparison to HIV-1 Vpr, the role of HIV-2 Vpr during infection remains poorly understood. HIV-1 Vpr is known to be cytotoxic and responsible for plasmid instability during expression in E. coli. Such issues lead to unacceptably low yields of recombinant Vpr. In addition, purified HIV-1 Vpr readily aggregates under aqueous conditions, thus severely hampering investigations aimed at elucidating the functions of this protein. We have taken these aspects into account and have developed an expression system that produces a soluble sandwich fusion protein that does not show any cytotoxic effects during expression. Our established purification procedure for HIV-2 Vpr, enables the purification of the protein under purely aqueous buffer conditions. The results provide an ideal platform for functional and structural investigations, and thus the characterization of the important roles HIV-2 Vpr plays during the development of AIDS.
Hänel K, Möckel L, Brummel M, Peiris K, Hartmann R, Dingley AJ, Willbold D, Loidl-Stahlhofen A Expression and purification of soluble HIV-2 viral protein R (Vpr) using a sandwich-fusion protein strategy Prot. Expr. Purific. 95, 156-161 (2014)