HIV Vpr: Roles in Viral Replication and Cellular Metabolism

The auxiliary/non-structural proteins of HIVcan be categorized into 2 groups, essential (Tat and Rev) and accessory (Vpr, Vpx, Vif, Vpu, and Nef). HIV replicates competently in vitro in T-cell lines without the need for accessory gene functions (Subbramanian and Cohen, 1994). However, in primary lymphocytes and macrophages, accessory gene products such as Vpr and Vpx contribute to the efficient progression of the virus lifecycle (Balliet et al., 1994; Balotta et al., 1993; Connor et al., 1995; Kwamura et al., 1994; Park and Sodroski, 1995). Furthermore, in vivo there must be a selection pressure directed towards preserving these accessory genes since many primary HIV-1 isolates maintain these reading frames open.