Growth properties of macaque-tropic HIV-1 clones carrying vpr/vpx genes derived from simian immunodeficiency viruses in place of their vpr regions

We have previously generated a macaque-tropic human immunodeficiency virus type 1 (HIV-1mt) clone designated MN4/LSDQgtu by genetic manipulation from a parental virus that replicates poorly in rhesus macaque cells. In rhesus cell line M1.3S and peripheral blood mononuclear cells (PBMCs), MN4/LSDQgtu grows comparably to a standard simian immunodeficiency virus clone derived from the rhesus macaque (SIVmac239) that can induce the acquired immunodeficiency syndrome (AIDS) in the animals. In this study, we further modified the Vpr-coding region of MN4/LSDQgtu genome by introducing vpr gene of an SIV clone from the greater spot-nosed monkey (SIVgsn166) or vpx gene of SIVmac239 to generate four new clones for determining functional importance of the central genomic area. Furthermore, two clones with an additional Gag-p6 mutation were made to ensure the virion-packaging of Vpx. In addition, accessory gene mutant clones of MN4/LSDQgtu with a frame-shift mutation, including a vpr mutant, were constructed and their growth properties were examined. Infection experiments showed that newly constructed viruses all grew poorly to various degrees in M1.3S cells, relative to MN4/LSDQgtu. Together with the previous data, our results here show that vpr/vpx gene in the appropriate context of HIV-1 genome is critical for viral growth ability.