A Molecular Clone of Simian-Human Immunodeficiency Virus (ΔvpuSHIVKU-1bMC33) with a Truncated, Non-Membrane-Bound Vpu Results in Rapid CD4+ T Cell Loss and Neuro-AIDS in Pig-Tailed Macaques

Abstract

We report on the role of vpu in the pathogenesis of a molecularly cloned simian-human immunodeficiency virus (SHIVKU-1bMC33), in which the tat, rev, vpu, env, and nef genes derived from the uncloned SHIVKU-1b virus were inserted into the genetic background of parental nonpathogenic SHIV-4. A mutant was constructed (ΔvpuSHIVKU-1bMC33) in which 42 of 82 amino acids of Vpu were deleted. Phase partitioning studies revealed that the truncated Vpu was not an integral membrane protein, and pulse-chase culture studies revealed that cells inoculated with ΔvpuSHIVKU-1bMC33 released viral p27 into the culture medium with slightly reduced kinetics compared with cultures inoculated with SHIVKU-1bMC33. Inoculation of ΔvpuSHIVKU-1bMC33 into two pig-tailed macaques resulted in a severe decline of CD4+ T cells and neurological disease in one macaque and a more moderate decline of CD4+ T cells in the other macaque. These results indicate that a membrane-bound Vpu is not required for the CD4+ T cell loss and neurological disease in SHIV-inoculated pig-tailed macaques. Furthermore, because the amino acid substitutions in the Tat and Rev were identical to those previously reported for the nonpathogenic SHIVPPc, our results indicate that amino acid substitutions in the Env and/or Nef were responsible for the observed CD4+ T cell loss and neurological disease after inoculation with this molecular clone.