Eligibility Criteria:
Inclusion Criteria:
* Prior to any study-related procedures, signed informed consent indicating that they understand the purpose, risks and procedures required for the study and are willing to participate in the study
* Individuals aged 18 to 65 years of age (inclusive) at time of consent
* Documented HIV-1 infection ≥ 6 months prior to Screening 1
* Previous treatment with antiretroviral agents that had a demonstrated suppressive effect (defined as plasma HIV RNA ≤ 50 copies/ml)
* A documented viable ART regimen option, as determined by the Investigator, taking into account prior ART experience and HIV geno/phenotyping analyses
* Not taking antiretroviral therapy for ≥ 6 weeks prior to Screening 1, for one or more of the following reasons:
i) Concerns over short-term or long-term toxicities associated with antiretroviral agents, or ii) Treatment fatigue from the daily regimen of life-long therapy
* Plasma HIV-1 viral RNA ≥ 5,000 copies/mL and ≤ 100,000 copies/ml at Screening 1 and Screening 2
* CD4+ T lymphocyte count ≥ 500 cells/µl at Screening 1 and Screening 2
Exclusion Criteria:
* Abnormal hematology at Screening 1: Absolute neutrophil count (ANC) \< 1.5 x 109/L, Platelet count \< 100 x 109/L, Hemoglobin \< 10 g/dL
* Abnormal biochemistry at Screening 1: Alanine aminotransferase (ALT) \> 2.5 x Upper Limit of Normal (ULN), Total bilirubin \> 1.5 x ULN, Serum creatinine \> 1.5 x ULN
* Detection of any CXCR4-tropic HIV-1 at Screening 1
* Evidence of co-infection with hepatitis B virus, hepatitis C virus, West Nile Virus, or HTLV-1 as detected at Screening 2
* Evidence of active TB infection determined by positive QuantiFERON®-TB Gold/IGRA test result and clinical confirmation at Screening 2
* ART or other antiretroviral therapy within 6 weeks of Screening 1 or any time during the pre-infusion period
* Documented history of CD4+ T lymphocyte count \< 250 cells/µl
* Any previous or current AIDS-defining illnesses (CDC Category C), including AIDS-related dementia, with the exception of Kaposi's sarcoma confined to the skin
* History of malignancy or systemic chemotherapy within the last 5 years (i.e., subjects with prior malignancy must be disease-free for 5 years), except curatively-treated basal cell carcinoma, cutaneous squamous cell carcinoma, or cervical or anal intra-epithelial neoplasia
* History of steroid-dependent asthma in the past 5 years
* History of seizure
* Any clinical history of hematologic diseases including leukemia, myelodysplasia, myeloproliferative disease, thromboembolic disease, sickle cell disorder, thrombocytopenia or leukopenia
* Class II-IV heart failure, according to the New York Heart Association classification
* Inadequate venous access for apheresis, as assessed at Screening 1
* Current or planned systemic immunosuppressive or immunomodulatory medication
* Taking warfarin, aspirin or any medication that is likely to affect platelet function or other aspects of blood coagulation, and unable to safely cease this medication for a period of 1 week prior, during, and 1 week after administration of G-CSF (a total period of 19 days)
* Participation in any study involving any investigational drug or medical device within 30 days prior to Screening 1
* Receipt of a vaccine for HIV-1 or any gene transfer product at any time
* Prior treatment with recombinant G-CSF or busulfan or other stem-cell mobilizing or modulating agent within the previous 12 months
* Known hypersensitivity to busulfan, G-CSF (Neupogen™) or E. coli-derived proteins
* Subjects who will not accept transfusions of blood products
* Pregnant or breast-feeding at any time between Screening 1 and Baseline (infusion)
* History of alcohol or drug abuse within the 12 months prior to Screening 1
* Inability to understand and provide informed consent