CXCR4 tropic or dual tropic virus at screening.

Laboratory values of Grade 3 or greater according to the Modified Division of Microbiology and Infectious Diseases (DMID) Adult Toxicity Tables.

History of Category C AIDS-defining illness according to the 1993 Centers for Disease Control and Prevention (CDC) AIDS surveillance definition.

History of any medical disease or condition that makes the subject (in the opinion of the investigator) unsuitable for the study.

Malignancy within the past 5 years (except for basal carcinomas of the skin and in situ cancers of the cervix).

Females who are pregnant or breastfeeding, or who plan to become pregnant during the study.

Subjects whose dosage or number of prescription medications has changed within 30 days prior to screening

Positive for hepatitis B surface antigen (HBsAg) or antibody to hepatitis C virus (HCV).

Positive alcohol or drug screen

Safety and Efficacy of an Antibody to CCR5 in Individuals With HIV Who Are Not Currently on Antiretroviral Therapy