This study is a 96-week study designed to evaluate the safety and efficacy of GW873140 in combination with Combivir in HIV infected, untreated subjects.

A Phase IIb, 96 week, randomized, partially double-blinded, multicenter, parallel group, repeat dose study to evaluate the safety, tolerability, pharmacokinetics and antiviral effect of GW873140 in combination with Combivir (lamivudine and zidovudine) upon selected immunological and virological markers of HIV-1 infection in antiretroviral therapy naive adults

Inclusion criteria:

• HIV infected subjects.
• Females must be of either non-childbearing age, or have a negative pregnancy test.
• All subjects participating in this study should be counseled on the practice of safe sex using a proven double barrier method of contraception throughout the study.
• Screening lab result of plasma HIV-1 RNA greater than or equal to 10,000 copies/mL and CD4 cell count greater than or equal to 100 cells/mm3.
• Have CC Chemokine Receptor5-tropic (R5-tropic) virus based on viral tropism test at screening visit.
• Have no drug resistance mutations in HIV-1 Reverse Transcriptase based on resistance test at screening visit.
• Be treatment-naive, defined as less than or equal to 2 weeks of treatment with a protease inhibitor (PI) or a nucleoside reverse transcriptase inhibitor/nucleotide reverse transcriptase inhibitor (NRTI/ NtRTI), or less than or equal to 7 days of therapy with a non-nucleoside reverse transcriptase inhibitor (NNRTI).
• Prior treatment with any entry inhibitor, attachment inhibitor, or fusion inhibitor (experimental or approved) is not allowed.
• Be able to understand and follow with protocol requirements, instructions and protocol-stated restrictions.
• Signed and dated written informed consent prior to study entry.

Exclusion criteria:

• Detection of any CXC Receptor4-tropic (X4-tropic) virus, based on viral tropism test at screening.
• Any drug resistance mutations in HIV-1 Reverse Transcriptase based on resistance test at screening visit.
• Active Class C AIDS-defining illness.
• Laboratory abnormalities at screen.
• Significant blood loss prior to study start.
• Pregnant or breastfeeding women.
• Additional qualifying criteria to be determined by the physician.