Extension study for participants currently participating in Protocols ACH443-015 and ACH443-018.

Human immunodeficiency virus (HIV)-1-infected, clinically stable, treatment-naïve adult participants who have completed 96 weeks of elvucitabine therapy and whose HIV ribonucleic acid (RNA) levels remain below 50 copies/milliliter (mL) at the 92-week assessment in Protocol ACH443-015 or participants who have completed 48 weeks of elvucitabine therapy and continue to maintain an HIV-1 RNA viral load below their baseline level upon entry into Protocol ACH443-018.

Inclusion Criteria:

• Participants must have successfully completed 96 weeks of elvucitabine therapy in Protocol ACH443-015 or participants have completed 48 weeks of elvucitabine therapy in Protocol ACH443-014A-018 .

Exclusion Criteria:

• Participant has experienced virologic rebound as defined in Section 5.6.1.3 of Protocol ACH443-015.
• Participant has exceeded their Baseline HIV-1 RNA level by Week 44 as measured in Protocol ACH443-014A-018
• Participant is experiencing a drug-related Grade 3 or 4 rash or a drug-related Grade 3 or 4 laboratory toxicity other than Grade 3 or 4 cholesterol, triglyceride, creatinine kinase, or lactate dehydrogenase (LDH).