Eligible patients were HIV-infected adults ( aged 18 years ) with HIV-1 RNA of less than 50 copies per mL , for at least 6 months on triple treatment with lopinavir-ritonavir ( twice daily ) plus lamivudine or emtricitabine and a second nucleos ( t ) ide , with no resistance or virological failure to these drugs , and no positive hepatitis B serum surface antigen .