- Subject is receiving a once-daily regimen of ATV (300mg) + RTV (100mg) + TDF/FTC (300mg/200mg) for at least 6 months prior to or by the first day of screening. ATV + RTV + TDF/FTC must be the subejct's INITIAL regimen or FIRST or SECOND SWITCH regimen. If ATV + RTV + TDF/FTC is subject's first or second switch regimen, then subject may ONLY have received the following prior regimens: a) any currently licensed non-nucleoside reverse transcriptase inhibitor (NNRTI) + TDF/FTC or ZDV/3TC; b) RTV-boosted PI with TDF/FTC or ZDV/3TC; or c) an alternative regimen not listed above after approval by Sponsor.