Yes. I had a T-cell count (CD4+ T-cells, the immune system cells that HIV infects and depletes) of 14, and multiple opportunistic infections (e.g. PCP, M. Kansasii...). This was all off of medication, having never taken medications. At this point, I started on antiviral medication - I have not had a single opportunistic infection since, and my T-cells have not been below 200 in many, many years.
The vast majority of people today who develop AIDS do so in the absence of antiretroviral medications. There is a much smaller number who develop AIDS because they are simply MDR, and there are no medications that can help them (however, most would have died much sooner without medications).