HIV infected patients are considered a sort of reservoir having different genetically distinct viral variants (quasispecies), that evolve from the starting virus inoculum. Frequently, during replication, HIV can generate
nucleotide differences in the new viral population; such genetic changes may be uninfluential in viral "fitness" (replication capacity) or give the virus some advantages under a selective pressure, due to immune response or
drug treatment. The use of potent combination
therapy for the treatment of
HIV infections has certainly improved the "quality of life" for patients, decreasing the viral load in the plasma (HIV
RNA). In our study, we investigated whether detection of drug resistance-related mutations was possible in circulating PBMCs, which represent a sort of genetic archive of viral
drug resistances, when the levels of
viral RNA were reduced to below 400 or 50 copies/ml, since, generally, plasma samples with more than 1,000 copies/ml of HIV
RNA are needed to generate some results. The study was successfully performed sequencing proviral HIV
DNA in PBMCs from 32 samples belonging to 25 patients, using a new modified protocol, that showed a good reproduciblity and very interesting data, also in patients with low or without circulating HIV
RNA levels.