3.4　Serum HIV RNA Quantitation

Quantitation of HIV RNA in banked serum samples was performed using reverse transcriptase（RT）and the polymerase chain reaction（PCR），as previously described［14，15］.In brief，total RNA was extracted from serum using RNazol（Biotecx Laboratories，Houston，TX）.HIV RNA was reverse transcribed using random hexamers，amplified by PCR，and then detected by oligonucleotide hybridization［15］.Using a standard curve of synthetic HIV RNA，the amount of HIV RNA in serum samples could be quantitated over a linear range from 50 to 1，000 input copies.

Serum samples were analyzed for HIV RNA prior to DNCB sensitization and then two months after sensitization.In addition，HIV RNA quantitation was performed in select cases every two months over the course of the study.(https://www.daowen.com)