Molecular diagnosis of HIV.

The development of molecular techniques that access viral load and the development of genotypic resistance have revolutionized the treatment of HIV disease. Commercially available viral load assays use a number of different approaches from reverse transcriptase PCR to amplification of branched chain DNA. The drawbacks of the assay are that there is no international standard that allows comparison of viral load between assays and the diversity of different clades of HIV results in the under or the nondetection of some patients samples. New real-time PCR assays are under development, including LightCycler- and TaqMan-based tests. The development of sequence-based genotyping assays for the detection of mutations associated with the development of the resistance to the 17 licensed drugs targeted against the pol gene of HIV have added to the improvements in patient management. However, next-generation assays must extend detection to include the gp41 fusion region and the integrase region of the genome as compounds directed against these targets move from clinical trails into licensed drugs. Also, genotypic assays must improve detection of minor species and detection of sequences from patients with low viral load number. Real-time sequence based-diagnostics remains a realistic target within the next 5 years.