of drug resistance mutations in HIV-1 patients with early viral rebound during
ongoing combination therapy program
K Soderbarg, with the
Professional Genetics Lab in Uppsala, reported on this study whose objective was
to determine whether drug resistance mutations in the RT and protease genes
could be found in 7 patients which, during ongoing drug therapy, show minor
increases in viral load.
RNA was isolated from samples with as few as 50 copies/ml, after which PCR
amplification was performed. Mutations that are likely to cause drug resistance
were detected in all patients. These mutations were detected early in the
rebound process. Viral loads were as low as between 50 to 500 copies/ml. But in
samples with as few as 50 copies/ml, it was possible to detect mutant viruses.
The authors concluded mutations causing drug resistance are possible to detect
in samples with very low viral load. Therefore, ongoing replication may result
in further development of resistance. Some researchers question the reliability
of mutations observed in individuals with low viral load <50 copies/ml.