Surveillance of HIV drug resistance transmission in Iran: experience gained from a pilot study.

We performed a pilot surveillance study on transmitted HIV drug resistance (TDR) in Iran, with specimens collected and stored as dried blood spots (DBS). The protease region and relevant positions in the reverse transcriptase region of the pol gene were sequenced to detect mutations known to be associated with resistance to drugs in standard first-line regimens. Seventy-three specimens were collected, with 39 (53%) specimens yielding sequence from both protease and at least part of RT. Specimens were almost exclusively HIV-1 subtype CRF 35_A1D based on pol sequencing. Mutations were restricted to RT, with D67DG and V75AV each seen in a single specimen. An atypical protease inhibitor mutation, I47M, appeared at a resistance-associated position in protease from a single specimen. These preliminary data showed that the rate of transmitted drug resistance in Iran, within the areas sampled, was 5.1% (2/39). However, the small sample size makes this figure only an approximation. Due to the sampling strategy and resulting small sample size, we were unable to accurately calculate TDR rates for individual areas using the WHO HIV drug resistance threshold survey method. Increasing the sample size and improving the yield from DBS would improve the accuracy of drug resistance surveillance and facilitate wider application of this methodology in Iran.