RNA amplification of the HIV-1 Pol and env regions on dried serum and plasma spots.

Background: Dried sample spots have molecular applications, but few data are available on conditions of HIV-1 RNA amplification.

Objectives: To determine the impact of (i) the sample type (plasma or serum), (ii) various storage periods, (iii) transfer at ambient temperature of the dried spots via postal mail, and (iv) two different methods of elution-extraction, to amplify partial pol and env genes with a view to both phylogenic and resistance analyses.

Methods: Fourteen samples (dried plasma spot and dried serum spot) from seven patients were stored at 20-25 degrees C for 2, 5 and 7 days. Two extraction buffers were tested on these samples, followed by reverse transcriptase-polymerase chain reaction (RT-PCR) on pol and env genes. Sixteen spots from eight other patients were sent by postal mail at ambient temperature between two laboratories, and were analysed at both sites.

Results: We observed no influence of the 2-7 day storage period, whatever the sample type and viral load, but the choice of the extraction procedure is a critical step. Analysis of the mailed spots resulted in a good agreement between the two laboratories.

Conclusions: This study shows that amplification of HIV-1 RNA on spots is possible in various conditions by different operators and using appropriate reagents. This finding could be particularly useful for large-scale molecular and resistance epidemiological studies in resource-rich and resource-limited countries alike.