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The 2009 Influenza A (H1N1) pandemic disproportionately affected the developing world and highlighted the key inadequacies of traditional diagnostic methods that make them unsuitable for use in resource-limited settings, from expensive equipment and infrastructure requirements to unacceptably long turnaround times. While rapid immunoassay diagnostic tests were much less costly and more context-appropriate, they suffered from drastically low sensitivities and high false negative rates. An accurate, sensitive, and specific molecular diagnostic that is also rapid, low-cost, and independent of laboratory infrastructure is needed for effective point-of-care detection and epidemiological control in these developing regions. We developed a paper-based assay that allows for the extraction and purification of RNA directly from human clinical nasopharyngeal specimens through a poly(ether sulfone) paper matrix, H1N1-specific in situ isothermal amplification directly within the same paper matrix, and immediate visual detection on lateral flow strips. The complete sample-to-answer assay can be performed at the point-of-care in just 45 min, without the need for expensive equipment or laboratory infrastructure, and it has a clinically relevant viral load detection limit of 10(6) copies/mL, offering a 10-fold improvement over current rapid immunoassays.

Background: Diseases with an onset during childhood or adult life can have their origin during fetal life or at birth. Neonatal blood dried on filter paper (Guthrie cards) collected for screening purposes is routinely stored for decades. In addition to clinical use, these filters in combination with patient registers constitute an invaluable resource for epidemiological and pathophysiological research. Although RNA has been successfully recovered from such filters even after decades of storage, the potential decay of RNA over time has not previously been investigated using quantitative methods., Methods: Filter papers (n=5) with dried blood spots from the Swedish National PKU register, stored for 1, 5, 10, 15 or 20 years were randomly selected. RNA was isolated from each sample, quantitated by spectrophotometry and reverse transcribed following DNase I treatment. Amplifiable cDNA was subsequently detected by real-time PCR using primers specific for transcripts encoding beta-actin., Results: Transcripts encoding beta-actin were detected in all 25 samples analyzed at a mean threshold cycle (Ct) of 25 (SD 1.9). A one-way ANOVA indicated no significant effect of storage time on Ct values., Conclusions: The lack of significant decay of RNA in dried blood filters stored for up to 20 years suggests that such filters are useful for studies of RNA determinants of diseases with an onset in childhood as well as adult life.

The ability to archive biological samples for subsequent nucleic acid analysis is essential for tissue specimens and forensic samples. FTA Card is a chemically treated filter paper designed for the collection and room temperature storage of biological samples for subsequent DNA analysis. Its usefulness for the preservation of biological samples for subsequent RNA analysis was tested. Here, we demonstrate that RNA in biological samples stored on FTA Cards is stable and can be used successfully for RT-PCR and northern blot analysis. RNA stability depends on the storage temperature and the type of biological specimen. RNA in mammalian cells stored on FTA Cards is stable for over one year at temperatures at or below -20 degrees C and for two to three months in samples stored at room temperature. For plant leaf, longer storage times (> 5 days) require temperatures at or below -70 degrees C following sample application. FTA Cards may constitute a method not only for convenient collection and storage of biological samples but also for rapid RT-PCR analysis of tissue and cell samples.