Next, dried blood spots were examined and serum antibodies recovered to produce an immunosignature. Again, a strong correlation of antibody activity was seen in the dried blood vs. fresh serum samples. Rates of protein recovery from dried bloodincluding functional antibodies ranged from 78 to 100 percent, in both mouse and human samples. The resulting immunosignatures showed higher fluorescence intensities in the case of fresh serum samples, but the effect was uniform across the array.
Once it was clear that dried samples could be used to produce faithful immunosignatures, the group evaluated the stability of samples stored in a simulated mailing environment, noting that large-scale epidemiological studies and health monitoring via immunosignaturing could be carried out if samples retained potency over time and when exposed to heat.
Samples of dried blood were stored at 25 degrees C or 37.8 degrees C. Immunosignatures remained stable after 2 weeks at the lower temperature. At 37.8 degrees C, samples retained stability overnight, but declined in stability after 2 weeks. As antibodies or immunoglobins are sensitive to bacteria, which may be inadvertently introduced during sample collection or transport, the application of protease inhibitors was subsequently used, and demonstrated an improvement in sample stability. Using dried blood, the team also showed that a characteristic immunosignature could be detected in mice previously infected with influenza, when compared with non-infected controls.
Finally, human saliva was assessed for its ability to provide an acc
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