Heat-inactivated pooled male AB serum was filtered (0.4 µm filter) and spiked with 200 pg/ml rIL-6.
Cell culture media was prepared from RPMI 1640 supplemented with 2 mM l-glutamine, 100 U of penicillin/mL, 100 µg streptomycin/mL, 10 mM HEPES buffer, and 10% donor serum, and filter sterilized.
ELISA results of serum and filter paper samples were compared by linear regression and calculation of the coefficient correlation.
The reproducibilty of dengue IgM and IgG ELISA was studied in serum and filter paper blood spots from Vietnamese febrile patients.
Dengue virus IgG antibodies in serum and filter papers was not affected by duration of storage, but was subject to inter-laboratory variability.
Agreement between the tests done in the two different laboratories and between serum and filter paper results were analyzed by comparing the positive and negative results and the diagnostic classification based on paired serum samples.
Drying specimens, particularly serum, on filter paper at remote locations, offers a reasonable solution to the problem of hepatitis surveillance in underdeveloped regions, although some attempt at temperature control might be desirable.
The samples were then centrifuged at 400 g and the serum was filtered through a 0.22 μm filter into sterile plastic culture tubes. 100 μL of 99mTc labeled formulations were incubated respectively in 900 μL of this serum (in duplicate) at 37°C and analyzed to check for any dissociation of the complex by ITLC using silica gel strips and 0.9% NaCl aqueous solution (saline) as developing solvent.
The serum was filtered through a 0.45-μm nylon filter (Becton Dickinson, Franklin Lakes, NJ, USA) and stored at 4° C until use [ 19].
After addition of 10 mm DTT, serum was filtered again through a 30 kDa cut-off filter devise (Millipore, Bedford, MA) and the filtrate was precipitated using 25% TCA.
