Whatman FTA cards versus plasma specimens for the quantitation of HIV-1 RNA using two real-time PCR assays

Background: Several studies have compared the use of dried blot spot (DBS) as an alternative to plasma specimens, mainly using Whatman 903 cards as filter paper. The aim of this study was to evaluate the use of Whatman FTA card (FTA card) specimens for HIV-1 viral load testing compared to plasma specimens using two real-time PCR assays manufactured by Roche and Abbott.
Methodology: A cross-sectional study was conducted between April 2017 and September 2017 on HIV-1 patients admitted to Yalgado Ouédraogo Teaching Hospital. Paired FTA cards and plasma specimens were collected and analysed using the Abbott Real-Time HIV-1 assay (Abbott) and COBAS AmpliPrep/COBAS TaqMan v2.0 (Roche).
Results: In total, 107 patients were included. No statistical differences (P>0.05) were observed between the mean viral loads obtained from the FTA cards and those of the plasma specimens using the Roche and Abbott assays. In total, 29 samples with Roche and 15 samples with Abbott assay showed discrepant results. At viral loads of ≤1000 copies ml-1, the sensitivity and specificity of the FTA cards were 78.6 and 100% with Roche, and 92.3 and 95.9% with Abbott, respectively. Both the Roche and Abbott assays showed good correlation and agreement between the FTA cards and plasma values.
Conclusion: Our study demonstrates the feasibility of using FTA card filter paper for HIV-1 viral load testing. However, further studies will be required https://biodas.org/ for the validation of the use of FTA card filter paper in HIV-1 treatment monitoring.
Stability of Human Immunodeficiency Virus Serological Markers in Samples Collected as HemaSpot and Whatman 903 Dried Blood Spots.
  • Dried blood spots (DBS) are frequently used in clinical testing for biosurveillance, infectious disease and confirmatory testing, and clinical trials, particularly for populations in remote areas. The HemaSpot-HF blood collection device (HS) provides an alternative format to the Whatman 903 cards (903) to simplify sample collection and processing. In this study, the performance of the HS was compared to that of the 903 using previously characterized clinical specimens and HIV seroconversion panels known to exhibit markers of early human immunodeficiency virus (HIV) infection.
  • HS and 903 samples were prepared and tested by Bio-Rad GS HIV Combo Ag/Ab enzyme immunoassay (EIA), GS HIV-1/-2 Plus O EIA, GS HIV-1 Western blot, and HIV-1 Geenius assays. Both HS and 903 performed well for up to 6 months at room temperature, but a marked loss of Western blot and low titer antibody signals from early infection samples was observed in samples stored for 180 days at elevated (37 to 45°C) temperatures and high humidity (95%).
  • HemaSpot samples placed in sealed bags with additional desiccant were protected from degradation and showed improved signal recovery relative to that of the 903. HS was easier to use than the 903 and showed higher sensitivity and reproducibility for early infection samples and improved stability.

Whatman Protein Saver Cards for Storage and Detection of Parasitic Enteropathogens.

Current methods to identify the etiology of diarrhea require laboratory facilities for storage of pathogens, which is often challenging in low-resource settings. This study evaluated the efficacy of a low-cost method for preserving stool specimens for the detection of parasitic enteropathogens using Whatman 903 protein saver cards (Sigma-Aldrich, St. Louis, MO). Stool samples known to be positive by multiplex real-time polymerase chain reaction for Giardia lamblia, Cryptosporidium spp., and Entamoeba histolytica parasites were preserved on 232 Whatman cards.
DNA was then extracted from cards using Chelex and Qiagen extraction protocols, and tested for these parasites using multiplex real-time PCR. We included stool samples known to have a higher parasite load (cycle threshold [ct]-value < 30) and those with a lower parasite load (ct values 30-35). Sensitivities and specificities were determined using DNA extracted directly from whole stool samples using Qiagen kits (QIAGEN, Hilden, Germany). For whole stool samples with ct values < 30, preserved directly on Whatman 903 protein saver cards for Giardia analysis, the sensitivity was 100% for both Qiagen and Chelex DNA extraction.
For E. histolytica, this was 100% for sensitivity for Qiagen and 80% for Chelex DNA extractions, and for Cryptosporidium, this was 80% for Qiagen and 50% for Chelex DNA extraction. The specificity was 100% for all parasites for all extraction procedures. Given the high sensitivity for stool samples with higher parasite loads, we recommend the use of the Whatman 903 protein saver card for preserving fecal specimens for the analysis of Giardia and E. histolytica using Qiagen DNA extractions in low-resource settings.

Comparison of stool collection and storage on Whatman FTA Elute cards versus frozen stool for enteropathogen detection using the TaqMan Array Card PCR assay.

The use of Polymerase Chain Reaction (PCR) assays for pathogen detection in travelers’ diarrhea (TD) field studies is limited by the on-site processing and storage requirements for fecal specimens. The objectives of this investigation were to i) characterize the pathogen distribution in deployed military personnel with TD using the TaqMan® Array Card PCR (TAC) on frozen stool and diarrheal smears on Whatman FTA Elute cards (FTA cards), and to ii) compare TAC detection of enteropathogen targets using smeared FTA cards and frozen stool, using TAC on frozen stool as the ‘reference standard’.
Stool samples, obtained from active duty personnel with acute TD enrolled in a field trial, were smeared onto FTA cards and stored at room temperature. A corresponding aliquot of stool was frozen in a cryovial. FTA cards and frozen stool samples were tested at a central lab, using a customized TAC for detection of TD pathogens. 187 paired frozen stool samples and smeared FTA cards were stored for a median of 712 days (IQR 396-750) before testing. Overall detection rates were 78.6% for frozen stool and 73.2% for FTA cards. Diarrheagenic Escherichia coli were the most common bacteria identified. Using the TAC results on frozen stool as the reference, the overall sensitivity and specificity of TAC on FTA cards was 72.9% and 98.0% respectively.
TAC on FTA cards demonstrated a decrease in sensitivity with increasing frozen stool quantification cycle (Cq) (90.0% in FTA cards with a corresponding frozen stool Cq < 30, and 72.9% in samples with a corresponding frozen stool Cq < 35). Our findings support the use and further development of FTA cards in combination with a quantitative PCR assay for enteropathogen detection in TD field studies.

Detection of anti-hepatitis C virus and hepatitis C virus RNA in dried blood spot specimens using Whatman No. 1 filter paper.

Dried blood spot (DBS) specimen simplifies blood collection, processing, storage and shipment and may reduce the cost of testing for hepatitis C virus (HCV) infection. We wanted to see if DBS using a cheap filter paper is reliable alternative to serum for detection of anti-HCV and HCV RNA.
At a tertiary care hospital in Northeast India, we collected 91 paired DBS and serum specimens from patients at risk of HCV infection from July 2014 to June 2015. DBS was collected on Whatman No. 1 filter paper. After processing, the specimens were subjected to anti-HCV detection by a third-generation Enzyme-Linked Immunosorbent Assay (ELISA). The reactive DBS and serum specimens were further subjected to HCV RNA detection by polymerase chain reaction. The results were analysed in paired screen-positive study design.
Anti-HCV was detected in 9 (9.9%) DBS specimens and 10 (10.9%) serum specimens. There was statistically significant (P < 0.0001) correlation between the optical density values of DBS and serum specimens (Pearson r = 0.9181, 95% confidence interval: 0.8781-0.9453). HCV RNA was detected in 5/9 (55.6%) reactive DBS and 9/10 (90.0%) reactive serum specimens. There was no correlation between HCV RNA levels in the DBS and the serum specimens. The relative sensitivity rate and the relative false-positive rate of DBS anti-HCV ELISA were 0.89 and 1.00, respectively.
DBS using Whatman No. 1 filter paper is quite reliable as serum for detection of anti-HCV. It can be useful in effective surveillance. However, it is not suitable for confirmation of chronic HCV infection.

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