Dried Blood Spots for Measuring Vibrio cholerae-specific Immune Responses

Abstract

BackgroundVibrio cholerae causes over 2 million cases of cholera and 90,000 deaths each year. Serosurveillance can be a useful tool for estimating the intensity of cholera transmission and prioritizing populations for cholera control interventions. Current methods involving venous blood draws and downstream specimen storage and transport methods pose logistical challenges in most settings where cholera strikes. To overcome these challenges, we developed methods for determining cholera-specific immune responses from dried blood spots (DBS).Methodology/principal findingsAs conventional vibriocidal assay methods were unsuitable for DBS eluates from filter paper, we adopted a drop-plate culture method. We show that DBS collected from volunteers in South Sudan, and stored for prolonged periods in field conditions, retained functional vibriocidal antibodies, the titers of which correlated with paired serum titers determined by conventional spectrophotometric methods (r = 0.94, p = 0.00012). We also showed that eluates from DBS Serum Separator cards could be used with conventional spectrophotometric vibriocidal methods, and that they correlated with paired serum at a wide range of titers (r = 0.96, p<0.0001). Similarly, we used ELISA methods to show that V. cholerae O-specific polysaccharide antibody responses from DBS eluates correlated with results from paired serum for IgG (r = 0.85, p = 0.00006), IgM (r = 0.79, p = 0.00049) and IgA (r = 0.73, p = 0.0019), highlighting its potential for use in determination of isotype-specific responses. Storage of DBS cards at a range of temperatures did not change antibody responses.ConclusionIn conclusion, we have developed and demonstrated a proof-of-concept for assays utilizing DBS for assessing cholera-specific immune responses.

Estimating cholera incidence with cross-sectional serology

“…Universal protocols for the vibriocidal assays and ELISAs including standard controls such as monoclonal antibodies ( 16 ) may help ensure that numeric values from one laboratory are comparable across other laboratories. Development and validation of highthroughput vibriocidal methods and more field-adapted blood collection methods ( 17 ) will make serologic surveys for cholera more affordable and easier to implement in challenging environments. We highlighted the ability of our models to predict the proportion of the population recently infected in one relatively short epidemic; however, further analyses are needed to understand performance across a suite of epidemic shapes and durations to provide practical guidance for public health decision makers and researchers.…”

Reliability of dried blood spot (DBS) cards in antibody measurement: A systematic review

“…Detection and quantification of antibodies in the serum/plasma, offer a rapid and accurate assessment of vaccine responses. To use serum/plasma samples for serological tests, trained healthcare professionals are required to draw blood [ 2 , 3 ]. As well as a trained professional, there is a need for specific equipment such as vacutainers to collect whole blood and a centrifuge to separate serum/plasma from whole blood.…”

Development of a novel multiplex electrochemiluminescent-based immunoassay to aid enterotoxigenic Escherichia coli vaccine development and evaluations

“…Pre-existing antibody levels against pathogens and toxins are of research interest, as they may positively correlate to eventual disease outcome. Despite conflicting results, it is evident that there is a growing trend in serological studies to establish the correlation between antibody levels and the disease outcome (Trauer et al, 2013), (Iyer et al, 2018), (Broderick et al, 2018).…”