Dried blood spot testing is a microsampling method that has been utilised for qualitative or semi-quantitative analysis of hundreds of molecules, including nucleic acids, elements, small molecule drugs, proteins, enzymes and antibodies (1). When applied to blood testing in humans, DBS boasts many advantages over venous blood draws:

• It allows the collection of small quantities of whole blood via fingertip- or heel prick in a minimally-invasive manner without the need for a phlebotomist, thus improving the patient experience and expanding the possibilities for testing in regions where access to trained phlebotomists is limited.

• Once blood is removed from an individual, it is immediately applied to a pre-prepared DBS filter paper for drying, thereby reducing or even eliminating the need for downstream sample preparation.

• DBS samples can generally be stored and shipped under ambient conditions, which facilitates home- and remote sampling and allows laboratories to receive samples from larger geographical areas than would otherwise be possible.

Capitainer®qDBS – A DBS sampling device that ensures consistent blood volumes every single time

In contrast to conventional DBS, the Capitainer®qDBS microsampling device is designed to prevent oversampling, ensuring accurate blood volumes of 10 µl every single time. The device is very user-friendly with an automatic indicator allowing the user to quickly verify that sampling was successful. Capitainer®qDBS also circumvents the hematocrit (Hct) effect – whereby the proportion of red blood cells (erythrocytes) in the blood influences blood viscosity and may impact the accuracy of analysis – because the integrated DBS filter paper disc is pre-cut prior to blood sampling to perfectly fit the wells of a standard 96-well plate, allowing the entire DBS disc to be used for downstream analysis.

One drop of blood is enough and the sampling card automatically meters and ensures an exact volume of blood is delivered to the quantitative DBS disc.

Capitainer®qDBS has multiple applications within serology

Capitainer’s qDBS device is already being used in a range of research and clinical serological applications, including COVID-19 antibody diagnostics with various analytical platforms.

A systematic literature review published in 2021 indicated that antibodies are stable for several weeks at room temperature in DBS samples, and revealed good correlation between antibody concentrations in DBS and serum/plasma samples (2). These findings support the wider use of DBS in quantitative vaccine and sero-epidemiological studies. The following sections give an overview of some of the ongoing and potential applications for Capitainer®qDBS within serology.

Sero-epidemiology in the pandemic era

As we’ve seen over the last 2 years, sero-epidemiology is a critical tool in research and in public health monitoring to determine the prevalence of certain infectious diseases, to evaluate the impact of transmission control measures and vaccination programmes, and to assess prior infection history within populations when a new virus or variants of an existing virus emerge.

Sero-epidemiology typically involves blood testing to monitor human (or animal) antibodies as biomarkers for ongoing or past infection or immunisation (natural or following vaccination), and is a crucial part of the response to any pandemic or local disease outbreak situation.

While many serology tests are qualitative, e.g., the so-called ‘quick tests’ for COVID-19 that give a yes/no answer, assessing immunisation status by quantifying antibody titers in previously infected or vaccinated individuals is a powerful research and follow-up tool that can be used to improve our understanding of the long-term immune response to infection and vaccination. Such data is important to inform the correct dosing schedule for vaccines in different cohorts, as well as the need for repeat vaccines or boosters.

By ensuring the highest possible sampling accuracy and mitigating the Hct effect, Capitainer’s qDBS device makes quantitative antibody analysis possible.

Home sampling and remote sampling greatly expand the possibilities for sero-epidemiology

Home sampling with an easy-to-use and accurate device such as Capitainer®qDBS allows inclusion of many more individuals in sero-epidemiological measures as it removes geographical distance barriers and eliminates the need to access a phlebotomist.

Early last year, Sweden’s Västerbotten Region began using Capitainer’s qDBS home sampling kit for COVID-19 antibody testing in adults where the samples were analysed at the laboratory Xerum. The setup allowed persons over the age of 16 to order the kit online to be sent to their home address. DBS samples can then be collected at home and posted by regular mail to a lab for analysis. This development was significant given that Västerbotten is Sweden’s second-largest county with a low-density population of 268,000 that is over-represented by elderly people, many of whom are living alone.

The laboratory Xerum has also performed a number of large serological studies with Capitainer. Julia Wigren Bystrom, CEO of Xerum comments: “Large-scale serological testing has been simplified greatly by using Capitainer’s DBS sampling – it’s convenient for the user to do the sampling at home, the successful sampling rate is close to 100% and the laboratory analysis with DBS samples is as accurate as conventional serum analysis.”

Sampling at home is easy and convenient with Capitainer that ensures an exact volume of blood is delivered to the laboratory for quantitative analysis.

Screening for infectious diseases in pregnancy is another major serological application that could benefit greatly from the possibility to perform home and remote sampling. Regardless of the disease in question, the ability to test oneself at home obviously makes it easier for people who live remotely, or have mobility issues for any reason including pregnancy or pre-existing conditions, thereby also reducing the risks associated with not being able to meet up at testing locations.

Broad vaccine development and follow up

The possibility to quantify antibody titers is not only advantageous in a pandemic situation, but also in clinical trials and follow-up studies for vaccines developed against infectious childhood diseases,  tropical diseases, cancer-associated viruses (e.g., human papilloma virus), and others.

Antibody titers can also be important during the development of therapeutic antibodies or any other medical intervention that may impact the immune system.

Academic research

Within research, the applications for antibody titer determination from blood microsamples are almost endless, as long as the antibody detection assays, e.g., ELISA, are compatible with small input volumes.

Examples of applications where serological studies of microsamples could be relevant include: blood proteome research, immunological studies in animal disease models to understand disease mechanisms and/or identify potential targets for immune modulation and early-stage drug development to monitor impact of biological drugs/small molecules/gene silencing/other on antibodies.

Find out more

If you would like to know more about Capitainer®qDBS, and how it might fit into your serology workflow, you are welcome to contact us here to arrange a test or receive a quote.

References

1. Freeman, J., Rosman, L. M., Ratcliff, J. D., Strickland, P. T., Graham, D. R., & Silbrgeld, E. K. (2018). State of he Science in Dried Blood Spots.. Clinical Chemistry, 64(4), 656-679. doi.org/10.1373/clinchem.2017.275966
2. Amini, F., Auma, E., Hsia, Y., Bilton, S., Hall, T., Ramkhelawon, L., Heath, P. T., & Le Doare, K. (2021). Reliability of dried blood spot (DBS) cards in antibody measurement: A systematic review. PloS one, 16(3), e0248218. doi.org/10.1371/journal.pone.0248218