Technology FAQ

What does the SERA Assay identify in samples?

The SERA assay profiles the collection of antibodies to any/all antigens from a given organism, or collection of organisms. SERA identifies the individual epitopes and antigens that are targeted by the immune response and can look broadly across many organisms simultaneously.

What applications can the technology be used for?

The SERA Assay has been successfully employed in various areas including infectious disease, vaccine development, oncology, biomarker discovery.  

Some examples include: 

  • Antibody epitope characterization.
  • Discovery of Motifs/Epitopes associated with disease states.  
  • Identification of autoimmune antigens. 
  • Precision immunology: Identification of acute vs chronic (e.g. Lyme and EBV) and autoimmune subtypes (e.g. Scleroderma).
  • High resolution immune response to profiling to interventions such as vaccines, biotherapeutics, immune tolerance studies etc. 
  • Multiplex/Serosurveillance assessment – tracking changes in infections and autoantigens in individuals over time.

Please visit our publications page to see publications in specific application areas. 

What species can the SERA technology be used with?

We have successfully used the assay with Human, Mouse, NHP, Guinea Pig, Hamster and Canine samples.

Our standard assay utilizes protein A/G beads to capture the IgG, but we can employ alternative custom species-specific binding strategies if the species of interest does not bind to protein A/G.

What samples can be used as starting material for the SERA assay?

The standard starting sample is serum or plasma – but serum is preferred if both are available. We have tested other types of plasma additives (including Streck tubes and Tasso) and seen no difference in performance.

Other body fluids that contain antibodies may also be used such as CSF and synovial fluid, provided a sufficient number of reference control samples are available.

We can also run our assay using purified monoclonal antibodies.

What sort of immunoglobulins is the technology compatible with?

Most of our experience and references have been with IgG isotypes (IgG1, IgG4) but we can also detect IgM and IgA.

How much volume is required?

For serum or plasma samples 50 uL is the minimum sample volume required to complete a project although 100uL is preferred.

For CSF 100uL is the minimum volume required and 200uL is preferred.

For monoclonal antibodies the concentration required depends on desired assay conditions but requires a minimum of 50uL @ 1mg/ml mAb concentration.

If your library is based on peptides, can the SERA technology uncover conformational epitopes or just linear epitopes?

In terms of identifying the conserved immunodominant epitopes, these are predominantly linear. We also identify ‘mimotopes’ that do not map linearly to disease specific antigens, but can serve as biomarkers of exposure/disease. Some of these may represent conformational epitopes.

What percent of the human proteome is covered in your library?

Our library is not based on any proteome and is composed of random peptides which in theory can cover any species and even artificial, non-natural epitopes, and post-translationally modified epitopes. We have a 3X coverage of all possible contiguous 8 aa peptides in our library and all 8mers from the human proteome are represented in our library. The same would be true for other species. This enables the SERA technology to be applied to any eukaryote species, bacteria and viruses.

Is the assay quantitative?

The signals observed in the assay are similar to antibody titers. They are a function of both the strength of the association and the number of antibodies bound. The score for a given epitope is based on both the concentration of the antibody in the sample and the affinity. High affinity antibodies that are at lower concentrations may yield similar epitope enrichments as low affinity antibodies with higher concentrations. That is why the assay is considered semi-quantitative.

Can the assay be used for longitudinal studies?

Yes. The technology can be used to compare and identify changes in an individual’s immune response over time. In vaccination studies we clearly see increases in specific antibodies in response to the vaccine and in longitudinal studies we can measure the change in the magnitude of the signal for each antibody over time. We have also completed longitudinal serosurveillance studies in which we monitor individuals over time and identify when individuals that seroconvert for infections or show biomarkers for specific diseases of interest.

What is the advantage of using SERA over conventional assays such as ELISA and Peptide Arrays?

ELISAs generally measure a polyclonal antibody reactivity to an antigen and cannot identify the specific immunodominant epitopes within the antigen that are targeted by the immune response. While ELISAs are generally more sensitive given the multiple antibodies that contribute to the signal, SERA offers a broader and higher resolution of the immune response at the epitope level. Signals from multiple epitopes and antigens also enables SERA to identify cross-reactive epitopes and improve specificity for a given condition.

Peptide arrays can identify linear epitopes but do not have the broad range of possible sequences that are presented in our random peptide library. They generally require custom production for each organism or antigen of interest and are limited by the total number of features (typically hundreds to thousands of peptides) that can be screened on the array whereas our peptide library has over 10 billion 12 mer peptides.

Protein arrays can identify if antibodies against specific proteins are present but will not provide specific information about which epitopes may be recognized, their sequences or how many potential epitopes are being recognized. Our large population database also enable more robust estimates of specificity of signals relative to peptide and protein arrays.

What bioinformatics analysis do you provide?

There are two main bioinformatics approaches used in conjunction with the SERA assay – IMUNE and PIWAS.

IMUNE analysis provides linear epitope motifs and discontinuous epitope motifs.

PIWAS provides linear epitopes based on selected antigens/proteomes with a ranking of identified antigens at the proteome level. The analysis involves tiling of antigens at the individual level to identify linear epitopes. It can also be used to compare epitopes at the cohort level to compare disease vs control samples.

Titan Infectious Disease Panel – in addition to the bioinformatic discovery analysis we also offer the Titan Diagnostic panel covering over 50 infectious diseases that can be run as a standard analysis on samples.