Immune Status

The need for evaluating the immune status exists in the following areas:

  • Infectious disease screening
  • Vaccine response
  • Autoimmune disorders
  • Allergy testing

ELISA’s are traditionally used to measure the immune status of a serological sample, but these are often very labor intensive, time consuming and frequently require large sample sizes especially when multiple analytes are being analyzed. Multiplex ELISA platforms are available, but are often difficult to customize when developing novel assays. In addition, many of them are not readily adaptable to point of care diagnostic applications due their complexity or the need to accumulate samples in batches before an assay is performed. Fortunately, Axela’s flow through technologies are designed to overcome many of these hurdles by providing the user full automation, high flexibility and a broad dynamic range needed for developing rapid tests for various clinical settings.

Specific applications include:

Multiplex Immunoassays

The diagnosis of an infectious disease is often complicated by the display of identical symptoms caused by different pathogenic organisms. To make a definitive diagnosis, individual assays are needed for each suspected pathogen leading to greater costs and longer result times. A better solution would be a focused multiplex assay that includes detection reagents for specific pathogens that are commonly screened together for a given set of symptoms. For point of care applications, multiple diseases should be assayed on an easy to use platform that provides rapid results on small sample sizes.

At Axela, we have developed serology assays suitable for screening multiple pathogens within a single serum sample. Rapid assays can be performed on a diffractive optics sensor or a protein microarray TipChip. Using diffractive optics, serum samples that are less than 5 uL in volume can be analyzed in less than 30 minutes during a real time immunoassay. A TipChip microarray expressing a set of different infectious disease antigens can analyze up to 8 samples in parallel in about 45 minutes during a fully automated process (see Figure 1 for examples). By using panelPlus™ Technology, custom multiplex panels can also be created on either platform enabling the development of novel infectious disease assays.

Figure 1. (A) Three-plex immunoassay for different parasitic infections analysed by real-time diffractive optics on only 3.5 uL of serum; and (B) Protein microarray featuring eight antigens for the detection of IgG and IgM antibodies.

Literature on Infectious Disease Assays by Axela

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Avidity Measurements

The measurement of antibody avidity has wide spread applications in infectious disease research and vaccine development. For instance, it can be used for determining the level of immunity after vaccination or distinguishing between recent and past infections in patients with diseases where time of infection onset is critical (eg. Toxoplasma gondii infection in pregnant women).

Currently, avidity tests are performed using ELISA’s which require multiple dilutions of the test serum in the presence and absence of a chaotrope to calculate an avidity index. This method is complex, labor intensive and time consuming, making it inappropriate for near patient use. Fortunately, Axela can rapidly and easily measure antibody avidity of a serum sample on both our diffractive optics and flow-through microarray platforms. Diffractive optics, for instance, is capable of measuring both titer and avidity in one integrated assay (See Figure 2).

Figure 2. Real time measurement of both titer and avidity by diffractive optics.

Literature on Titer and Avidity Assays by Axela

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Direct Pathogen Detection

The ability to detect intact viral and bacterial pathogens from crude samples has sig­nificant applications both in food and environmental analysis as well as in clinical diagnos­tics. Most current methods for pathogen detection require culturing the pathogen to increase their number and amplifying its genome by polymerase chain reaction (PCR). These methods are labor intensive, expensive and often need to be performed by highly skilled personnel working in specialized laboratory facilities. Therefore, there is a need for rapid and easy to use pathogen detection tools in order to accelerate the diagnosis of infected patients at the point of care, or to locate the source of contamination in the en­vironment to control outbreaks.

The use of diffractive optics technology is well suited for the detection of unicellular pathogens due to the relatively large sizes of the analytes being assayed and its ability to handle crude samples, eliminating the need for laborious sample preparations. To demonstrate the use of diffractive optics in patho­gen detection, a series of real time immunoassays were developed on the dotLab® System on a variety of crude samples containing clinically relevant viral and bacterial pathogens. Examples of these assays are described in the literature listed below.

Literature on Direct Pathogen Detection by Axela.

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