About ABVIC

Antibody Testing:
a powerful tool for diagnosing viral infections

Key Features of the HSV ABVIC Test

When a person contracts herpes simplex virus 1 or 2 (HSV-1 or HSV-2), the individual’s immune system (white blood cells) generates HSV-specific antibodies within the first four weeks after exposure. Many suspected viral infections, such as HIV or influenza virus, may be diagnosed by testing a patient’s blood for the presence of such virus-specific antibodies.   Enzyme-linked immunosorbent assay (ELISA)-based antibody tests have long existed for HSV-1 or HSV-2 (e.g., Diasorin’s HerpeSelect® Test), but they are prone to yield both false-negative and false-positive results at an unacceptably high frequency. Thus, many physicians avoid herpes antibody tests because they have the potential to confuse and upset patients when the tests yield erroneous results that are inconsistent with the clinical picture. A more accurate herpes antibody test is needed, and at Rational Vaccines we believe the new HSV ABVIC Test addresses many of these problems.  Learn more about a study in which the quantitative HSV ABVIC Test resolved >90% of equivocal antibody test results produced by the qualitative HerpeSelect® and HSV Western Blot methods.

What is ABVIC?
IF-Plaque-Staining-(about_ABVIC-page)(1)ABVIC is a novel flow-cytometry-based method that measures antibody binding to virus-infected cells. When a cell is infected with herpes simplex virus 1 or 2 (HSV-1 or HSV-2), the virus synthesizes about 75 viral proteins. Fixed virus-infected cells can be used to detect antibodies that bind any, or all, of these proteins encoded by HSV-1 or HSV-2. In the setting of immunofluorescent microscopy (adjacent image), HSV-specific antibodies bind to cells in a single HSV-2 plaque and produce a bright red color when labeled with a red-fluorescent antibody that binds human IgG antibody. In contrast, surrounding uninfected (UI) cells at the edges of the image are not bound by HSV-specific antibodies and thus appear black.

flow-cytometry-plot-(about_ABVIC-page)(1)The HSV ABVIC Test relies on a similar principle, but is modified in three ways. First, fixed cells are brought into a suspension before antibody binding is performed. Second, the amount of human IgG antibody bound to fixed cells is measured in a flow cytometer (y-axis of adjacent data plot). Finally, a mixture of (1) uninfected (UI), (2) HSV-1+, and (3) HSV-2+ cells are differentially labeled with green CFSE dye, combined together and mixed with a patient’s blood sample, and antibody binding to each population of cells is measured in a flow cytometer.   Due to the differential CFSE labeling, the three populations of fixed cells spread across the x-axis of a flow cytometry data plot (adjacent image). The background level of non-specific IgG antibody binding to cells is defined by the low cloud of uninfected (UI) cells on the left. In contrast, IgG antibodies in this patient’s blood bind HSV-1+ and HSV-2+ cells to 1-log (10-fold) higher levels than UI cells, which indicates that the individual is HSV-seropositive.

Role of Pre-adsorption in the HSV ABVIC Test

When a person’s blood is evaluated in the HSV ABVIC Test, it is evaluated for the presence of:

  • Total HSV-specific antibody
  • HSV-1-specific antibody, and
  • HSV-2-specific antibody

Pre-Adsorption-Figure-(about-ABVIC-Page)(1)HSV-1 and HSV-2 are similar viruses. A person infected with HSV-1 will have some “type-common” antibodies (shown as blue Y’s in the adjacent image) that may bind HSV-1+ or HSV-2+ cells. Likewise, a person infected with HSV-2 will have “type-common” antibodies that bind HSV-1+ or HSV-2+ cells.

To create a type-specific test that can differentiate whether a person is infected with HSV-1, HSV-2, or both, HSV type-common antibodies must be removed. Enriched populations of HSV-1 specific antibody may be obtained by pre-adsorption to HSV-2+ cells (red Y’s in center column). Reciprocally, enriched populations of HSV-2 specific antibody may be obtained by pre-adsorption to HSV-1+ cells (green Y’s in right column). Click here to learn how easy it is to interpret the results of the HSV ABVIC Test.

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