Avidity

Detection of low-avidity antibodies (IIFT)

Application example: diagnosis of infectious mononucleosis (detection of low-avidity antibodies against Epstein-Barr virus capsid antigen)
  • Differentiation between low-avidity and high-avidity antibodies 
  • Useful for clarifying diagnostically unclear cases, for example, reactivation, persisting IgM, polyclonal stimulation
  • Important additional marker alongside the anamnesis, clinical symptoms and constallation of specific antibodies (IgA, IgG, IgM)
  • In the immunofluorescence test, the presence of low-avidity antibodies is demonstrated by a much weaker fluorescence on the urea-treated reaction than on the non-urea-treated reaction
  • IIFT products for avidity determination are available for the following parameters:
ProductOrder number
Anti-Toxoplasma gondii IIFTFI 2410 X
Anti-Rubella Virus IIFTFI 2590 X
Anti-Epstein-Barr Virus Capsid Antigen (EBV-CA) IIFTFI 2791 X / FI 2791-2 X
Anti-Epstein-Barr Virus Early Antigen (EBV-EA) IIFTFI 2795 X / FI 2791-2 X
Anti-West-Nile Virus (WNV) IIFTFI 2662 X
Anti-Cytomegalovirus (CMV) IIFTFI 2570 X
Anti-Varicella Zoster Virus (VZV) IIFTFI 2650 X

Detection of low-avidity antibodies (ELISA)

Application example: diagnosis of infectious mononucleosis (detection of low-avidity antibodies against Epstein-Barr virus capsid antigen).
  • Differentiation between low-avidity and high-avidity IgG antibodies
  • Useful for clarifying diagnostically unclear cases, for example, reactivation, persisting IgM antibodies, polyclonal stimulation
  • Important additional marker alongside the anamnesis, clinical symptoms and constellation of specific antibodies (IgA, IgG, IgM)
  • Low-avidity antibodies are present when the extinction measured in ELISA is significantly reduced by treatment with urea. To provide an objective evaluation, the relative avidity index (RAI) is calculated from the values with and without urea treatment.
  • ELISAs for avidity determination are available for the following parameters:
ProductOrder number
Anti-Toxoplasma gondii ELISA (IgG)EI 2410-1 G
Anti-Rubella Virus ELISA (IgG)EI 2590-1 G
Anti-Epstein-Barr Virus Capsid Antigen (EBV-CA) ELISA (IgG)EI 2791-1 G
Anti-West Nile Virus (WNV) ELISA (IgG)EI 2662-1 G
Anti-Cytomegalovirus (CMV) ELISA (IgG)EI 2570-1 G
Anti-Varicella Zoster Virus (VZV) ELISA (IgG)EI 2650-1 G
Anti-Measles Virus ELISA (IgG)EI 2610-1 G
Anti-TBE Virus ELISA (IgG)EI 2661-1 G