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Low antibody avidity in elderly chickenpox patients
B D Schoub1, N K Blackburn, S Johnson
1Department of Virology, University of the Witwatersrand, South Africa.
Abstract:
A small outbreak of chickenpox confirmed serologically in 3 elderly patients from a geriatric home is described. Disease was probably due to exogenous reinfection, yet nevertheless the avidity of specific antibodies measured by the urea denaturation test was even lower than in primary chickenpox controls, which themselves were, as expected, significantly lower than zoster controls. In elderly individuals susceptibility to reinfection with varicella-zoster virus (VZV) with clinical manifestation such as chickenpox may well be associated with the decay of specific humoral immunity detectable by antibodies of particularly low avidity, in contrast to reactivation of latent VZV presenting clinically as zoster, which is related to deficiencies in specific cellular immunity.
Insights
Elderly individuals may experience chickenpox reinfection due to declining antibody avidity, indicating weakened humoral immunity. This contrasts with zoster, which is linked to cellular immunity deficiencies in varicella-zoster virus (VZV) reactivation.
Area of Science:
- Immunology
- Virology
- Geriatrics
Background:
- Chickenpox (varicella) is caused by the varicella-zoster virus (VZV).
- Reinfection with VZV can manifest as chickenpox, particularly in susceptible populations.
- Immune system changes in the elderly can affect susceptibility to viral infections.
Purpose of the Study:
- To describe a chickenpox outbreak in elderly patients.
- To investigate the role of antibody avidity in VZV reinfection in the elderly.
- To differentiate immune correlates of VZV reinfection (chickenpox) versus reactivation (zoster).
Main Methods:
- Serological confirmation of chickenpox in three elderly patients.
- Measurement of specific antibody avidity using the urea denaturation test.
- Comparison of antibody avidity in chickenpox patients, primary chickenpox controls, and zoster controls.
Main Results:
- A small outbreak of chickenpox occurred in three elderly patients from a geriatric home.
- Antibody avidity in these reinfection cases was lower than in primary chickenpox controls.
- Antibody avidity in primary chickenpox controls was significantly lower than in zoster controls.
Conclusions:
- Elderly individuals may be susceptible to VZV reinfection (chickenpox) due to decaying humoral immunity, characterized by low-avidity antibodies.
- Zoster in the elderly is associated with deficiencies in cellular immunity, reflecting VZV reactivation.
- Monitoring antibody avidity may help assess susceptibility to VZV reinfection in elderly populations.