Related Experiment Video
Updated: Jul 14, 2026
06:34
An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers
Published on: December 1, 2017
Hemagglutination Inhibition and Alternate Serologic Responses Following Influenza A(H3N2) Virus Infection
Boshu Chen1, José Victor Zambrana1,2, Abigail Shotwell1
1Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA.
Influenza and Other Respiratory Viruses
|July 12, 2026
Summary
Antibody responses beyond hemagglutination inhibition (HAI) are crucial for influenza immunity. Evaluating diverse antibody targets like HA stalk and neuraminidase (NA) provides a fuller picture of host defense against A(H3N2).
Area of Science:
- Immunology
- Virology
- Epidemiology
Background:
- The hemagglutination inhibition (HAI) titer is the standard measure for influenza protection but doesn't encompass all relevant antibody responses.
- A comprehensive understanding of antibody immunity is essential for accurate influenza surveillance and vaccine development.
Purpose of the Study:
- To investigate immune responses beyond HAI titers in individuals infected with influenza A(H3N2).
- To compare demographic, clinical, and pre-infection antibody characteristics across different response groups.
- To identify predictors of neuraminidase (NA) antibody responses.
Main Methods:
- Analysis of paired sera from 306 RT-PCR-confirmed A(H3N2) infections using HAI and ELISAs against full-length hemagglutinin (HA), HA stalk, and NA.
- Classification of participants into HAI responders, alternate responders (ELISA boost without HAI rise), or no-response individuals.
- Comparison of clinical and immunological data across groups and analysis of NA response predictors.
Main Results:
- 77% of participants showed HAI seroconversion or a fourfold rise.
- Among HAI non-responders (23%), 62% exhibited alternate antibody responses.
- Individuals with no detectable response had high pre-infection HAI/HA titers and milder symptoms.
- Neuraminidase (NA) responses were more frequent in symptomatic individuals with moderate baseline titers.
Conclusions:
- High baseline HAI titers can mask broader immune responses and correlate with less severe illness.
- Assessing diverse antibody targets (HA, HA stalk, NA) offers a more complete view of host immunity to influenza.
- These findings can enhance influenza surveillance and guide future vaccine strategies.
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