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Updated: Jun 21, 2026
An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers
Published on: December 1, 2017
Laboratory-based assessment of influenza in German ambulant patients from 1998 to 2008
E Terletskaia-Ladwig1, M Eggers, S Meier
1Labor Prof. Gisela Enders und Partner und Institut für Virologie, Infektiologie und Epidemiologie e.V, Stuttgart, Germany. ladwig@labor-enders.de
Background:
In Germany, the cost for PCR diagnosis of influenza in ambulant patients was not covered by the national statutory health insurance system until 2008. Therefore, cell culture was the standard method applied for routine diagnosis. We have prospectively compared a 1-day rapid cell culture assay (RCA) with conventional cell culture (CCC) during the influenza seasons from 1997/1998 to 2007/2008 and with real-time PCR analysis during the influenza seasons 2003/2004 and 2006/2007.
Patients And Methods:
This study is based on 4,262 respiratory samples obtained from ambulant patients between January 1998 and May 2008. The RCA was performed in microtiter plates that were stained with monoclonal antibodies to influenza virus A and B 16 h after inoculation.
Results:
A total of 1,221 specimens were found to be positive by the cell culture methods - 1,143 (93.6%) by the RCA and 1,012 (82.9%) by the CCC. The sensitivity of the RCA and CCC versus PCR was 75.4% (221/293) and 58% (170/293), respectively. The specificity of both cell culture assays versus PCR was 100%. Influenza A represented 79.3% of the cases diagnosed. An increased activity of influenza was observed between January and March, with the rate of influenza-positive cases being highest for kindergarten and school-aged children.
Conclusion:
While PCR is the most sensitive assay for the diagnosis of influenza, the RCA can still be used for diagnosis and surveillance of this disease. Based on our findings and given the known fact that influenza antibodies reach a plateau 2-4 weeks after immunization, the optimal time for vaccination in Germany is from October through November. Kindergarten and school-aged children represent an important reservoir of infection. Consequently, routine immunization should be considered for this age group to prevent the spread of influenza.
Insights
Rapid cell culture assay (RCA) shows high sensitivity and specificity for influenza diagnosis, offering a viable alternative to conventional methods. This rapid method is effective for influenza surveillance and diagnosis in ambulant patients.
Area of Science:
- Virology
- Infectious Diseases
- Diagnostic Microbiology
Background:
- Influenza diagnosis in Germany relied on cell culture before 2008 due to PCR costs.
- Conventional cell culture (CCC) was the standard diagnostic method for influenza in ambulant patients.
- This study evaluated diagnostic methods for influenza from 1997 to 2008.
Purpose of the Study:
- To compare the diagnostic performance of a rapid cell culture assay (RCA) against conventional cell culture (CCC) and real-time PCR.
- To assess the utility of RCA for influenza diagnosis and surveillance in ambulant patients.
- To determine the optimal timing for influenza vaccination in Germany.
Main Methods:
- Prospective comparison of RCA, CCC, and real-time PCR using 4,262 respiratory samples from ambulant patients.
- RCA involved staining with monoclonal antibodies 16 hours post-inoculation.
- Data collected during influenza seasons from 1997/1998 to 2007/2008.
Main Results:
- RCA detected 93.6% of positive cases, while CCC detected 82.9%.
- RCA sensitivity was 75.4% and CCC sensitivity was 58% compared to PCR.
- Both RCA and CCC demonstrated 100% specificity; Influenza A was the predominant strain, and children were a key reservoir.
Conclusions:
- Rapid cell culture assay (RCA) is a sensitive and specific method for influenza diagnosis and surveillance.
- PCR remains the most sensitive diagnostic assay, but RCA offers a practical alternative.
- Vaccination from October to November is optimal, and routine immunization for children is recommended to curb influenza spread.
