Testing human sera for antibodies against avian influenza viruses: horse RBC hemagglutination inhibition vs. microneutralization assays.
BACKGROUND
The hemagglutination inhibition (HI) assay is a frequently used method to screen human sera for antibodies against influenza A viruses. Because HI has relatively poor sensitivity in detecting antibodies against avian influenza A strains, a more complicated microneutralization (MN) assay is often preferred. Recent research suggests that the sensitivity of the HI assay can be improved by switching from the traditionally used turkey, guinea pig, human, or chicken RBCs to horse RBCs.


OBJECTIVE
To evaluate the performance of the horse RBC HI when screening for human antibodies against avian influenza types H3, H4, H5, H6, H7, H9, H11, and H12.


METHODS
We evaluated the reproducibility of horse RBC HI and its agreement with MN results using sera from people exposed or not exposed to wild and domestic birds.


RESULTS
The horse RBC HI assay had high reliability (90%-100%) and good agreement with MN assay results (52%-100%).


CONCLUSIONS
The horse RBC HI assay is reliable, less expensive, less complex, and faster than the MN assay. While MN will likely remain the gold standard serologic assay for avian viruses, the horse RBC HI assay may be very useful as a screening assay in large-scale epidemiologic studies.
Center for Emerging Infectious Diseases, Department of Epidemiology, College of Public Health, University of Iowa, Oakdale Research Park, MTF B145, 2501 Crosspark Road, Coralville, IA 52241-8802, United States. ghazi-kayali@uiowa.edu
Ghazi
G
Kayali
Sharon F
SF
Setterquist
Ana W
AW
Capuano
Kendall P
KP
Myers
James S
JS
Gill
Gregory C
GC
Gray
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D001717:Birds; D004912:Erythrocytes; D006168:Guinea Pigs; D006385:Hemagglutination Inhibition Tests / Q000379:methods*; D006736:Horses / Q000097:blood; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D009980:Influenza A virus / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology; D009500:Neutralization Tests / Q000379:methods*; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric
D000914:Antibodies, Viral