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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Exotic & Emerging Avian Viral Diseases Research » Research » Publications at this Location » Publication #432065
Research Project: Control Strategies to Prevent and Respond to Diseases Outbreaks Caused by Avian Influenza Viruses

Location: Exotic & Emerging Avian Viral Diseases Research

Title: Comparative sensitivity of optimized serological assays for detecting and quantifying chicken antibody to avian influenza virus

Author
item LEE, JIHO - Orise Fellow
item Spackman, Erica

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Antibody tests are frequently used to determine whether a poultry flock has ever been infected with avian influenza virus (i.e., bird flu virus). Some veterinary diagnostic laboratories will conduct higher complexity tests to characterize the antibodies to determine whether they are from a "high risk" strain of bird flu virus. The most common test for poultry is called the HI assay but another test called MN assay has been used in public health testing. The MN assay has been shown to be more sensitive than HI assay with human antibodies being tested for seasonal (i.e., the common human flu), however data on MN assay wit poultry antibodies, which have different properties from human antibodies, are lacking. Here the sensitivity for detecting antibodies to bird flu virus by HI assay was compared with two variations of the MN assay using chicken samples. It was found that both variations of the MN assay were more sensitive than the HI assay. Therefore, poultry surveillance programs for bird flu virus can achieve higher sensitivity by using the MN assay.

Technical Abstract: Surveillance programs for low pathogenic avian influenza virus (LPAIV) frequently rely on serological tests to determine whether flocks have been infected with the virus. Poultry sera that are positive by type A influenza screening tests are frequently tested at reference laboratories by hemagglutination inhibition (HI) assay as a subtype specific confirmatory test. Because of the potential to become highly pathogenic, H5 and H7 are the most common targets. An alternative to HI assay is microneutralization (MN) assay, which is widely used for humans and mammalian research animals because of its sensitivity. Subtype specific assays are also used to monitor response to vaccines. Here the sensitivity of HI assay was compared with MN assay using two methods to read the MN assay results, hemagglutination assay (MN-HA) and observation of cytopathogenic effects (MN-CPE). Rates of positivity for individual samples by HI assay, MN-HA and MN-CPE were 66.7% (32/48), 89.6% (43/48), and 87.5% (42/48) respectively. Both MN-HA and MN-CPE were more sensitive than HI assay with a Cohen’s kappa statistic (') of 0.377 for HI versus MN-HA and 0.333 for HI versus MN-CPE where discrepancies were almost exclusively where samples were negative by HI assay and positive by MN-HA or MN-CPE ('=0.897 for MN-HA versus MN-CPE). Titer values were also significantly higher with both MN-HA and MN-CPE than with HI assay (p<0.0001). The highest correlation was between MN-HA and MN-CPE (Pearson’s R value of 0.93), and the correlations were lower between HI assay and MN-HA (Pearson’s R value of 0.77) and between HI assay and MN-CPE (Pearson’s R value of 0.74). Although not significant, there was a trend for MN-HA to produce higher titers and detect more positive samples than MN-CPE.