Affinity Chromatography Aids Poultry Virus ELISA

Inclusion body hepatitis (IBH) is a liver disease in chickens caused by a group of viruses called fowl adenoviruses, and it can seriously hurt poultry production. Recent data show that one particular strain, known as FAdV-8b, is behind most cases in Thailand. Farmers and veterinarians often rely on a laboratory test that checks chickens' blood for antibodies against a specific strain, but that test is hard to use on a routine basis. To fill this gap, researchers created and tested a new, easier blood test called FAdV-8b-targeted indirect enzyme-linked immunosorbent assay (iELISA) that is designed to detect antibodies against FAdV-8b. To build the test, they used bacteria to make a piece of one of the virus's outer-shell proteins and then purified it with affinity chromatography. A paper based on their work was published in the journal Poultry Science.¹

What Are Fowl Adenoviruses (FAdVs)?

FAdVs are a type of virus that carries its genetic material as DNA and belongs to a family of viruses that infect birds. Unlike some viruses, they don't have an outer fatty coating. Instead, their genetic material is protected only by a hard protein shell. This shell has 20 flat sides, like a tiny soccer ball, and is built mainly from three key proteins called Hexon, Fiber, and Penton base.^2,3 The Hexon protein is involved in immune recognition, the Fiber protein helps the virus attach to host cells, and the Penton base assists with cell entry. These proteins regulate virus-host interactions. The Hexon protein, which contains serotype-specific neutralizing epitopes, is used for FAdV serotype classification based on cross-neutralization assays and genomic characterization of the hexon gene, particularly its hypervariable regions.^4,5

While there is already a similar blood test, also based on the Hexon protein, for a related strain called FAdV-2. The test may not work well for spotting antibodies against FAdV-8b, because the antibodies chickens make usually recognize only the specific strain they were exposed to.⁶This is why a blood test designed specifically for FAdV-8b is needed; it would help track the virus in chicken flocks, check how well vaccines are working, and study how the disease spreads.⁷

How Well Did the New Test Perform?

The researchers used 467 chicken blood samples, all previously checked with the standard antibody test, to fine-tune the new test and see how well it worked. They set a cutoff point to decide which samples counted as positive, and statistical analysis showed that this cutoff did an excellent job of telling infected chickens apart from uninfected ones.¹

Compared with the standard test, the new test correctly identified about 93% of the chickens that had antibodies and about 89% of those that did NOT, so the two tests agreed closely. The new test also did not mistakenly react to blood from chickens exposed to other common poultry diseases or to other strains of the same virus family, including FAdV-2 and FAdV-11. Finally, it gave consistent results whether the same sample was tested several times in one run or across different runs, which shows the test is reliable and precise.¹

“These findings,” write the authors of the paper,¹ “suggest that the rHexon8b iELISA is a rapid, reproducible, and practical serological screening tool for flock-level surveillance, vaccination monitoring, and epidemiological investigation of FAdV-8b-associated IBH in chickens.”

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References

1. Kulprasertsri, S.; Thongnid, M.; Homklinkaew, P. et al. Development and Diagnostic Validation of a Recombinant Hexon L1-based Indirect Enzyme-linked Immunosorbent Assay for Detecting Antibodies to Fowl Adenovirus Serotype 8b in Chickens. Poult Sci. 2026, 105 (12), 107864. DOI: 10.1016/j.psj.2026.107864
2. Hess, M. Detection and Differentiation of Avian Adenoviruses: A Review. Avian Pathol. 2000, 29 (3), 195-206. DOI: 10.1080/03079450050045440
3. Fitzgerald, S. D.; Rautenschlein, S.; Mahsoub, M. H. et al. Adenovirus infections; in Diseases of Poultry (1^st Ed.)D.E. Swayne, D. E.; M. Boulianne, M.; C.M. Logue, C. M. et al. Eds; Wiley, 2020, pp. 321-363.
4. Steer, P. A.; Kirkpatrick, N. C.; O'Rourke, D. et al. Classification of Fowl Adenovirus Serotypes by Use of High-resolution Melting-curve Analysis of the Hexon Gene Region. J Clin Microbiol. 2009, 47 (2), 311-321. DOI: 10.1128/JCM.01567-08
5. Chen, L.; Yin, L.; Zhou, Q. et al. Epidemiological Investigation of Fowl Adenovirus Infections in Poultry in China During 2015-2018. BMC Vet Res. 2019, 15 (1), 271. DOI: 10.1186/s12917-019-1969-7
6. Liu, J.; Mei, N.; Wang, Y. et al. Identification of a Novel Immunological Epitope on Hexon of Fowl Adenovirus Serotype 4. AMB Express. 2021, 11 (1), 153. DOI: 10.1186/s13568-021-01309-2
7. Schachner, A.; Matos, M.; Grafl, B. et al. Fowl Adenovirus-induced Diseases and Strategies for Their Control - A Review on the Current Global Situation. Avian Pathol. 2018, 47 (2), 111-126. DOI: 10.1080/03079457.2017.1385724