Maternal-derived antibodies hinder the antibody response to H9N2 AIV inactivated vaccine in the field

Xue Pan, Xin Su, Pingyun Ding, Jinhua Zhao, Hongrui Cui, Dawei Yan, Qiaoyang Teng, Xuesong Li, Nancy Beerens, Haitao Zhang, Qinfang Liu, Mart C.M. de Jong*, Zejun Li*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)


The H9N2 subtype avian influenza virus (AIV) inactivated vaccine has been used extensively in poultry farms, but it often fails to stimulate a sufficiently high immune response in poultry in the field, although it works well in laboratory experiments; hence, the virus still causes economic damage every year and poses a potential threat to public health. Based on surveillance data collected in the field, we found that broilers with high levels of maternal-derived antibodies (MDAs) against H9N2 virus did not produce high levels of antibodies after vaccination with a commercial H9N2 inactivated vaccine. In contrast, specific pathogen-free (SPF) chickens without MDAs responded efficiently to that vaccination. When MDAs were mimicked by administering passively transferred antibodies (PTAs) into SPF chickens in the laboratory, similar results were observed: H9N2-specific PTAs inhibited humoral immunity against the H9N2 inactivated vaccine, suggesting that H9N2-specific MDAs might hinder the generation of antibodies when H9N2 inactivated vaccine was used. After challenge with homologous H9N2 virus, the virus was detected in oropharyngeal swabs of the vaccinated and unvaccinated chickens with PTAs but not in the vaccinated chickens without PTAs, indicating that H9N2-specific MDAs were indeed one of the reasons for H9N2 inactivated vaccine failure in the field. When different titers of PTAs were used to mimic MDAs in SPF chickens, high (HI = 12 log2) and medium (HI = log 9 log2) titers of PTAs reduced the generation of H9N2-specific antibodies after the first vaccination, but a booster dose would induce a high and faster humoral immune response even of PTA interference. This study strongly suggested that high or medium titers of MDAs might explain H9N2 inactivated vaccine failure in the field.

Original languageEnglish
Article number9
JournalAnimal Diseases
Issue number1
Publication statusPublished - 6 May 2022


  • H9N2 avian influenza virus (AIV)
  • Humoral immune response
  • Maternal-derived antibodies (MDAs)
  • Passively transferred antibodies (PTAs)
  • Vaccination failure


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