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Immunoprofiling of peripheral blood from infectious bronchitis virus vaccinated MHC-B chicken lines – Monocyte MHC-II expression as a potential correlate of protection

Larsen, Frederik T., Bed’Hom, Bertrand, Naghizadeh, Mohammad, Kjærup, Rikke B., Zohari, Siamak, Dalgaard, Tina S.
Developmental and comparative immunology 2019 v.96 pp. 93-102
Infectious bronchitis virus, chickens, farms, flow cytometry, haplotypes, major histocompatibility complex, monocytes, poultry industry, vaccination, vaccines, viral load
Vaccination programs are implemented in poultry farms to limit outbreaks and spread of infectious bronchitis virus (IBV), which is a substantial economic burden in the poultry industry. Immune correlates, used to predict vaccine efficacy, have proved difficult to find for IBV-vaccine-induced protection. To find correlates of IBV-vaccine-induced protection, hence, we employed a flow cytometric assay to quantify peripheral leucocyte subsets and expression of cell surface markers of six different non-vaccinated and vaccinated Major Histocompatibility Complex (MHC) haplotypes. Non-vaccinated and vaccinated MHC haplotypes presented differential leucocyte composition and IBV viral load. A strong effect of MHC-B, but not vaccination, on several leucocyte subsets resulted in positive correlations with IBV viral load based on MHC haplotype ranking. In addition, a strong effect of MHC-B and vaccination on monocyte MHC-II expression showed that animals with highest monocyte MHC-II expression had weakest vaccine-induced protection. In conclusion, we found several interesting MHC-B related immune correlates of protection and that flow cytometric analysis can be employed to study correlates of IBV-vaccine-induced protection.