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Article

Vaccination against the Protozoan Parasite Histomonas meleagridis Primes the Activation of Toll-like Receptors in Turkeys and Chickens Determined by a Set of Newly Developed Multiplex RT-qPCRs

1
Clinic for Poultry and Fish Medicine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, 1210 Vienna, Austria
2
Christian Doppler Laboratory for Innovative Poultry Vaccines (IPOV), University of Veterinary Medicine, 1210 Vienna, Austria
*
Author to whom correspondence should be addressed.
Academic Editors: Caterina Lupini and Elena Catelli
Vaccines 2021, 9(9), 960; https://doi.org/10.3390/vaccines9090960
Received: 4 June 2021 / Revised: 14 August 2021 / Accepted: 23 August 2021 / Published: 27 August 2021
(This article belongs to the Special Issue Poultry Vaccines)
Histomonosis in turkeys and chickens is caused by the extracellular parasite Histomonas meleagridis, but the outcome of the disease varies depending on the host species. So far, studies on the immune response against histomonosis focus mainly on different traits of the adaptive immune system. Activation of toll like receptors (TLR) leads to the interplay between cells of innate and adaptive immunity with consequences on B and T cell clonal expansion. Therefore, the present investigation focused on the interaction of virulent and/or attenuated histomonads with the innate immune system of turkeys and chickens at 4, 10, 21 days post inoculation. The expression of TLRs (TLR1A, 1B, 2A, 2B, 3, 4, 5, 6(Tu), 7, 13(Tu) and 21(Ch)) and pro-inflammatory cytokines (IL1β and IL6) were analysed in caecum and spleen samples by RT-qPCR. Most frequent significant changes in expression levels of TLRs were observed in the caecum following infection with virulent parasites, an effect noticed to a lower degree in tissue samples from birds vaccinated with attenuated parasites. TLR1B, 2B and 4 showed a continuous up-regulation in the caecum of both species during infection or vaccination, followed by challenge with virulent parasites. Vaccinated birds of both species showed a significant earlier change in TLR expression following challenge than birds kept non-vaccinated but challenged. Expression of TLRs and pro-inflammatory cytokines were associated with severe inflammation of diseased birds in the local organ caecum. In the spleen, changes in TLRs and pro-inflammatory cytokines were less prominent and mainly observed in turkey samples. In conclusion, a detailed comparison of TLRs and pro-inflammatory cytokines of the innate immune system following inoculation with attenuated and/or virulent H. meleagridis of two avian host species provides an insight into regulative mechanisms of TLRs in the development of protection and limitation of the disease. View Full-Text
Keywords: pro-inflammatory cytokines; extracellular pathogen; innate immune response; poultry; blackhead disease; histomonosis pro-inflammatory cytokines; extracellular pathogen; innate immune response; poultry; blackhead disease; histomonosis
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MDPI and ACS Style

Mitra, T.; Bramberger, B.; Bilic, I.; Hess, M.; Liebhart, D. Vaccination against the Protozoan Parasite Histomonas meleagridis Primes the Activation of Toll-like Receptors in Turkeys and Chickens Determined by a Set of Newly Developed Multiplex RT-qPCRs. Vaccines 2021, 9, 960. https://doi.org/10.3390/vaccines9090960

AMA Style

Mitra T, Bramberger B, Bilic I, Hess M, Liebhart D. Vaccination against the Protozoan Parasite Histomonas meleagridis Primes the Activation of Toll-like Receptors in Turkeys and Chickens Determined by a Set of Newly Developed Multiplex RT-qPCRs. Vaccines. 2021; 9(9):960. https://doi.org/10.3390/vaccines9090960

Chicago/Turabian Style

Mitra, Taniya, Beatrice Bramberger, Ivana Bilic, Michael Hess, and Dieter Liebhart. 2021. "Vaccination against the Protozoan Parasite Histomonas meleagridis Primes the Activation of Toll-like Receptors in Turkeys and Chickens Determined by a Set of Newly Developed Multiplex RT-qPCRs" Vaccines 9, no. 9: 960. https://doi.org/10.3390/vaccines9090960

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