Immunopathogenesis of infectious bronchitis virus Q1 in specific pathogen free chicks

Preparation of polyclonal antibodies to the chicken Beclin1 protein and its application in the detection of nephropathogenic infectious bronchitis virus

Beclin1, also known as ATG6, has been shown to be closely related to coronavirus, however, the link between Beclin1 and nephropathogenic infectious bronchitis virus (NIBV) has been poorly investigated and there are no available antibodies specifically targeting the chicken Beclin1 protein. The study aimed to prepare and assay a polyclonal antibody to Beclin1, enabling a deeper understanding of the mechanism of action of Beclin1 in NIBV. In this study, we amplified the chicken Beclin1 target gene and constructed a recombinant plasmid using prokaryotic expression techniques, then obtained the recombinant target protein by induced expression. Finally, the serum is obtained by immunizing rabbits with the purified and concentrated protein. The results show that the antiserum potency of the ELISA assay was >1:204800. By western blotting and immunofluorescence, the antibodies we prepared specifically recognized the chicken Beclin1 protein, which is mainly found in the nucleus of trachea, lung, kidney, spleen and fabricant cells. NIBV infection significantly decreased the expression of Beclin1 in the trachea, but increased in others. We have successfully prepared specific rabbit anti-chicken Beclin1 polyclonal antibodies, and detected changes in tissues of diseased chickens infected with NIBV, laying the foundation for further studies on the role of Beclin1 in avian diseases.

Evaluation of protection and immunity induced by infectious bronchitis vaccines administered by oculonasal, spray or gel routes in commercial broiler chicks

Broiler chicks' responses following combined IBV live attenuated Massachusetts and 793B strains through gel, spray or oculonasal (ON) vaccination routes were cross-compared. Subsequently, the responses following IBV M41 challenge of the unvaccinated and vaccinated groups were also assessed. Post-vaccination humoral and mucosal immune responses, alongside viral load kinetics in swabs and tissues, were determined using commercial ELISA assays, monoclonal antibody-based IgG and IgA ELISA assays and qRT-PCR respectively. After challenged with IBV-M41 strain, humoral and mucosal immune responses, ciliary protection, viral load kinetics, and immune gene mRNA transcriptions between the three vaccination methods were examined and compared. Findings showed that post-vaccinal humoral and mucosal immune responses were similar in all three vaccination methods. Post vaccinal viral load kinetics is influenced by method of administration. The viral load peaked in the ON group within the tissues and the OP/CL swabs in the first and third weeks respectively. Following M41 challenge, ciliary protection and mucosal immune responses were not influenced by vaccination methods as all three methods offered equal ciliary protection. Immune gene mRNA transcriptions varied by vaccination methods. Significant up-regulation of MDA5, TLR3, IL-6, IFN-α and IFN-β genes were recorded for ON method. For both spray and gel methods, significant up-regulation of only MDA5 and IL-6 genes were noted. The spray and gel-based vaccination methods gave equivalent levels of ciliary protection and mucosal immunity to M41 virulent challenge comparable to those provided by the ON vaccination. Analysis of viral load and patterns of immune gene transcription of the vaccinated-challenged groups revealed high similarity between turbinate and choanal cleft tissues compared to HG and trachea. With regards to immune gene mRNA transcription, for all the vaccinated-challenged groups, similar results were found except for IFN-α, IFN-β and TLR3, which were up-regulated only in ON compared to gel and spray vaccination methods.

Evolution of developmental and comparative immunology in poultry: The regulators and the regulated

Avian has a unique immune system that evolved in response to environmental pressures in all aspects of innate and adaptive immune responses, including localized and circulating lymphocytes, diversity of immunoglobulin repertoire, and various cytokines and chemokines. All of these attributes make birds an indispensable vertebrate model for studying the fundamental immunological concepts and comparative immunology. However, research on the immune system in birds lags far behind that of humans, mice, and other agricultural animal species, and limited immune tools have hindered the adequate application of birds as disease models for mammalian systems. An in-depth understanding of the avian immune system relies on the detailed studies of various regulated and regulatory mediators, such as cell surface antigens, cytokines, and chemokines. Here, we review current knowledge centered on the roles of avian cell surface antigens, cytokines, chemokines, and beyond. Moreover, we provide an update on recent progress in this rapidly developing field of study with respect to the availability of immune reagents that will facilitate the study of regulatory and regulated components of poultry immunity. The new information on avian immunity and available immune tools will benefit avian researchers and evolutionary biologists in conducting fundamental and applied research.

Route of infectious bronchitis virus vaccination determines the type and magnitude of immune responses in table egg laying hens

Chicken immune responses to infectious bronchitis virus (IBV) vaccination can depend on route of administration, vaccine strain and bird age. Typically for layer chickens, IBV vaccinations are administered by spray in the hatchery at day-old and boosted at intervals with live vaccines via drinking water (DW). Knowledge of live attenuated IBV vaccine virus kinetics and the immune response in egg-laying hens is exceptionally limited. Here, we demonstrated dissemination of vaccine viruses and differences in hen innate, mucosal, cellular and humoral immune responses following vaccination with Massachusetts or 793B strains, administered by DW or oculonasal (ON) routes. Detection of IBV in the Mass-vaccinated groups was greater during early time-points, however, 793B was detected more frequently at later timepoints. Viral RNA loads in the Harderian gland and turbinate tissues were significantly higher for ON-Mass compared to all other vaccinated groups. Lachrymal fluid IgY levels were significantly greater than the control at 14 days post-vaccination (dpv) for both vaccine serotypes, and IgA mRNA levels were significantly greater in ON-vaccinated groups compared to DW-vaccinated groups, demonstrating robust mucosal immune responses. Cell mediated immune gene transcripts (CD8-α and CD8-β) were up-regulated in turbinate and trachea tissues. For both vaccines, dissemination and vaccine virus clearance was slower when given by DW compared to the ON route. For ON administration, both vaccines induced comparable levels of mucosal immunity. The Mass vaccine induced cellular immunity to similar levels regardless of vaccination method. When given either by ON or DW, 793B vaccination induced significantly higher levels of humoral immunity.