Infectious bronchitis virus (IBV) causes infectious bronchitis disease in chickens. IBV primarily infects the upper respiratory tract and then disseminates to other body systems including gastrointestinal, reproductive, and urinary systems. Unlike original IBV serotypes, the novel IBV variants target lymphoid organs, but information on this is scarce. In this study, we aim to evaluate the impact of the presence of maternal antibodies on IBV infection in primary and secondary lymphoid organs. Maternal antibody free, specific pathogen free (SPF) hens were divided into vaccinated and non-vaccinated groups. The progeny male chicks from these hens were divided into four groups; vaccinated challenged (VC), non-vaccinated challenged (NVC), vaccinated non-challenged (VNC), and non-vaccinated non-challenged (NVNC). The challenge groups were given 1 × 10⁶ embryo infectious dose (EID)₅₀ of IBV Delmarva (DMV)/1639 by the oculo-nasal route and non-challenge groups were given saline. The serum anti-IBV antibody titer was significantly higher in challenged groups compared to non-challenged groups. The IBV genome load was significantly lower in the VC group than NVC group in oropharyngeal and cloacal swabs and in bursa of Fabricius (BF) and cecal tonsils (CT). The histopathological lesion scores were significantly lower in VC group than NVC group in BF and CT. These findings suggest that the presence of maternal antibody in chicks could provide some degree of protection against IBV infection in BF and CT.

Infectious bronchitis virus (IBV) poses a major challenge to poultry health and productivity. This study examined how inflammatory cell death pathways influence the replication and pathogenesis of two IBV strains—respiratory Connecticut (Conn) A5968 and nephropathogenic Delmarva (DMV)/1639—in chicken macrophages. Low serum conditions enhanced viral replication, reduced cell viability, and promoted apoptosis and necroptosis, with DMV/1639 showing more pronounced effects. Modulation of the cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2) pathway displayed strain-specific effects, mitigating necroptosis in DMV/1639-infected cells but exacerbating apoptosis and necroptosis in Conn A5968-infected cells. Broad caspase inhibition (z-VAD-FMK) reduced necroptosis, while selective caspase-1/4 inhibition heightened apoptotic responses. Caspase-8 inhibition selectively reduced necroptosis in DMV/1639 infections but increased apoptosis and necroptosis in Conn A5968 infections. NLRP3 inflammasome and RIPK1 inhibition decreased cell viability and increased apoptosis in both strains but had distinct effects on necroptosis. These findings reveal the strain-specific regulation of viral replication, apoptosis, and necroptosis, underscoring the intricate interplay between IBV and host inflammatory pathways. Understanding these mechanisms provides novel insights into IBV pathogenesis and highlights potential therapeutic strategies to mitigate its impact on poultry health.

Drinking water quality is a critical factor in poultry production, and suboptimal drinking water can negatively influence immune functions leading to reduced vaccine efficacy. In the field study, we assessed drinking water quality on Alberta layer farms and evaluated its impact on vaccine-induced immune responses. Chemical, physical and microbiological analyses were performed on 26 water samples collected from Alberta layer farms and serological response for poultry viral vaccines were evaluated at the same time. The water hardness, pH, bicarbonates, and dissolved sodium exceeded acceptable limits in 34 %, 50 %, 46 %, and 27 % of the farms, respectively. Farm-level data revealed no significant direct correlation between water quality scores and vaccine induced serological response. For the controlled experiment, specific pathogen-free White Leghorn chicks were assigned to 4 groups: tap water control (TW-control), field water control (FW-control), tap water vaccinated (TW-vaccinated), and field water (FW-vaccinated), two of the groups were vaccinated against infectious bronchitis while maintaining unvaccinated controls and all 4 groups were maintained on their respective water sources for ∼8 weeks. Controlled experiments showed that vaccinated birds receiving FW had 600 units lower mean antibody titers compared to those given TW, which is statistically not significant. The vaccinated FW group also showed reduced CD4⁺ and CD8⁺ T-cell populations in the spleen and lungs, along with altered IFN-γ and significantly increased IL-10 transcription. In conclusion, although the field data showed a lack of correlation between water quality and vaccine induced serological response, the control experiment revealed that poor water quality might influence the infectious bronchitis vaccine effectiveness in layers.

This study investigated the impact of poor drinking water quality on infectious bronchitis virus (IBV) pathogenesis. Drinking water samples from Alberta layer farms were assessed based on physical, chemical, and microbiological properties. The highest-scoring field water (FW), which is suboptimal with higher pH, hardness and bicarbonate concentration was selected, transported in clean containers, and used in this control experiment. Forty-eight specific pathogen free White Leghorn chicks were divided into four groups: Tap water non-infected (TW-control), field water non-infected (FW-control), tap water infected (TW-infected), and field water infected (FW-infected). They were maintained on their respective water types for 7 weeks. The IBV genome load was significantly higher in the lungs of the FW-infected when compared to TW-infected group at 4 days post-infection (dpi). The histopathological lesion scores in the trachea and lungs were higher in the FW-infected birds when compared to the uninfected controls at observed time points. However, the histopathological lesion scores in the trachea and lungs of the TW-infected birds were not different when compared to that of FW-infected group. In the lungs, the CD4 + and CD8 + T cell populations were significantly higher in the TW-infected group at observed time points when compared to uninfected controls. However, the CD4 + and CD8 + T cell populations in lungs of the FW-infected birds were not different when compared to that of TW-infected group. In the spleen, CD4 + and CD8 + T cell populations were significantly higher in TW-infected and FW-infected birds when compared to uninfected controls depending on the observed time point and we did not observe differences in CD4 + and CD8 + T cell populations in spleen between TW-infected and FW-infected birds. These findings suggest that sub-optimal drinking water can exacerbate IBV infection by weakening immune responses and increasing disease severity. Further studies are necessary to observe the effect of suboptimal water quality on the development of vaccine-mediated immune response. Understanding these interactions is key for improving water management strategies for maintaining poultry health and productivity.

Culture-independent techniques are playing a major role in exploring unique and novel microbial communities from complex ecosystems, leading to an outstanding impact on our basic understanding of the tree of life. Microbial communities are not extensively studied in layer chicken housing environments, particularly from the point of view of taxa carrying antimicrobial resistance genes, virulence genes and their functional potential. This study aimed to extract metagenomic-assembled genomes (MAGs) from the Illumina short-reads shotgun metagenomics sequenced data that originated from an Alberta poultry barn environment and then to study host tracking of antimicrobial resistance genes (ARGs) and the roles of genes involved in functions related to ammonia production, short-chain fatty acid (SCFA)-related pathways, sulfur metabolism, methane emission, stress and disinfectant-related pathways. A total of 251 high-quality MAGs were extracted, including 249 bacterial and two archaeal genomes from sequencing data of 30 metagenomic sequencing samples comprising 15 air and 15 manure samples collected from 15-layer farms. Interestingly 22 bacterial MAGs were not classified to species levels using GTDB-based classification. ARGs were mainly harbored by the genera Staphylococcus, Alistepes, Romboutsia, and Enterococcus. Bacteroides is a main taxon carrying ARGs in air samples. Ammonia production-related genes were mainly tracked in Staphylococcus, Ruminococcus and Corynebacterium genera. The assimilatory sulfate reduction genes responsible for sulfur metabolism and hydrogenase-related genes responsible for hydrogen cycling were traced from Staphylococcus originated from both air and manure. The current study provides characterizations of MAGs from a poultry housing environment by linking microbial taxa with virulence, resistance, and metabolic functions. The findings emphasize the role of microbiota in shaping gas emissions and AMR, with implications for poultry health and worker’s safety and the ultimate aim of sustainable poultry production.