Explore the vast range of titles available.

Infectious bronchitis virus (IBV) infection causes significant economic losses to various sectors of the poultry industry worldwide. Over the past few years, the incidence of false layer syndrome in Eastern Canadian layer flocks has been associated with the increased prevalence of the IBV Delmarva (DMV)/1639 strain. In this study, 1-day-old specific-pathogen-free (SPF) hens were infected with the Canadian DMV/1639 strain and observed until 16 weeks of age in order to determine if the IBV DMV/1639 strain is causing false layer syndrome. Early after infection, the virus showed a wide tissue distribution with characteristic gross and histopathological lesions in the respiratory tract and kidney. Around 60–70% of the infected hens demonstrated continuous cloacal viral shedding until the end of the experiment (at 16 weeks) which was associated with high IBV genome loads detected in the cecal tonsils. The experiment confirmed the field observations that the Canadian DMV/1639 strain is highly pathogenic to the female reproductive tract causing marked cystic lesions in the oviduct. Moreover, significant histopathological damage was observed in the ovary. Our study provides a detailed description of the pathological consequences of the IBV DMV/1639 strain circulating in an important poultry production sector.

Background Avian infectious bronchitis (IB) is a highly contagious respiratory disease that affects the poultry industry globally. The disease is caused by avian infectious bronchitis virus (IBV), member of the genus Gammacoronavirus . In Ethiopia, IBV has been reported in both commercial and backyard chickens based on clinical observation. The objectives of this study were to isolate the virus, conduct molecular based identification, and phylogenetic analysis of the circulating IBV isolates. Methods and materials A cross-sectional study was conducted between November 2023 and May 2024 in Mekele and Bishoftu, Ethiopia. A total of 49 clinical samples were collected, comprising 12 tissue samples and 39 pooled swab samples. Of these, 6 samples—specifically, 5 swab samples and 1 tissue sample—tested positive for infectious bronchitis virus (IBV) through virus-specific conventional RT-PCR and real-time PCR. Nested PCR was performed using serotype-specific primers. The purified PCR products, which targeted the spike glycoprotein S1 subunit gene and the 3′ UTR of the IBV, were sequenced, followed by phylogenetic tree analysis. Results The six positive samples propagated into specific pathogen free embryonated eggs and exhibited characteristic IBV lesions and mortality observed over five consecutive passages. IBV isolates from Bishoftu ( n  = 4) and Mekele ( n  = 2) were amplified using one-step RT-PCR to target 466 bp of the S1 subunit gene and 433 bp of the 3ʹUTR. A BLAST search on the S1 partial gene and 3ʹUTR sequences, nested PCR, and phylogenetic analysis revealed that the present IBV isolates are genetically similar to the Massachusetts serotype. The S1 gene sequences of the five IBV isolates were deposited in GenBank with accession numbers PQ389500 to PQ389504. Conclusions This is the first detailed study on IB virus isolation, molecular detection, sequencing, and phylogenetic analysis in Ethiopia. The findings revealed that the outbreaks were caused by the IB virus, which created a serious health risk and economic losses in the chicken industry. To the author’s knowledge, this is the first comprehensive study on the isolation and genetic analysis of IBV in Ethiopia. Further research on the economic impact of IBV in chicken production, farm biosecurity, serotyping of circulating IB virus, and vaccine development based on the local serotypes is recommended.

Gammacoronavirus infectious bronchitis virus (IBV) causes a highly contagious disease in chickens and seriously endangers the poultry industry. The emergence and co-circulation of diverse IBV serotypes and genotypes with distinct pathogenicity worldwide pose a serious challenge to the development of effective intervention measures. In this study, we report the epidemic trends of IBV in China from 2019 to 2023 and a comparative analysis on the antigenic characteristics and pathogenicity of isolates among major prevalent lineages. Phylogenetic and recombination analyses based on the nucleotide sequences of the spike (S) 1 gene clustered a total of 205 isolates into twelve distinct lineages, with GI-19 as a predominant lineage (61.77 ± 4.56%) exhibiting an overall increasing trend over the past five years, and demonstrated that a majority of the variants were derived from gene recombination events. Further characterization of the growth and pathogenic properties of six representative isolates from different lineages classified four out of the six isolates as nephropathogenic types with mortality rates in one-day-old SPF chickens varying from 20–60%, one as a respiratory type with weak virulence, and one as a naturally occurring avirulent strain. Taken together, our findings illuminate the epidemic trends, prevalence, recombination, and pathogenicity of current IBV strains in China, providing key information for further strengthening the surveillance and pathogenicity studies of IBV.

•An inactivated IBV vaccine encapsulated in chitosan nanoparticles (IBV-CS) was developed.•Immunogenicity of IBV-CS vaccine was evaluated by mucosal route vaccination.•IBV-CS vaccine induced high antibody and CMI responses at mucosal sites.•IBV-CS vaccine provided an effective protection against IBV infection. Avian infectious bronchitis virus (IBV) is one of the most important viral diseases of poultry. The mucosa of upper respiratory tract, specially the trachea, is the primary replication site for this virus. However, conventional inactivate IBV vaccines usually elicit reduced mucosal immune responses and local protection. Thus, an inactivated IBV vaccine containing BR-I genotype strain encapsulated in chitosan nanoparticles (IBV-CS) was produced by ionic gelation method to be administered by oculo-nasal route to chickens. IBV-CS vaccine administered alone resulted in markedly mucosal immune responses, characterized by high levels of anti-IBV IgA isotype antibodies and IFNγ gene expression at 1dpi. The association of live attenuated Massachusetts IBV and IBV-CS vaccine also induced strong mucosal immune responses, though a switch from IgA isotype to IgG was observed, and IFNγ gene expression peak was late (at 5 dpi). Efficacy of IBV-CS was evaluated by tracheal ciliostasis analysis, histopathology examination, and viral load determination in the trachea and kidney. The results indicated that IBV-CS vaccine administered alone or associated with a live attenuated heterologous vaccine induced both humoral and cell-mediated immune responses at the primary site of viral replication, and provided an effective protection against IBV infection at local (trachea) and systemic (kidney) sites.

The continuous emergence of avian infectious bronchitis virus (IBV) variants poses a critical threat to poultry health and productivity in China. In this study, we conducted comprehensive genetic and antigenic analyses of IBV strains isolated in our laboratory between 2020 and 2024. A total of 94 IBV isolates were sequenced for the S1 gene, revealing widespread nucleotide insertions, deletions, and mutations. Phylogenetic analysis indicated that GI-19 was the predominant genotype (70.21%), followed by GI-13 (21.28%). Recombination analysis using RDP 5.42 identified 14 recombinant strains, primarily GI-13/GI-22 (50%), GI-19/GI-7 (28.6%), and GI-19/GI-22 (21.4%), which were further confirmed using Simplot. Glycosylation analysis revealed that all isolates possessed 14 to18 N-glycosylation sites, whereas only the SDJN3/23 strain contained an O-glycosylation site (position 416). Novel cleavage site motifs (HRRKR, HRHRR, RRFRR) were identified in GI-19 strains, diverging from the canonical HRRRR. The evolutionary rate calculated via BEAST software, was 1.98 × 10 -4 substitutions/site/year. Serum neutralization assays demonstrated that GI-19 recombinants exhibited partial one-way cross-protection against GI-1, GI-13, and GI-22 genotypes (titer ≥ 1:32), but reciprocal neutralization was limited. Overall, we systematically characterized the genetic diversity and antigenic evolution of the currently circulating IBV strains in China, emphasizing the critical demand for genotype-specific vaccine development and dynamic surveillance systems to counteract viral immune escape.

Avian infectious bronchitis virus (IBV) is a highly transmissible virus that causes respiratory, reproductive, and renal syndromes, resulting in significant economic losses for the global poultry industry. This study aimed to evaluate the application of high-resolution melting analysis (HRM) as a novel, efficient, and cost-effective tool for the rapid diagnosis and genotyping of Egyptian IBV strains. The investigation focused on the N gene and the 3’ untranslated region (3’ UTR). HRM curves were generated from 435 bp PCR products obtained from 22 IBV-positive avian samples. The purified PCR products, which amplified the 3’ UTR, were sequenced and subsequently compared with analogous S1 gene sequences to differentiate between vaccine strains and field strains, specifically the Egyptian strain 4/91 (GI-13), variant II (GI-23), and the classic strain (GI-1). The high-resolution melting curve analysis (HRM) successfully distinguished vaccine reference strains (Ma5, IB-Primer, 4/91, and Variant II), while the IBV field strains were categorized into three distinct pattern clusters based on the similarity of their melting curves, which were confirmed by S1 gene sequences. Both strains 4/91 and variant II exhibited a deletion of about 15 nucleotides at the terminus of the N-gene compared to classic strains. Closed-tube PCR combined with HRM-curve analysis provides a fast and reliable technique for genotyping IBV strains, including IBV vaccine strains and IBV field strains.

Avian coronavirus, also known as infectious bronchitis virus (IBV), is the causative agent of infectious bronchitis (IB). The non-structural proteins (NSPs) of IBV are critical for viral replication and for evading the host’s immune response. The innate immune response serves as the first line of defense against viral infections. The IBV genome codes for 15 NSPs (NSP2-16). In this study, we identified host proteins interacting with IBV NSP10 using co-immunoprecipitation (Co-IP) and liquid chromatography-tandem mass spectrometry (LC/MS/MS). Proteomic analysis revealed that interactions of host proteins with NSP10 are involved in processes such as localization, transport, and metabolism, regulation of the cell cycle, and antiviral responses. We further explored the role of NSP10 in these immune and cellular regulation pathways and also confirmed the interaction between NSP10 and the host protein hnRNPA1. Further investigation showed that hnRNPA1 inhibited IBV replication. It is speculated that the binding of hnRNP A1 to NSP10 interferes with the function of the replication complex, thereby inhibiting virus replication. However, co-overexpression of NSP10 and hnRNP A1 partially restored viral replication, suggesting a complex relationship between these two proteins. These findings demonstrate that IBV NSP10 plays a significant role in viral infection and in modulating host cell processes, highlighting its potential as a target for therapeutic interventions.

Infectious bronchitis (IB) is an acute contagious disease of poultry caused by infectious bronchitis virus (IBV). This study investigated the immunopathogenesis and tissue tropism of an Indian IBV field isolate (IBV/Chicken/India/IVRI/Rajasthan/01/2023) in experimental broiler chickens. This isolate belongs to the G1-1 lineage and is closely associated with the Mass genotype. 106.23 EID50/0.2 mL of the virus was administered intranasally and intraocularly to the IBV-challenge group, whereas uninoculated allantoic fluid was administered to the control group. Clinical signs, gross and histopathological lesions, immunohistochemistry (IHC), viral load, humoral responses, and the relative expression of immune response genes were evaluated at seven observation points. The infected group showed a significant reduction in weight gain from 3 dpi onwards, with clinical signs of varying severity from 3 to − 11 dpi. Gross lesions and microscopic changes were observed in the nasal turbinates, trachea, lungs, and kidneys, mainly representing epithelial degeneration and necrosis with mononuclear infiltrates. The caecal tonsils also showed microscopic lesions at 7–9 dpi. Absolute viral load estimation in the organs corroborated the lesion severity scores and IHC results. The expression of innate immune responses broadly demonstrated higher expression in the trachea and lungs of the IBV-infected group during the early phase of infection, whereas similar responses were observed in the kidneys and caecal tonsils during the later phases of infection. This study suggests that the given IBV isolate may cause significant production losses in broilers and exhibit tissue tropism for both respiratory and non-respiratory tissues, triggering varying innate and adaptive immune responses.

Avian influenza virus (AIV) variants emerge frequently, which challenges rapid diagnosis. Appropriate diagnosis reaching the sub- and pathotype level is the basis of combatting notifiable AIV infections. Real-time RT-PCR (RT-qPCR) has become a standard diagnostic tool. Here, a total of 24 arrayed RT-qPCRs is introduced for full subtyping of 16 hemagglutinin and nine neuraminidase subtypes of AIV. This array, designated Riems Influenza A Typing Array version 2 (RITA-2), represents an updated and economized version of the RITA-1 array previously published by Hoffmann et al. RITA-2 provides improved integration of assays (24 instead of 32 parallel reactions) and reduced assay volume (12.5 µL). The technique also adds RT-qPCRs to detect Newcastle Disease (NDV) and Infectious Bronchitis viruses (IBV). In addition, it maximizes inclusivity (all sequences within one subtype) and exclusivity (no intersubtypic cross-reactions) as shown in validation runs using a panel of 428 AIV reference isolates, 15 reference samples each of NDV and IBV, and 122 clinical samples. The open format of RITA-2 is particularly tailored to subtyping influenza A virus of avian hosts and Eurasian geographic origin. Decoupling and re-arranging selected RT-qPCRs to detect specific AIV variants causing epizootic outbreaks with a temporal and/or geographic restriction is possible.

Infectious bronchitis virus (IBV) presents a major threat to global poultry production, necessitating a thorough understanding of its evolutionary relationships for effective control measures. This study presents a novel distance-based Minimum Span Clustering (MSClustering) method to cluster 311 IBV strains, with a comparison of its results to the established IBV classification. Phylogenetic network and recombination analyses were employed to investigate IBV evolutionary relationships and transmission pathways. The phylogenetic network revealed distinct clusters reflecting relationships between IBV strains. Importantly, these network patterns, combined with recombination event analysis, suggest an unrecognized role for migratory birds in IBV dissemination, highlighting potential transmission pathways beyond established poultry trade routes. These findings contribute to advancing our understanding of IBV evolution and support the development of targeted strategies for controlling viral outbreaks in poultry populations. While statistical limitations may affect threshold estimation for smaller networks, our MSClustering method significantly accelerates processing speeds-approximately 100,000 times faster than PhyML when analyzing the dataset-enabling comprehensive-scale phylogenetic analysis of viruses.