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From 2014–2023, infectious bronchitis virus (IBV) was detected in 6,589 samples from Canada, and partial nucleotide (nt) sequences of the IBV spike protein (S) gene were determined for 1,678 samples. Based on their S gene nt sequence identities and origin, Canadian IBVs could be classified into 4 groups: 1) 50.3% were variant viruses related to strains described in the United States; 2) 45.6% were vaccine-like viruses; 3) 2.1% were Eurasian viruses; 4) 2.0% were Canadian variants. Outbreaks with IBVs related to strains CAL1734/04, 4/91, and DMV/1639/11 were often associated with more severe disease in all chicken commodity groups. With the emergence of numerous IBV strains, the severity of infection and number of affected flocks increased. Outbreaks with various IBV strains overlapped in their emergence, peaked, and regressed, but the introduction of DMV/1639/11 has resulted in a continuous field challenge since its first detection in 2015. [ABSTRACT FROM AUTHOR]

Two vaccination-challenge trials were performed using a commercial infectious bronchitis virus (IBV) BR1 vaccine, given alone or combined with a commercial IBV Mass vaccine against challenges with IBV M41, 793B, D388 (QX), Q1, Brasil-1 or Variant 2 challenge viruses, which includes the IB viruses that are dominant in South America. The efficacy of the vaccines against the challenge viruses was investigated by determination of the ciliary activity of the tracheal epithelium after challenge. The level of protection induced by the IBV BR1 vaccine alone against the six IBV challenge strains, of which five were of heterologous genotypes, varied from 50% to 100% with an average of 80%. The level of protection induced by the combination of the IBV BR1 and IBV Mass vaccines against the six IBV challenge strains, of which four were of heterologous genotypes, varied from 80% to 100% with an average of 92%. Vaccination with IBV BR1 alone provided a high level of protection against most tested challenge viruses, though the combination of IBV BR1 and IBV Mass was more consistent, showing less variation and compliance with the criterium mentioned in the European Pharmacopoeia 10th edition (at least 80% protection) for all tested challenge viruses. These trials show that vaccination with a combination of IBV BR1 and IBV Mass vaccines provides high levels of protection against the circulating IBV strains in South America. [ABSTRACT FROM AUTHOR]

Infectious bronchitis in birds, caused by a coronavirus, is a highly contagious viral disease that causes economic losses in the poultry industry worldwide. It affects the respiratory, urinary, and genital tracts, and control and prevention are focused on vaccination and biosecurity measures. This study compares histopathological lesions caused by IB88, H120, and IB4-91 vaccines in broiler chickens aged 1 to 5 days. One hundred Ross 308 chickens were divided into four groups: group 1 received the IB4-91 vaccine, group 2 was administered the H120 vaccine, group 3 received the IB88 vaccine, and group 4 served as the control group. Over a period of five days, starting from the second day, five chickens from each group were randomly selected and euthanized. Histopathological samples were collected from the trachea, lungs, and kidneys, processed into slides, and examined under an optical microscope for comparative analysis. When comparing the control and vaccinated groups, there were significant differences regarding histopathological indicators. These included hyperemia and infiltration of inflammatory cells in the kidney, lung hyperemia, infiltration of inflammatory cells, necrosis of respiratory epithelium, and hyperplasia of tracheal mucous cells. Differences were noted between the IB4-91 and H120 groups regarding inflammatory cell infiltration, respiratory epithelium necrosis, tracheal mucous cell hyperplasia, and renal hyperemia. Similarly, variations were observed between the IB88 and H120 groups regarding respiratory epithelium necrosis and tracheal inflammatory cell infiltration. Furthermore, differences were identified in tracheal mucosal hyperplasia and renal hyperemia between the IB4-91 and IB88 groups. These findings highlight distinct histopathological responses induced by different vaccines in broiler chickens and emphasize the importance of vaccine selection in poultry health management. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) strains of genotype GVIII have been emerging in Europe in the last decade, but no biological characterization has been reported so far. This paper reports the extensive genetic and biological characterization of IBV strain D2860 of genotype GVIII which was isolated from a Dutch layer flock that showed a drop in egg production. Whole genome sequencing showed that it has a high similarity (95%) to CK/DE/IB80/2016 (commonly known as IB80). Cross-neutralization tests with antigens and serotype-specific antisera of a panel of different non-GVIII genotypes consistently gave less than 2% antigenic cross-relationship with D2860. Five experiments using specified pathogen-free chickens of 0, 4, 29 and 63 weeks of age showed that D2860 was not able to cause clinical signs, drop in egg production, false layers or renal pathology. There was also a distinct lack of ciliostasis at both 5 and 8 days post-inoculation at any age, despite proof of infection by immunohistochemical (IHC) staining, RT–PCR and serology. IHC showed immunostaining between 5 and 8 days post inoculation in epithelial cells of sinuses and conchae, while only a few birds displayed immunostaining in the trachea. In vitro comparison of replication of D2860 and M41 in chicken embryo kidney cells at 37°C and at 41°C indicated that D2860 might have a degree of temperature sensitivity that might cause it to prefer the colder parts of the respiratory tract. [ABSTRACT FROM AUTHOR]

With the emergence of new variant strains resulting from high mutation rates and genome recombination, avian infectious bronchitis virus (IBV) has caused significant economic losses to the poultry industry worldwide. Little is known about the underlying mechanisms of IBV-host interactions, particularly how IBV utilizes host metabolic pathways for efficient viral replication and transmission. In the present study, the effects of the cell membrane, viral envelope membrane, and viperin-mediated cholesterol synthesis on IBV replication were explored. Our results revealed significant increase in cholesterol levels and the expression of viperin after IBV infection. Acute cholesterol depletion in the cell membrane and viral envelope membrane by treating cells with methyl-β-cyclodextrin (MβCD) obviously inhibited IBV replication; thereafter, replenishment of the cell membrane with cholesterol successfully restored viral replication, and direct addition of exogenous cholesterol to the cell membrane significantly promoted IBV infection during the early stages of infection. In addition, overexpression of viperin effectively suppressed cholesterol synthesis, as well as IBV replication, whereas knockdown of viperin (gene silencing with siRNA targeting viperin, siViperin) significantly increased IBV replication and cholesterol levels, whereas supplementation with exogenous cholesterol to viperin-transfected cells markedly restored viral replication. In conclusion, the increase in viperin induced by IBV infection plays an important role in IBV replication by affecting cholesterol production, providing a theoretical basis for understanding the pathogenesis of IBV and discovering new potential antiviral targets. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) is a significant threat to poultry worldwide, but its status in Ethiopia remains understudied. Thus, this study aimed to detect the virus and associated risk factors in South West Ethiopia. Ninety oropharyngeal swab samples were purposively collected from symptomatic chickens located in Jimma town, Seqa Chekorsa, and Tiro Afeta woredas of the Jimma zone between November 2021 and April 2022 to detect IBV virus by using RT‐PCR. A side‐by‐side questionnaire was administered to assess risk factors. Total RNA was extracted, reverse transcription polymerase chain reaction (RT‐PCR) was conducted, and products were visualized under UV light. The overall proportion of IBV was 16.6% (15/90). No statistical association was observed between any of the animal risk factors and the detection of the virus (P = 0.57, 0.586, and 1). However, the proportion of birds infected by the virus was higher in males, exotic breeds, and adults compared to females, local breeds, and young birds. Similarly, none of the management risk factors had a significantly different effect on virus detection (P = 0.25, 0.09, 0.088, and 0.726). However, improper carcass disposal (OR = 0.43, 95% CI: 0.13–1.4), lack of veterinary services (OR = 2.7, 95% CI: 0.8–8.3), and the presence of wild birds/rodents (OR = 4.4, 95% CI: 0.88‐22.3) were associated with increased IBV risk but not cleaning of feeders/drinkers (OR = 1.1, 95% CI: 0.2–4.8). These findings underscore the need for enhanced biosecurity practices and further research to implement informed IBV control strategies in Ethiopia. [ABSTRACT FROM AUTHOR]

Infectious Bronchitis Virus (IBV) is a major threat to the poultry industry worldwide, causing significant economic losses. While the virus's genetic structure is well understood, the specific strains circulating in Bolivia have remained uncharacterized until now. This study aimed to identify and characterize new IBV strains in Bolivia. Tissue samples from broilers exhibiting clinical signs of Infectious Bronchitis were screened to detect IBV using real-time RT-PCR (RT-qPCR). Positive samples with low cycle threshold (Ct) values were selected for sequencing the full S1 gene. Of the 12 samples analyzed, 10 were determined to be positive for IBV. However, only four samples yielded sufficient genetic material for sequencing and subsequent phylogenetic analysis. The results revealed the presence of GI-1 and GI-23 lineages, both belonging to genotype I (GI). The GI-1 lineage showed >99% sequence identity to the H120 and Massachusetts vaccine strains, suggesting a close relationship. In contrast, the GI-23 lineage clustered with other IBV strains, showing a distinct subclade that is genetically distant from Brazilian strains. No evidence of recombination was found. Furthermore, amino acid substitution analysis identified specific mutations in the S1 subunit, particularly in the hypervariable regions 1, 2, and 3. These mutations could potentially alter the virus's antigenicity, leading to reduced vaccine efficacy. The findings of this study highlight the importance of continued and broad genomic surveillance of circulating IBV strains and the need to improve vaccination strategies in Bolivia. [ABSTRACT FROM AUTHOR]

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Copyright of Avian Diseases is the property of American Association of Avian Pathologists, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Infectious bronchitis virus (IBV) is the first coronavirus discovered in the world in the early 1930s and despite decades of extensive immunoprophylaxis efforts, it remains a major health concern to poultry producers worldwide. Rapid evolution due to large poultry population sizes coupled with high mutation and recombination events and the reliance of the antiviral immune response on specific antibodies against the epitopes of the S1 glycoprotein, render the control of IBV extremely challenging. The numerous and rapidly evolving genetic and antigenic IBV types are currently classified based on the whole S1 gene sequence, into 36 lineages clustered in eight genotypes. Most lineages (29) are grouped in genotype I (GI). “Variant 2” (Israel/Variant 2/1998) is the prototype strain of lineage GI-23 and, since this lineage emerged during the mid-1990s in the Middle East, it has evolved into numerous genetically related strains and disseminated to five continents. The hallmarks of IBV Variant 2-like strain infections are high virulence and remarkable nephrotropism and nephropathogenicity; however, the molecular mechanisms of these traits remain to be elucidated. Limited protection from previously utilized vaccine strains and accumulated losses to poultry producers have urged the development and implementation of homologous Variant 2-like vaccine strains. The latest avian coronavirus biology with specific emphasis on the cumulative knowledge about IBV “Variant 2” and emergence of related strains, characteristics and control are reviewed. [ABSTRACT FROM AUTHOR]

Avian leukemia virus (ALV) is one of the main pathogens of poultry tumor diseases, and has caused significant economic losses to the poultry industry since its discovery. Therefore, establishing a rapid detection method is essential to effectively prevent and control the spread of ALV. In this study, specific CRISPR RNA (crRNA) and recombinase-aided amplification (RAA) primers with T7 promoter were designed based on the relatively conserved sequence of avian leukemia virus. When crRNA recognized the target sequence, Cas13a protein was activated to cut the reporting probes, and then the detection results were read by using lateral flow dipstick (LFD). The RAA-CRISPR/Cas13a-LFD reaction system was constructed. The RAA amplification time, Cas13a protein concentration, crRNA concentration and CRISPR reaction time were optimized to evaluate the specificity, sensitivity and reproducibility of the system. Finally, RAA-CRISPR/Cas13a-LFD method was compared with Polymerase chain reaction (PCR)-Agarose electrophoresis method and qPCR method in the detection of clinical samples, and the reliability of RAA-CRISPR/Cas13a-LFD method was evaluated. The results showed that the RAA-CRISPR/Cas13a-LFD method could effectively amplify the target gene at 37°C for 40 min, and the test results could be determined by LFD visual observation. The method had good specificity and no cross-reaction with Marek's disease virus (MDV), Fowl adenovirus (FAdV), Infectious bursal disease virus (IBDV), Newcastle disease virus (NDV), Infectious laryngotracheitis virus (ILTV), and Infectious bronchitis virus (IBV). The minimum detection limit of the method was 100 copies/μL, and it had good repeatability and stability. The coincidence rate of clinical detection reached 97.69% and 99.23%. In summary, this study established a simple, efficient, accurate and visualized ALV detection method, which can be used for the prevention and rapid clinical diagnosis of avian leukosis (AL). [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) is responsible for avian infectious bronchitis, a disease prevalent in countries with intensive poultry farming practices. Given the presence of multiple genotypic strains in China, identifying the regionally dominant genotypes is crucial for the implementation of effective prevention and control measures. This study focuses on the IBV strain CK/CH/WJ/215, isolated from a diseased commercial chicken flock in China in 2021. The CK/CH/WJ/215 isolate was genetically characterized through complete S1 sequence analysis. Phylogenetic comparisons were made with prevalent vaccine strains (H120, LDT3-A, and 4/91). Glycosylation patterns in the S1 protein were also analyzed. Pathogenicity was assessed in 7-day-old specific-pathogen-free chicks, monitoring morbidity, mortality, and tissue tropisms. Phylogenetic analysis clustered the CK/CH/WJ/215 isolate within the GI-19 lineage. Identity with the vaccination strains H120, LDT3-A, and 4/91 was low (75.7%, 78.6%, and 77.5% respectively). Novel glycosylation sites at positions 138 and 530 were identified compared to H120 and LDT-A. The isolate demonstrated nephropathogenic characteristics, causing 100% morbidity and 73.3% mortality in SPF chicks, with broader tropisms in tissues including trachea, lungs, kidneys, and bursa of Fabricius. Comprehensive genetic and pathological investigations revealed significant differences between the CK/CH/WJ/215 isolate and common vaccine strains, including novel glycosylation sites and a strong multiorgan infective capability. These findings are crucial for understanding the evolutionary dynamics of IBV and developing more effective prevention and control strategies. [ABSTRACT FROM AUTHOR]

Newcastle Disease (ND) and Infectious Bronchitis (IB) are two significant diseases that pose threats to the poultry industry, caused by Newcastle disease virus (NDV) and Infectious bronchitis virus (IBV), respectively. Currently, the control and prevention of these diseases primarily rely on vaccination. However, commercial ND and IB vaccines face challenges such as poor cross-protection of inactivated IBV strains and interference from live vaccines when used together, leading to immunization failures. Previously, we reported the successful rescue of a recombinant NDV expressing multiple epitopes of IBV, named rNDV-IBVT/B, which showed promising immunoprotective efficacy against both NDV and IBV. This study focuses on the biosafety of the genetically modified recombinant vaccine candidate rNDV-IBV-T/B. Immunization was performed on day-old chicks, ducklings, goslings, and ICR mice. Observations were recorded on clinical symptoms, body weight changes, and post-mortem examination of organs, as well as histopathological preparations of tissue samples. The results indicated that the rNDV-IBV-T/B vaccine candidate had no adverse effects on the growth of targeted animals (chickens) and non-target species (ducks, geese) as well as in mammals (mice). Additionally, histopathological slides confirmed that the vaccine is safe for all tested species. Further studies evaluated the potential of rNDV-IBV-T/B to spread horizontally and vertically post-immunization, and its environmental safety. The findings revealed that the vaccine candidate lacks the capability for both horizontal and vertical transmission and does not survive in the environment. In conclusion, the rNDV-IBV-T/B strain is safe and holds potential as a new chimeric live vaccine for ND and IB. [ABSTRACT FROM AUTHOR]

NIBV is an acute and highly contagious virus that has a major impact on the poultry industry. Wogonin, as a flavonoid drug, has antiviral effects, but there have been no reports indicating its role in renal injury caused by NIBV infection. The aim of this study is to investigate the antiviral effect of wogonin against NIBV. Renal tubular epithelial cells were isolated and cultured, and divided into four groups: Con, Con+Wog, NIBV and NIBV+Wog. We found that wogonin significantly inhibited the copy number of NIBV and significantly alleviated NIBV-induced cell apoptosis and necrosis. Moreover, wogonin inhibited the reduction in mitochondrial membrane potential and the aberrant opening of mPTP caused by NIBV. In conclusion, wogonin can protect renal tubular epithelial cells from damage by inhibiting the replication of NIBV and preventing mitochondrial apoptosis and necroptosis induced by NIBV. [ABSTRACT FROM AUTHOR]

Coronaviruses constitute a global threat to human and animal health. It is essential to investigate the long-distance RNA-RNA interactions that approximate remote regulatory elements in strategies, including genome circularization, discontinuous transcription, and transcriptional enhancers, aimed at the rapid replication of their large genomes, pathogenicity, and immune evasion. Based on the primary sequences and modeled RNA-RNA interactions of two experimentally defined coronaviral enhancers, we detected via an in silico primary and secondary structural analysis potential enhancers in various coronaviruses, from the phylogenetically ancient avian infectious bronchitis virus (IBV) to the recently emerged SARS-CoV-2. These potential enhancers possess a core duplex-forming region that could transition between closed and open states, as molecular switches directed by viral or host factors. The duplex open state would pair with remote sequences in the viral genome and modulate the expression of downstream crucial genes involved in viral replication and host immune evasion. Consistently, variations in the predicted IBV enhancer region or its distant targets coincide with cases of viral attenuation, possibly driven by decreased open reading frame (ORF)3a immune evasion protein expression. If validated experimentally, the annotated enhancer sequences could inform structural prediction tools and antiviral interventions. [ABSTRACT FROM AUTHOR]

Respiratory RNA viruses such as Infectious bronchitis virus (IBV) and Avian metapneumovirus (aMPV), which are characterized by generating both respiratory damage and adverse effects on reproductive organs, affect poultry production economically due to high mortality rate and decrease in egg production and quality. Particularly, aMPV has three genotypes that have been reported with greater frequency in chickens: aMPV-A, aMPV-B, and aMPV-C. The present study proposes the design of a multiplex RT-qPCR assay for the simultaneous diagnosis of the 3 genotypes of interest of aMPV and IBV, followed by testing of 200 tracheal samples of vaccinated chickens with respiratory symptoms and finally a phylogenetic analysis of the sequences found. The assay detected up to 1 copy of each viral genome. The standard curves showed an efficiency between 90 and 100% in the multiplex assay and inter- and intra-assay coefficients of variation of 0.363 and 0.459, respectively and inter- and intraassay coefficients of variation of 0.363 and 0.459, respectively. 69.5% of samples were found positive alone or in coinfection. 114 samples were positive for IBV, 13 for aMPV-A and 25 for aMPV-B. RNA of aMPV-C was no detected. The most commonly found combination was aMPV-B and IBV within 6 samples, and the least common was aMPV-A and aMPV-B in coinfection in 2 samples. The assay was specific for amplification of the genomes of the studied respiratory viruses (IBV, aMPV-A, aMPV-B, aMPV-C) as no amplification was shown from other viral genomes (ChPV, CAstV, ANV, and FAdV) or from the negative controls. Partial genomic Sanger sequencing enabled to identify circulating vaccine-derived and wild-type strains of IBV and vaccine and vaccine-derived strains of aMPV-B. In conclusion, this newly developed multiplex RT-qPCR was shown to be able to detect individual infections as well as co-infections among the respiratory viruses investigated. It was demonstrated to be a reliable and efficient tool for rapidly and safely diagnosing these infections. Furthermore, this study represents the first report of aMPV strains in Ecuadorian poultry and demonstrates the circulation of aMPV-A, aMPV-B, and GI-13 IBV strains in unvaccinated chicken populations in the country. Thus, it highlights the importance of simultaneously identifying these pathogens in greater detail and on a regular basis in Ecuador. [ABSTRACT FROM AUTHOR]

Like all coronaviruses, infectious bronchitis virus, the causative agent of infectious bronchitis in chickens, exhibits a high mutation rate. Adaptive mutations that arise during the production of live attenuated vaccines against IBV often decrease virulence. The specific impact of these mutations on viral pathogenicity, however, has not been fully elucidated. In this study, we identified a mutation at the 3' end of the S gene in an IBV strain that was serially passaged in chicken embryos, and showed that this mutation resulted in a 9-aa truncation of the cytoplasmic tail (CT) of the S protein. This phenomenon of CT truncation has previously been observed in the production of attenuated vaccines against other coronaviruses such as the porcine epidemic diarrhea virus. We next discovered that the 9-aa truncation in the S protein CT resulted in the loss of the endoplasmic-reticulum-retention signal (KKSV). Rescue experiments with recombinant viruses confirmed that the deletion of the KKSV motif impaired the localization of the S protein to the endoplasmic-reticulum-Golgi intermediate compartment (ERGIC) and increased its expression on the cell surface. This significantly reduced the incorporation of the S protein into viral particles, impaired early subgenomic RNA and protein synthesis, and ultimately reduced viral invasion efficiency in CEK cells. In vivo experiments in chickens confirmed the reduced pathogenicity of the mutant IBV strains. Additionally, we showed that the adaptive mutation altered the TRS-B of ORF3 and impacted the transcriptional regulation of this gene. Our findings underscore the significance of this adaptive mutation in the attenuation of IBV infection and provide a novel strategy for the development of live attenuated IBV vaccines. Author summary: The administration of live attenuated vaccines is currently recognized as the most effective strategy for preventing infections caused by IBV. Understanding how mutations arising during vaccine production influence IBV virulence is crucial for developing more effective vaccines. In this study, we focused on a specific mutation in the S gene of IBV, which arose during viral propagation in chicken embryos. This mutation resulted in the truncation of the CT region of the S protein and concurrently eliminated a critical motif required for the retention of the protein at the viral assembly site. Similar S protein truncation has been observed in the production of attenuated vaccines against other coronaviruses, suggesting that the mutation identified in IBV in the present study was an adaptive mutation driven by natural selection pressure. Our findings underscore the value of targeting this adaptive mutation site as a strategy for reducing IBV virulence, and for the development of effective live attenuated vaccines against IBV and other coronaviruses. [ABSTRACT FROM AUTHOR]

The recent Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic highlights the significant threat coronaviruses (CoVs) pose to public health. With their extensive cross-continental movements, migratory birds have the potential to serve as reservoirs and vectors for CoVs. This study aimed to investigate the prevalence of CoVs in birds in densely populated areas of Guangdong Province, China. Of the 128 samples collected from birds, six tested positive for CoVs (4.7%, 95% CI: 1.7–9.9%), and three complete viral genomes were obtained through viral metagenomics and PCR. Phylogenetic analysis revealed that two CoVs (MD_XN18 and SG_DWY40) belonged to the Gammacoronavirus genus, while one (CP_XN11) belonged to the Deltacoronavirus genus. Homology analysis revealed that the MD_XN18 strain discovered in mallards shares 95.6–97.4% sequence similarity with chicken infectious bronchitis viruses (IBVs), providing direct evidence that migratory mallards can transmit avian IBVs. Recombination analysis suggested that two genomic regions of SG_DWY40 could originate from unknown sources through recombination, potentially leading to the expression of a novel viral protein, provisionally named NS3.5. These findings underscore the ongoing transmission and evolution of CoVs among birds in cities near Guangdong Province, emphasizing the need for continued monitoring and research. [ABSTRACT FROM AUTHOR]

Avian infectious bronchitis is an acute respiratory disease of poultry of particular concern for global food security. Investigation of infectious bronchitis virus (IBV), the causative agent of avian infectious bronchitis, via reverse genetics enables deeper understanding of virus biology and a rapid response to emerging variants. Classic methods of reverse genetics for IBV can be time consuming, rely on recombination for the introduction of mutations, and, depending on the system, can be subject to genome instability and unreliable success rates. In this study, we have applied data-optimized Golden Gate Assembly design to create a rapidly executable, flexible, and faithful reverse genetics system for IBV. The IBV genome was divided into 12 fragments at high-fidelity fusion site breakpoints. All fragments were synthetically produced and propagated in E. coli plasmids, amenable to standard molecular biology techniques for DNA manipulation. The assembly can be carried out in a single reaction, with the products used directly in subsequent viral rescue steps. We demonstrate the use of this system for generation of point mutants and gene replacements. This Golden Gate Assembly-based reverse genetics system will enable rapid response to emerging variants of IBV, particularly important to vaccine development for controlling spread within poultry populations. [ABSTRACT FROM AUTHOR]

SummaryEffective control of infectious bronchitis is a challenge in commercial poultry operations due to the high transmissibility of the virus. Although multiple IBV lineages are circulating in the United States, the DMV1639-type IBV strain (GI-17) is currently the major circulating variant, creating production losses in the poultry industry. This study aimed to test whether the combination of a GA08 (GI-27) and a Mass-type (GI-1) IB vaccines could significantly reduce the transmission of a DMV1639-type (GI-17) field IBV strain in 4-week-old commercial broilers. Half of them were directly challenged, whereas the other half of the group mates were put in contact twenty-four hours later. Two replicates of the same study set up, including ten directly challenged and ten contact birds per group, were run. Transmission of the challenge virus was significantly reduced in vaccinates (R=0.0), whereas all unvaccinated birds became infected (R=9.6). Reduced transmission of the DMV1639 IB challenge virus by the combined vaccination program in broiler chickens was also accompanied by clinical protection. This data is important because prevention of IBV transmission by vaccination will result in overall reduced viral replication and consequently in reduced likelihood of genetic changes that can lead to new variants. This is the first published evidence of the successful transmission control of a DMV1639 IBV strain in chickens. [ABSTRACT FROM AUTHOR]

Simple Summary: Avian infectious bronchitis is an important infectious disease that causes heavy losses in the poultry industry. Vaccination is an effective preventive measure, but the ability of infectious bronchitis virus (IBV) to mutate reduces the vaccine's protective effect. Therefore, it is quite important to study the pathogenic mechanism of IBV. In this study, we found that IBV infection leads to ROS accumulation in chicken macrophage HD11 cells. The oxidative stress further induced cell apoptosis mediated by mitochondria-mediated apoptotic signaling. In addition, IBV replication was essential to ROS accumulation, and IBV proliferation decreased when ROS activation was blocked. IBV nucleocapsid (N) protein can cause ROS accumulation and cell apoptosis. Our findings may provide insights into the interaction between IBV and its host and uncover the pathogenesis of IBV infection. Infectious bronchitis virus (IBV), a coronavirus that causes severe respiratory and gastrointestinal illness in poultry, leads to substantial economic losses. According to earlier research, IBV infection causes chicken macrophage HD11 cells to undergo cell apoptosis. Reactive oxygen species (ROS) and the IBV-activated intrinsic apoptotic signaling pathway were examined in this work. The findings demonstrate that IBV infection causes ROS to accumulate. Moreover, IBV infection decreased the mitochondrial transmembrane potential in HD11 cells, which could be blocked by ROS antioxidants (PDTC and NAC). The two antioxidants significantly affected the expression of Bcl-2 and Bax and further inhibited the activation of caspase-3 and apoptosis in HD11 cells. Additionally, IBV replication was decreased by blocking ROS accumulation. Pretreating HD11 cells with ammonium chloride (NH4Cl) prevented IBV from entering the cells and reduced the oxidative stress which IBV causes. The ability to accumulate ROS was also lost in UV-inactivated IBV. The IBV N protein induces cell apoptosis through the activation of ROS. These findings provide an explanation for the processes of IBV infection in immune cells by indicating that IBV-induced ROS generation triggers cell apoptosis in HD11 cells. [ABSTRACT FROM AUTHOR]

This study reports the co-existence of two S1 mutants of GI-13 (4/91-like) Infectious Bronchitis Virus (IBV) and Mycoplasma gallisepticum (MG) in a backyard poultry flock that had non-vaccinated 30 broiler chickens and four turkey pullets. Serum samples and tracheal swabs were taken from the chickens and turkey pullets showing respiratory signs. Serum antibody levels were measured using commercial ELISA kits against IBV, Avian Influenza Virus (AIV), Newcastle Disease Virus (NDV), Avian Metapneumovirus (AMPV), MG, Mycoplasma synoviae (MS), and Ornithobacterium rhinotracheale (ORT). Additionally, tracheal swabs were tested for AIV serotypes H5, H7, and H9, NDV, IBV, AMPV, MG, MS, Pasteurella multocida, Avibacterium paragallinarum, and Bordetella avium by circular amplification technology (CAT). Anti-MS, -IBV, -MG, -NDV, -AMPV, and -ORT IgG antibodies were detected in some chicken sera, while anti-NDV, -MG, -MS, and -ORT IgG antibodies were detected in turkey sera. All avian tracheal swabs were positive for MG. However, IBV was only detected in chicken tracheal samples tested by CAT. The IBV strains were genotyped by sequencing a part of the S1 glycoprotein gene. The alignment analyses of two isolates showed 99.35% and 98.69% nucleotide similarities and 99.02% amino acid similarities with the 4/91 IBV vaccine and field strains. Two mutants showed 99.35% nucleotide and 100% amino acid sequence identity to each other. The turkeys and chickens in the flock had MG and MG/IBV co-infections, respectively. Consequently, the presence of mutants of 4/91 (GI-13) IBV genotypes and MG found in backyard poultry could be a potential epidemiological source for commercial flocks in poultry integrations. [ABSTRACT FROM AUTHOR]

This document is an editorial from the International Journal of Molecular Sciences titled "Antiviral Drug Discovery." It highlights the urgent need for antiviral agents, especially in light of the COVID-19 pandemic. The editorial discusses the success of HIV-1 and influenza antivirals in managing these diseases, but also emphasizes the challenges of emerging viruses and drug resistance. The document covers various topics related to antiviral drug discovery, including in silico studies for SARS-CoV-2, new targets for HIV-1, IAV antiviral drugs, and the mechanism of baicalin inhibiting IBV. It also addresses the evaluation of interactions between antivirals and the immune system. The editorial concludes by thanking the authors, reviewers, and journal staff for their contributions. [Extracted from the article]

Infectious bronchitis is a highly contagious viral disease of chickens, causing significant economic losses in Egyptian chicken farms. In this study, we surveyed the prevalence of infectious bronchitis virus infection in broiler chicken flocks in Assiut Governorate as well as description of its pathological lesions. Pooled samples were collected from 22 broiler chicken flocks suspected to be infected with infectious bronchitis virus. Ten samples were confirmed to be positive for infectious bronchitis virus infection using RT-PCR. Nasal discharge, coughing and gasping were the main signs. Grossly, chickens showed hyperemic trachea with a caseous plug at the bifurcation of the trachea. The kidneys appeared congested and enlarged. Trachea, lungs and kidneys specimens were collected for histopathological examination. Tracheal specimens were also collected for electron microscopy study. Microscopically, the trachea showed complete loss of the epithelial cilia, associated with either necrosis or metaplasia of the lining epithelium. The lungs revealed hemorrhagic pneumonia, necrosis of the bronchial epithelium and thickening in interalveolar tissue with inflammatory edema. The kidneys exhibited swollen glomeruli with hypercellularity, necrosis of renal tubules and severe interstitial hemorrhage. Scanning electron microscopy of the trachea revealed severe deciliation, leaving very short microvilli on the mucosal surface. Transmission electron microscopy demonstrated the presence of viral particles in the epithelial lining. So, despite routine vaccination, IBV is still spreading within broiler flocks in Assiut Governorate, causing severe losses and pathological lesions. This requires further investigation of the immune profiling of these broiler chicken flocks. [ABSTRACT FROM AUTHOR]

Viruses have evolved a range of strategies to utilize or manipulate the host’s cellular translational machinery for efficient infection, although the mechanisms by which infectious bronchitis virus (IBV) manipulates the host translation machinery remain unclear. In this study, we firstly demonstrate that IBV infection causes host shutoff, although viral protein synthesis is not affected. We then screened 23 viral proteins, and identified that more than one viral protein is responsible for IBV-induced host shutoff, the inhibitory effects of proteins Nsp15 were particularly pronounced. Ribosome profiling was used to draw the landscape of viral mRNA and cellular genes expression model, and the results showed that IBV mRNAs gradually dominated the cellular mRNA pool, the translation efficiency of the viral mRNAs was lower than the median efficiency (about 1) of cellular mRNAs. In the analysis of viral transcription and translation, higher densities of RNA sequencing (RNA-seq) and ribosome profiling (Ribo-seq) reads were observed for structural proteins and 5′ untranslated regions, which conformed to the typical transcriptional characteristics of nested viruses. Translational halt events and the number of host genes increased significantly after viral infection. The translationally paused genes were enriched in translation, unfolded-protein-related response, and activation of immune response pathways. Immune- and inflammation related mRNAs were inefficiently translated in infected cells, and IBV infection delayed the production of IFN-β and IFN-λ. Our results describe the translational landscape of IBV-infected cells and demonstrate new strategies by which IBV induces host gene shutoff to promote its replication. IMPORTANCE Infectious bronchitis virus (IBV) is a γ-coronavirus that causes huge economic losses to the poultry industry. Understanding how the virus manipulates cellular biological processes to facilitate its replication is critical for controlling viral infections. Here, we used Ribo-seq to determine how IBV infection remodels the host’s biological processes and identified multiple viral proteins involved in host gene shutoff. Immune- and inflammation-related mRNAs were inefficiently translated, the translation halt of unfolded proteins and immune activation-related genes increased significantly, benefitting IBV replication. These data provide new insights into how IBV modulates its host’s antiviral responses. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) causes infectious bronchitis in chicken, an acute, highly contagious respiratory infection. Because of genetic mutations and recombination, IBV forms many subtypes, which makes it difficult to treat the disease and apply commercial vaccines. Therefore, to detect IBV in time and stop the virus from spreading, a novel and convenient IBV detection technology based on reverse transcription recombinase-aided amplification (RT-RAA) was established in this study. According to the S1 gene of IBV CH I–V and Mass genotypes and S1 gene of IBV CH VI genotype, a set of optimal primers were designed and selected to establish a real-time dual fluorescence RT-RAA method. The lowest detection line was 10 copies/μL of RNA molecules and the method exhibited no cross-reactivity with avian reticuloendotheliosis virus (REV), infectious bursal disease virus (IBDV), avian leukosis virus (ALV), Newcastle disease virus (NDV), chicken infectious anemia virus (CIAV), infectious laryngotracheitis virus (ILTV), Marek's disease virus (MDV), and H9N2 avian influenza virus (H9N2), demonstrating high specificity. When compared to qPCR detection results, our method achieved a sensitivity of 96.67%, a specificity of 90%, and a Kappa value of 0.87 for the IBV CH I–V and Mass genotypes, and achieved a sensitivity of 100%, a specificity of 97.73%, and a Kappa value of 0.91 for the IBV CH VI genotype. [ABSTRACT FROM AUTHOR]

Avian Infectious Bronchitis Virus, has become one of the most problematic causes of economic losses in poultry farms. To effectively control the virus, monitoring and surveillance of circulating virus strains in poultry farms is inevitable. Internal organ samples of broilers with clinical signs of infectious bronchitis and two samples of the commonly used vaccine strains (4/91 and H120) in Iranian poultry flocks were used for amplification of a 1.8 kbp fragment including nucleocapsid (N) gene and 3′ untranslated region (UTR) by reverse transcription polymerase chain reaction (RTPCR) method. The amplified fragments were digested with the restriction endonuclease enzyme, AluI. The sequence similarity of the field isolate (Ma1/16) with previous isolates and reference strains of IBV was then investigated. Also, the phylogenetic relationship of Ma1/16 with viruses from other regions was determined based on the sequence of two 600 bp partial sequences of the N gene using Mega7 software. Seven IBVs were classified into two groups based on restriction fragment length polymorphism (RFLP) patterns of the N-3´ UTR fragment; all of five field isolates and vaccine strain 4/91 were clustered together. Ma1/16 had the highest similarity with two other Iranian IBV isolates, Ur1/09 and MNS-7861-1 (91.7 % and 90 %, respectively), based on the 600 nucleotides of 5´ end of the N-3' UTR fragment of the isolate. The nucleotide sequence of 600 nucleotides at the 3´ end of the amplified fragment in the Ma1/16 isolate (N-3' UTR) had the highest similarity to the BJ strain (86.4%). Regarding the induction of humoral and cellular immune responses using a vaccine candidate based on T-cell epitope peptides in IBV nucleocapsid protein, the gene sequence data of N-3'UTR fragment can be helpful in monitoring of circulating strains of IBV, designing effective IBV vaccines, and successfully controlling IB disease in Iran. [ABSTRACT FROM AUTHOR]

Adenoviruses are commonly found in chickens, and can be isolated from both sick and apparently healthy birds. Inclusion body hepatitis (IBH) is an acute disease primarily caused by (Fowl adeno virus) FAdV strains from groups D and E, including FAdV-8a serotype. Acknowledged for its immunosuppressive effects, we undertook an investigation into the early infection dynamics of IBH and its consequential impact on a fundamental vaccine widely employed in the poultry industry. Our study precisely examined the interplay between early IBH infection and the efficacy of a specific (Infectious bronchitis) IB vaccine. In this study, a total of 150 broiler chicks were divided into five groups, each consistedof 30 chicks. Group I received one dose of the IB variant vaccine, Group II and III received two doses (the first at 1-day-old and the second at 14-day-old), Group IV (control +ve) and Group V (control -ve). Groups I, II and IV were infected with IBH at 7-day-old. The evaluation encompassed diverse parameters, including clinical manifestations, mortality rates, and histopathological assessments of the liver, trachea, and kidney. Additionally, viral shedding of the IB vaccinal strain was examined. Our findings focus the detrimental impact of early IBH infection on avian organs and IB vaccinal strain shedding. Pronounced necrotic changes were observed in the tissues, coupled with an elevated viral shedding of the variant strain. These results collectively imply an augmented risk of potential outbreaks, emphasizing the need for a nuanced approach in managing IBH in the context of vaccination strategies. [ABSTRACT FROM AUTHOR]

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Simple Summary: The live attenuated infectious bronchitis virus vaccine strain QXL87 was derived from the parental virulent strain JS/2010/12 through serial passages in specific pathogen-free (SPF) chicken embryos. However, the molecular mechanism underlying its attenuation remains unknown. In this study, the complete genome sequences of both strains were obtained through next-generation sequencing technology. By comparing amino acids, protein structures, and functional sites, three potential virulence genes (Nsp2, Nsp3, and S) were identified as likely contributors to altering viral pathogenicity. Furthermore, analysis of the effects of single amino acid mutations on protein function and stability revealed three potential functional mutation sites: P106S (Nsp2), A352T (Nsp2), and L472F (Nsp2). This research provides an initial insight into the molecular basis of IBV attenuation and is expected to facilitate the development of new vaccines. The QXL87 live attenuated vaccine strain for infectious bronchitis represents the first approved QX type (GI-19 lineage) vaccine in China. This strain was derived from the parental strain CK/CH/JS/2010/12 through continuous passage in SPF chicken embryos. To elucidate the molecular mechanism behind its attenuation, whole-genome sequencing was conducted on both the parental and attenuated strains. Analysis revealed 145 nucleotide mutations in the attenuated strain, leading to 48 amino acid mutations in various proteins, including Nsp2 (26), Nsp3 (14), Nsp4 (1), S (4), 3a (1), E (1), and N (1). Additionally, a frameshift mutation caused by a single base insertion in the ORFX resulted in a six-amino-acid extension. Subsequent comparison of post-translational modification sites, protein structure, and protein–protein binding sites between the parental and attenuated strains identified three potential virulence genes: Nsp2, Nsp3, and S. The amino acid mutations in these proteins not only altered their conformation but also affected the distribution of post-translational modification sites and protein–protein interaction sites. Furthermore, three potential functional mutation sites—P106S, A352T, and L472F, all located in the Nsp2 protein—were identified through PROVEAN, PolyPhen, and I-Mutant. Overall, our findings suggest that Nsp2, Nsp3, and S proteins may play a role in modulating IBV pathogenicity, with a particular focus on the significance of the Nsp2 protein. This study contributes to our understanding of the molecular mechanisms underlying IBV attenuation and holds promise for the development of safer live attenuated IBV vaccines using reverse genetic approaches. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

SUMMARY Infectious laryngotracheitis (ILT) is a very serious worldwide respiratory disease of poultry, with many countries reporting ILT infections over the last decade. However, few reports are available regarding ILT disease prevalence in poultry in Turkey. Accordingly, the present study investigated ILT infection in Turkish broiler flocks between 2018 and 2022. Circulating ILT strains were characterized by sequence and phylogenetic analysis of two fragments of the infected-cell protein 4 gene. ILT virus (ILTV) was confirmed by quantitative PCR in 8 of the 21 flocks examined. As in other diseases, co-infections with other respiratory pathogens in confirmed ILT cases may worsen the symptoms and prolong the disease course. The present study confirmed co-infections with infectious bronchitis virus (13/21 tested flocks and 5/8 ILTV-positive flocks), indicating the importance of these pathogens in the occurrence of ILT infections. RESUMEN Circulación y caracterización molecular del virus de la laringotraqueítis infecciosa en bandadas de aves de corral con trastornos respiratorios en Turquía, 2018–2022. La laringotraqueítis infecciosa (ILT) es una enfermedad respiratoria muy seria de la industria avícola en todo el mundo y muchos países han notificado infecciones por esta enfermedad durante la última década. Sin embargo, hay pocos informes disponibles sobre la prevalencia de laringotraqueítis infecciosa en la avicultura de Turquía. En consecuencia, el presente estudio investigó la infección por laringotraqueítis infecciosa en parvadas de pollos de engorde en Turquía entre los años 2018 y 2022. Las cepas de laringotraqueítis infecciosa circulantes se caracterizaron mediante análisis de secuencias y filogenéticos de dos fragmentos del gene de la proteína 4 de las células infectadas. El virus ILT (ILTV) se confirmó mediante PCR cuantitativa en ocho de las 21 parvadas examinadas. Como ocurre con otras enfermedades, las coinfecciones con otros patógenos respiratorios en casos confirmados de laringotraqueítis infecciosa pueden complicar los signos clínicos y prolongar el curso de la enfermedad. El presente estudio confirmó coinfecciones con el virus de la bronquitis infecciosa (en 13/21 parvadas analizadas y en 5/8 parvadas positivas para laringotraqueítis infecciosa), lo que indica la importancia de estos patógenos en la aparición de infecciones por la laringotraqueítis infecciosa. [ABSTRACT FROM AUTHOR]

SUMMARY Outbreaks of infectious bronchitis (IB) continue to occur from novel variants of IB virus (IBV) emerging from selection of vaccine subpopulations and/or naturally occurring recombination events. S1 sequencing of Arkansas (Ark) -type viruses obtained from clinical cases in Alabama broilers and backyard chickens shows both Ark Delmarva Poultry Industry (ArkDPI) vaccine subpopulations as well as Ark vaccine viruses showing recombination with other IB vaccine viruses. IB Ark-type isolates AL5, most similar to an ArkDPI vaccine subpopulation selected in chickens, AL4, showing a cluster of three nonsynonymous changes from ArkDPI subpopulations selected in chickens, and AL9, showing recombination with Massachusetts (Mass) -type IBV, were examined for pathogenicity and ability to break through immunity elicited by vaccination with a commercial ArkDPI vaccine. Analysis of predicted S1 protein structures indicated the changes were in regions previously shown to comprise neutralizing epitopes. Thus, they were expected to contribute to immune escape and possibly virulence. Based on clinical signs, viral load, and histopathology, all three isolates caused disease in naïve chickens, although AL9 and AL5 viral loads in trachea were statistically significantly higher (30- and 40-fold) than AL4. S1 gene sequencing confirmed the stability of the relevant changes in the inoculated viruses in the chickens, although virus in some individual chickens exhibited additional S1 changes. A single amino acid deletion in the S1 NTD was identified in some individual chickens. The location of this deletion in the predicted structure of S1 suggested the possibility that it was a compensatory change for the reduced ability of AL4 to replicate in the trachea of naïve chickens. Chickens vaccinated with a commercial ArkDPI vaccine at day of hatch and challenged at 21 days of age showed that vaccination provided incomplete protection against challenge with these viruses. Moreover, based on viral RNA copy numbers in trachea, differences were detected in the ability of the vaccine to protect against these IBV isolates, with the vaccine protecting the most poorly against AL4. These results provide additional evidence supporting that IBV attenuated vaccines, especially ArkDPI vaccines, contribute to perpetuating the problem of IB in commercial chickens. RESUMEN Protección contra los virus de la bronquitis infecciosa vacunales recombinantes y las subpoblaciones de vacunas seleccionadas en pollos. Los brotes de la bronquitis infecciosa aviar continúan presentándose a partir de nuevas variantes de dicho virus, que surgen de la selección de subpoblaciones de vacunas y/o eventos de recombinación que ocurren naturalmente. La secuenciación del gene S1 de virus tipo Arkansas (Ark) obtenidos de casos clínicos en pollos de engorde y de traspatio de Alabama muestra que tanto las subpoblaciones de la cepa vacunal Arkansas Delmarva Poultry Industry (ArkDPI) así como los virus de la vacuna Arkansas muestran recombinación con otros virus vacunales de la bronquitis infecciosa. Los aislamientos del virus de la bronquitis infecciosa Arkansas tipo "AL5", más similares a una subpoblación de vacuna ArkDPI seleccionada en pollos, "AL4", que muestra un grupo de tres cambios no sinónimos de subpoblaciones de ArkDPI seleccionadas en pollos y el tipo "AL9", que muestra recombinación con el serotipo Massachusetts, se examinaron para determinar su patogenicidad y capacidad para traspasar la inmunidad generada por la vacunación con una vacuna comercial ArkDPI. El análisis de las estructuras predichas de la proteína S1 indicó que los cambios se produjeron en regiones que previamente se había demostrado comprendían epítopos neutralizantes. Por lo tanto, se esperaba que contribuyeran al escape inmunológico y posiblemente a la virulencia. Con base en los signos clínicos, la carga viral y la histopatología, los tres aislados causaron enfermedad en pollos sin exposición previa, aunque las cargas virales de AL9 y AL5 en la tráquea fueron estadísticamente significativamente mayores (30 y 40 veces) en comparación con AL4. La secuenciación del gene S1 confirmó la estabilidad de los cambios relevantes en los virus inoculados en los pollos, aunque el virus en algunos pollos individuales exhibió cambios adicionales en el gene S1. Se identificó una deleción de un solo aminoácido en el dominio terminal N del gene S1 (NTD S1) en algunos pollos individuales. La ubicación de esta eliminación en la estructura predicha del gene S1 sugirió la posibilidad de que se tratara de un cambio compensatorio por la capacidad reducida de AL4 para replicarse en la tráquea de pollos sin exposición previa. Los pollos vacunados con una vacuna comercial ArkDPI el día de la eclosión y desafiados a los 21 días de edad mostraron que la vacunación proporcionó una protección incompleta contra el desafío con estos virus. Además, basándose en el número de copias del ARN viral en la tráquea, se detectaron diferencias en la capacidad de la vacuna para proteger contra estos aislados del virus de la bronquitis infecciosa, siendo la vacuna con la protección más deficiente contra AL4. Estos resultados proporcionan evidencia adicional que respalda que las vacunas atenuadas contra el virus de la bronquitis infecciosa, especialmente las vacunas ArkDPI, contribuyen a perpetuar esta enfermedad en los pollos comerciales. [ABSTRACT FROM AUTHOR]

Infectious bronchitis (IB) is a disease with significant economic impacts both on the costs of control strategies and on productive losses. Various vaccination protocols are applied, depending on homologous or heterologous protection against IB and finding the optimal balance between costs and benefits as a choice by a responsible veterinarian. The current case study aimed to demonstrate the efficacy of a heterologous vaccine combination against field IBV GI-23 (Variant 2) infection when vaccination quality was properly monitored. Two groups, each consisting of six flocks, were examined before and after improving the quality of IB vaccine application in the hatchery. These groups were vaccinated with H-120 and 1/96 vaccine strains for heterologous protection. The study involved field visits, necropsies, serology via ELISA, and oropharyngeal sampling for RT-PCR follow-up activities. Moreover, performance parameters including average body weight, feed conversion ratio, and 7 days plus total mortality were analyzed at the end of the production cycle at 40-45 days of age. Results indicated that the group with enhanced vaccination quality in the hatchery exhibited a significant decrease in IBV titers and an absence of IBV GI-23 field infection. Additionally, there was an improvement in performance data in terms of average body weight, FCR and total mortality. Hatchery vaccination proved to be more controllable and practical compared to traditional on-farm vaccination, ensuring better control of the vaccination process and massive coverage of the farm population. [ABSTRACT FROM AUTHOR]

Infectious Bronchitis (IB) is a viral respiratory disease of chickens that is associated with huge economic losses. This study was designed to investigate its seroprevalence in unvaccinated exotic and indigenous chickens in some States of South-western Nigeria. Sera samples (n=750) were obtained from unvaccinated, intensively reared, exotic chickens (n=450) and unvaccinated extensively reared indigenous chickens (n=300) from Lagos, Ogun, and Oyo States. The antibodies to the IB virus were detected in serum utilizing enzyme-linked immunosorbent assay. Descriptive statistics, ANOVA, and an independent t-test were used to analyze the data. On average, 81.1% were seropositive to IB virus, distributed as 78.0%, 86.8%, and 78.4% in Lagos, Ogun, and Oyo States, respectively. Seroprevalence was high in both exotic (82.4%) and indigenous (79.0%) chickens, while mean antibody titres were significantly higher in exotic (49.74 ± 2.50 and 43.25 ± 4.64) than in indigenous chickens (24.71 ± 2.02 and 31.85 ± 2.24) in Lagos and Oyo states, respectively. Indigenous chickens raised in south-western Nigeria are likely exposed to infectious bronchitis virus in the environment and the presence of the antibodies in these chickens is an indicator of the endemicity of the virus. This also identifies a possible role for indigenous chickens in the dissemination of the virus. There is a need for continuous surveillance, improved vaccination, and stricter biosecurity measures in poultry production for optimal control of infectious bronchitis in Nigeria. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) is a coronavirus that infects chickens, which exhibits a broad tropism for epithelial cells, infecting the tracheal mucosal epithelium, intestinal mucosal epithelium, and renal tubular epithelial cells. Utilizing single-cell RNA sequencing (scRNA-seq), we systematically examined cells in renal, bursal, and tracheal tissues following IBV infection and identified tissue-specific molecular markers expressed in distinct cell types. We evaluated the expression of viral RNA in diverse cellular populations and subsequently ascertained that distal tubules and collecting ducts within the kidney, bursal mucosal epithelial cells, and follicle-associated epithelial cells exhibit susceptibility to IBV infection through immunofluorescence. Furthermore, our findings revealed an upregulation in the transcription of proinflammatory cytokines IL18 and IL1B in renal macrophages as well as increased expression of apoptosis-related gene STAT in distal tubules and collecting duct cells upon IBV infection leading to renal damage. Cell-to-cell communication unveiled potential interactions between diverse cell types, as well as upregulated signaling pathways and key sender-receiver cell populations after IBV infection. Integrating single-cell data from all tissues, we applied weighted gene co-expression network analysis (WGCNA) to identify gene modules that are specifically expressed in different cell populations. Based on the WGCNA results, we identified seven immune-related gene modules and determined the differential expression pattern of module genes, as well as the hub genes within these modules. Our comprehensive data provides valuable insights into the pathogenesis of IBV as well as avian antiviral immunology. Author summary: A comprehensive understanding of the pathogenesis of IBV in chickens is crucial for the development of effective control and prevention strategies. In our study, we conducted single-cell RNA sequencing analyses on chicken kidney, bursa, and tracheal tissues to systematically uncover the cell types targeted by IBV infection and to delineate the immune response patterns and key genes within immune gene modules in different tissues. Consequently, this research holds the potential to provide novel targets and directions for the prevention of IBV. [ABSTRACT FROM AUTHOR]

This study aims to identify and characterize receptor binding sites (RBS) and antigenic sites (HVR-I and II) of the S1 gene fragment of the infectious bronchitis virus (IBV) isolated and propagated from commercial chickens in Java Region to monitor recent circulating virus. The samples in this study were the organs which indicated infectious bronchitis infection. The stages of this research consisted of making virus suspensions, isolation, and propagation, as well as molecular detection and characterization of viruses. Virus isolation and propagation were carried out on chicken embryonated eggs aged 11 days via the allantoic route. Culture confirmation was performed by RT-PCR of the S1 gene fragment, followed by sequencing and bioinformatics analysis. The 168-hour propagation was observed in both dwarfed and curled embryos of two isolates from 11 isolates detected as IBV-positive. Phylogenetic tree construction resulted in all isolates being grouped as GI-19 genotype (QX-like). Amino acid identity among QX-like strains was calculated at 87-100%. A total of 210 predicted amino acid residues were observed, including 31 substitutions and 2 deletions. Conclusions of this study were identified and characterized as GI-19 genotype (QX-like) IBV with amino acid changes on S1 fragment from breeder, broiler, and layer chickens in Java Region. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) has a variety of serotypes that cause many problems in the poultry industry. Two H120 and H120-D274 live vaccines were evaluated against strain IS/1494/06 (variant 2) IBV challenge. The study aimed to determine whether it was possible to achieve success in controlling disease symptoms and pathological lesions and reducing virus shedding by combining two types of vaccines against different severities of poultry IBV. After random selection of 100 specific pathogen-free chickens, four 25 chicks/group experimental groups were arranged in the H120 (IB-H120, Intervet®; Serial No: **** at 1st day + Booster 14th day + Challenged with IS/1494/06- 14 DPV), H120-D274 (Poulvac® IB Primer at 1st day + Booster 14th day + Challenged with IS/1494/06- 14 DPV), Control (No vaccine + No Challenge), and Challenged (No vaccine + Challenge). After euthanasia of the animals on the 42nd day of the research, serum neutralization (days 14, 28, and 42), ELISA (14 days after the booster vaccine and before challenged), Ciliostasis (7 days after the booster vaccine and seven days after challenged), and pathological lesion scores were evaluated on day 14 after being infected with IS/1494/06 type 2 strain (day 42). Moreover, the virus shedding was monitored by real-time polymerase chain reaction. Infection with the IS/1494/06 variant 2 strain showed high to moderate ciliostasis and pathologic scores. All groups that received the IB-H120-D274 vaccine had fewer lesions relatively. The IB-H120-D274 vaccinated groups showed the highest protection rates and high protection scores (70.3) than the IB-H120 vaccine groups (24.4). The virus shedding was significantly reduced in groups that received the H120-D274 vaccine compared to those that received the IB-H120 vaccine. In conclusion, the homologous IB-H120-D274 vaccine showed superior results compared to the IB-H120 vaccine. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) is a highly contagious Gammacoronavirus causing moderate to severe respiratory infection in chickens. Understanding the initial antiviral response in the respiratory mucosa is crucial for controlling viral spread. We aimed to characterize the impact of IBV Delmarva (DMV)/1639 and IBV Massachusetts (Mass) 41 at the primary site of infection, namely, in chicken tracheal epithelial cells (cTECs) in vitro and the trachea in vivo. We hypothesized that some elements of the induced antiviral responses are distinct in both infection models. We inoculated cTECs and infected young specific pathogen-free (SPF) chickens with IBV DMV/1639 or IBV Mass41, along with mock-inoculated controls, and studied the transcriptome using RNA-sequencing (RNA-seq) at 3 and 18 h post-infection (hpi) for cTECs and at 4 and 11 days post-infection (dpi) in the trachea. We showed that IBV DMV/1639 and IBV Mass41 replicate in cTECs in vitro and the trachea in vivo, inducing host mRNA expression profiles that are strain- and time-dependent. We demonstrated the different gene expression patterns between in vitro and in vivo tracheal IBV infection. Ultimately, characterizing host–pathogen interactions with various IBV strains reveals potential mechanisms for inducing and modulating the immune response during IBV infection in the chicken trachea. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) causes a highly contagious respiratory disease in chickens, leading to significant economic losses in the poultry industry worldwide. IBV exhibits a high mutation rate, resulting in the continuous emergence of new variants and strains. A complete genome analysis of IBV is crucial for understanding its characteristics. However, it is challenging to obtain whole-genome sequences from IBV-infected clinical samples due to the low abundance of IBV relative to the host genome. Here, we present a novel approach employing next-generation sequencing (NGS) to directly sequence the complete genome of IBV. Through in silico analysis, six primer pairs were designed to match various genotypes, including the GI-19 lineage of IBV. The primer sets successfully amplified six overlapping fragments by long-range PCR and the size of the amplicons ranged from 3.7 to 6.4 kb, resulting in full coverage of the IBV genome. Furthermore, utilizing Illumina sequencing, we obtained the complete genome sequences of two strains belonging to the GI-19 lineage (QX genotype) from clinical samples, with 100% coverage rates, over 1000 × mean depth coverage, and a high percentage of mapped reads to the reference genomes (96.63% and 97.66%). The reported method significantly improves the whole-genome sequencing of IBVs from clinical samples; thus, it can improve understanding of the epidemiology and evolution of IBVs. [ABSTRACT FROM AUTHOR]

This document provides a summary of three different articles related to avian infectious bronchitis (IBV). The first article discusses a study that evaluated the efficacy of commercially available vaccines against the local Thai QX field strain of IBV in specific pathogen-free (SPF) chicks. The study found that a combination of TAbic IB VAR (233A) or Ibird (1/96) vaccine with a Massachusetts serotype vaccine (H120) was effective in protecting SPF chicks against the local Thai QX strain. The second article discusses a study on the effectiveness of different vaccination programs in protecting chickens against the QX-like virus, a strain of IBV prevalent in Thailand. The study found that a combination of the 793/B vaccine and the Massachusetts serotype vaccine showed significant protective efficacy against the local Thai QX-like virus in chickens. The third document is a list of references related to avian infectious bronchitis, providing a comprehensive overview of research on the topic from various countries. [Extracted from the article]

Equine herpesvirus type 8 (EHV-8) causes abortion and respiratory disease in horses and donkeys, leading to serious economic losses in the global equine industry. Currently, there is no effective vaccine or drug against EHV-8 infection, underscoring the need for a novel antiviral drug to prevent EHV-8-induced latent infection and decrease the pathogenicity of this virus. The present study demonstrated that hyperoside can exert antiviral effects against EHV-8 infection in RK-13 (rabbit kidney cells), MDBK (Madin-Darby bovine kidney), and NBL-6 cells (E. Derm cells). Mechanistic investigations revealed that hyperoside induces heme oxygenase-1 expression by activating the c-Jun N-terminal kinase/nuclear factor erythroid-2-related factor 2/Kelch-like ECH-associated protein 1 axis, alleviating oxidative stress and triggering a downstream antiviral interferon response. Accordingly, hyperoside inhibits EHV-8 infection. Meanwhile, hyperoside can also mitigate EHV-8-induced injury in the lungs of infected mice. These results indicate that hyperoside may serve as a novel antiviral agent against EHV-8 infection. IMPORTANCE Hyperoside has been reported to suppress viral infections, including herpesvirus, hepatitis B virus, infectious bronchitis virus, and severe acute respiratory syndrome coronavirus 2 infection. However, its mechanism of action against equine herpesvirus type 8 (EHV-8) is currently unknown. Here, we demonstrated that hyperoside significantly inhibits EHV-8 adsorption and internalization in susceptible cells. This process induces HO-1 expression via c-Jun N-terminal kinase/nuclear factor erythroid-2-related factor 2/Kelch-like ECH-associated protein 1 axis activation, alleviating oxidative stress and triggering an antiviral interferon response. These findings indicate that hyperoside could be very effective as a drug against EHV-8. [ABSTRACT FROM AUTHOR]

Infectious bronchitis (IBV) is an economically important acute, highly contagious disease affecting poultry worldwide. The primary place of IBV replication is the upper respiratory tract from where infection can spread to reproductive organs causing a decrease in egg production and the occurrence of misshapen eggs, changes in shells, and watery albumen leading to lowquality eggs. In our study, samples were submitted to determine causative agents that resulted in respiratory signs of hens and altered egg quality. The hen carcass was inspected by gross pathology and histopathology. Based on pathological findings, tissue samples of the trachea, kidney, ovary, and tracheal and cloacal swabs were tested by rtRT-PCR using two sets of primers. Histopathology findings and the first set of primers confirmed the presence of coronavirus in the tracheal tissue sample. This sample was further tested with an IBV-specific set of primers which undoubtedly confirmed the presence of IBV RNA. Although IBV vaccination in our country is common practice, this study shows that despite vaccines it can come to breach of IBV infection that could cause substantial economic losses. Eggs are considered one of the primal sources of protein, and shells as the primal barrier against microorganisms, must not have any defects to secure eggs' quality and safety. IBV infection does not represent a risk to public health, but its occurrence in production may result in low egg quality and difficulties in the placement of the product on the market. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) is a respiratory virus causing atropism in multiple body systems of chickens. Recently, the California 1737/04 (CA1737/04) IBV strain was identified as one of the circulating IBV variants among poultry operations in North America. Here, the pathogenicity and tissue tropism of CA1737/04 IBV strain in specific-pathogen-free (SPF) hens were characterized in comparison to Massachusetts (Mass) IBV. In 30 weeks-old SPF hens, Mass or CA1737/04 IBV infections were carried out, while the third group was maintained as a control group. Following infection, we evaluated clinical signs, egg production, viral shedding, serology, necropsy examination, and histopathology during a period of 19 days. Also, certain tissue affinity parameters were investigated, which involved the localization of viral antigens and the detection of viral RNA copies in designated tissues. Our findings indicate that infection with CA1737/04 or Mass IBV strain could induce significant clinical signs, reduced egg production, and anti-IBV antibodies locally in oviduct wash and systemically in serum. Both IBV strains showed detectable levels of viral RNA copies and induced pathology in respiratory, renal, enteric, and reproductive tissues. However, the CA1737/04 IBV strain had higher pathogenicity, higher tissue tropism, and higher replication in the kidney, large intestine, and different segments of the oviduct compared to the Mass IBV strain. Both IBV strains shed viral genome from the cloacal route, however, the Mass IBV infected hens shed higher IBV genome loads via the oropharyngeal route compared to CA1737/04 IBV-infected hens. Overall, the current findings could contribute to a better understanding of CA1737/04 IBV pathogenicity in laying hens. [ABSTRACT FROM AUTHOR]

The viral diseases that occurred in recent years have increased the interest in non-toxic to healthy cells and naturally isolated agents to struggle with these diseases. The key intention of this research is to examine both antiviral potentials against the Infectious Bronchitis model virus (IBV) and cytotoxic activities on determined cell lines of different active ingredients and medical herbs extracts for developing new antiviral agents or drugs towards SARS-CoV-2. The antiviral potency of the samples against IBV was determined as in ovo virucidal antiviral activity in specific pathogen-free (SPF) embryonated chicken eggs (ECEs). To detect antiviral activity, the haemagglutination test was performed after 48 h of incubation for all samples. The cytotoxic activity of the samples was identified on HepG2, Caco-2, HeLa, HEK293, PANC-1, PC-3, A549, MDAMB-231, and CCD-34Lu cell lines by the MTT protocol. Hypericum perforatum extract was found to have a dominant role in cytotoxicity and antiviral activity. In addition, while nobiletin and Sambucus nigra do not exhibit cytotoxic activity on cells, they play a significant role in antiviral activity. As a consequence of our investigation, the cytotoxic and antiviral properties of Laurus nobilis, H. perforatum, and S. nigra extracts were found remarkable and the potential of these extracts was demonstrated. [ABSTRACT FROM AUTHOR]

The GI-19 lineage of infectious bronchitis virus (IBV) has emerged as one of the most impactful, particularly in the "Old World". Originating in China several decades ago, it has consistently spread and evolved, often forming independent clades in various areas and countries, each with distinct production systems and control strategies. This study leverages this scenario to explore how different environments may influence virus evolution. Through the analysis of the complete S1 sequence, four datasets were identified, comprising strains of monophyletic clades circulating in different continents or countries (e.g., Asia vs. Europe and China vs. Thailand), indicative of single introduction events and independent evolution. The population dynamics and evolutionary rate variation over time, as well as the presence and intensity of selective pressures, were estimated and compared across these datasets. Since the lineage origin (approximately in the mid-20th century), a more persistent and stable viral population was estimated in Asia and China, while in Europe and Thailand, a sharp increase following the introduction (i.e., 2005 and 2007, respectively) of GI-19 was observed, succeeded by a rapid decline. Although a greater number of sites on the S1 subunit were under diversifying selection in the Asian and Chinese datasets, more focused and stronger pressures were evident in both the European (positions 2, 52, 54, 222, and 379 and Thai (i.e., positions 10, 12, 32, 56, 62, 64, 65, 78, 95, 96, 119, 128, 140, 182, 292, 304, 320, and 323) strains, likely reflecting a more intense and uniform application of vaccines in these regions. This evidence, along with the analysis of control strategies implemented in different areas, suggests a strong link between effective, systematic vaccine implementation and infection control. However, while the overall evolutionary rate was estimated at approximately 10−3 to 10−4, a significant inverse correlation was found between viral population size and the rate of viral evolution over time. Therefore, despite the stronger selective pressure imposed by vaccination, effectively constraining the former through adequate control strategies can efficiently prevent viral evolution and the emergence of vaccine-escaping variants. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) induces severe economic losses in chicken farms due to the emergence of new variants leading to vaccine breaks. The studied IBV strains belong to Massachusetts (Mass), Canadian 4/91, and California (Cal) 1737 genotypes that are prevalent globally. This study was designed to compare the impact of these three IBV genotypes on primary and secondary lymphoid organs. For this purpose, one-week-old specific pathogen-free chickens were inoculated with Mass, Canadian 4/91, or Cal 1737 IBV variants, keeping a mock-infected control. We examined the IBV replication in primary and secondary lymphoid organs. The molecular, histopathological, and immunohistochemical examinations revealed significant differences in lesion scores and viral distribution in these immune organs. In addition, we observed B-cell depletion in the bursa of Fabricius and the spleen with a significant elevation of T cells in these organs. Further studies are required to determine the functional consequences of IBV replication in lymphoid organs. [ABSTRACT FROM AUTHOR]

Emergence of new variants of infectious bronchitis virus is a continuous threat to poultry industry in Pakistan which is causing unusual outbreaks resulting in high mortality in chickens. The present study was designed to investigate the presence of newly emerging variants of IBV through molecular characterization, S1 gene amplification and phylogenetic analysis. A total of 412 outbreaks were investigated which affected flocks in Multan, Lahore, Rawalpindi and Abbottabad regions of Pakistan. At least five (05) suspected samples from each outbreak were collected and then pooled into a single sample. Out of these 412 samples, 138 were found positive showing an overall positivity of 33.49%. The phylogenetic analysis revealed that our six isolates (OL763341, OL763342, OL763343, OL763344, OL763345, OL763346) had a homology of 92-93% and 93-95% with three nephro-pathogenic strains (i.e., KX832222, KX832223 & KF809795) isolated in India and China while 97-98% with the Pakistani isolate (MK689242). Among other Pakistani isolates, 83% and 95% nucleotide similarity was found with two isolates (MH703660 and MH703657) on the basis of 390bp S1 gene sequences. These Pakistani reference strains were also of variant/untyped genotype. Further, when these isolates were subjected for in-ovo propagation in 10-days old embryonated chicken eggs, they induced IBV typical teratogenic effects in chicken embryos. It was concluded that despite regular vaccination, variant strains including nephro-pathogenic strains are involved in IB outbreaks in field in Pakistan. It is recommended that a country wise surveillance and vaccine cross protection study may be conducted to investigate and control the problem. [ABSTRACT FROM AUTHOR]

Background: Effect of antibacterials on mucociliary system and clinical outcome of chickens with mixed viral respiratory conditions is not properly addressed. Objective: We evaluated enrofloxacin effects on clinical parameters and mucociliary system of broilers challenged with H9N2/IB viruses. Methods: Broilers (105), at the age of 25 days, were randomly allocated into three groups: Group 1 (negative control), no treatment; Group 2 (positive control [PC]) challenged by intranasal and intraocular route. Group 3 (antibiotic [AB]‐treated) challenged and also received enrofloxacin started after manifestation of clinical signs (day 2 post‐challenge [pc]) and continued for 5 days. Results: Administration of AB was not associated with appreciable changes in body weight, feed conversion ratio (FCR) or the severity of clinical signs although it slightly reduced mortality rate as compared to PC group (p > 0.05). Virus shedding period and number of virus positive tracheal and caecal tonsil samples were also statistically similar between PC and AB groups. In necropsy, the most profound effect of AB was decreased pleuropneumonia severity score on day 12 pc. Histopathological lesion scores were statistically the same between PC and AB groups. However, the administration of AB increased the number of tracheal goblet cells, with no effect on ciliostasis. Conclusions: We found a weak positive effect of enrofloxacin administration in H9N2/IB‐infected chickens. Considering the risks of AB treatment in broiler chickens, the results of this small‐scale study do not encourage the benefit of enrofloxacin use in these viral diseases. [ABSTRACT FROM AUTHOR]