Chicken Infectious Bronchitis Research Articles

Коронавірусні інфекції тварин і птиці в контексті пандемічного поширення коронавірусної хвороби людей COVID-19 (стан і перспективи розв’язання проблеми)

Goal. Because of significant spread in the modern world of coronavirus infection of a man of a new type (COVID-19), caused by a virus SARS-CoV-2, to provide professional analysis of the nature and biological characteristics of coronaviruses of animals, their evolutionary and phylogenetic relationships with coronaviruses of a man, as well as to outline prospects for the use of animal coronaviruses in the creation of a system of countermeasures against pandemic COVID-19. Methods. The generalized literature data and the review of the achievements of scientists of NSC «IECVM» in the control of coronavirus infections in cattle and poultry are submitted for consideration. Results. Classification and phylogenetic relationships in the family Coronaviridae are given, as well as the review of own and literature data on the genetic and antigenic structure of coronavirus cattle. They characterized the direction of the creation of means of control of coronavirus infection of cattle (development of vaccines and diagnosticums). Circulation is established of the virus of infectious bronchitis of chickens «D 388 (QX)», «Italy 02», «4/91», «M41» in poultry farms of Ukraine. The immunity against infectious bronchitis of chickens is 93–100%. In the process of developing modern vaccine preparation for prevention of infectious diseases in poultry (Newcastle disease, infectious bronchitis of chickens and syndrome of decreased egg production) it is established that formaldehyde and ethylenimine completely inactivate the infectivity of the pathogens of the infections, while antigenic activity remains at a high level. The data are given of scientific researches in the ecology and biology of coronavirus infectious bronchitis of chickens, as well as in the study of the ultrastructure of the virus. Conclusions. Knowledge of biological properties and features of mammalian and poultry coronaviruses can be successfully applied in the tests on the effectiveness of control agents (medicines and disinfectants), for preventive actions (creation of «candidate» of vaccines), and control over Covid-19 infection.

Efficacy of Live Vaccines and Specific Prevention in Chicken Infectious Bronchitis

Infectious bronchitis of chickens (IBC) is a highly contagious disease characterized by damage to the respiratory tract. Adult chickens exhibit respiratory symptoms, a 10-50% decrease in egg production, discoloration of the eggshell, deformation of the shell, and a deterioration in the marketability and breeding quality of eggs. The circulation of variant strains in poultry farms of the Russian Federation causes a significant decrease in egg production and the quality of the eggs obtained, causing significant economic damage to industrial poultry farming. The study aimed to presents materials and methods for the industrial and efficient use of live-vaccines against infectious bronchitis of hens from a variant strain. After the use of a live vaccine against infectious bronchitis of chickens from a variant strain, the development, live weight of chickens, and feed conversion during the rearing period were within the standard parameters. in present study, the safety for the growing period with a planned 97.6% was 98.8-98.9%. The uniformity of the herds when transferred to hen - hen was 94-95%. When carrying out immunoprophylaxis of IBS, local immunity is important, which can be ensured using a live spray vaccine - a method starting from the day old. When establishing circulation in the economy of variant strains of IBC virus, it is necessary to introduce vaccination against the variant strain into the scheme of treatment and preventive measures. The research results allow us to conclude that, for the effective prevention of chicken infectious bronchitis, immunization against IBS from variant strains should be introduced into the vaccine prevention scheme.

Coronavirus SARS-CoV-2 (COVID-19) and Companion Animal Pets

Coronaviruses belong to a large family of related viruses that can infect and cause diseases of the respiratory and gastrointestinal tracts of mammals and birds [1-8]. The human strains were first identified in the 1960s and were the cause of common colds, which could lead to bronchitis and pneumonia [1-3]. Coronaviruses are zoonotic microbes that can jump between species and are transmitted between animals and people [3,4]. For example, the Severe Acute Respiratory Syndrome Coronavirus (SARS -CoV) of 2003 was transmitted by civet cats to humans, and the Middle Eastern Respiratory Syndrome (MERS-Co-V) of 2012-2018 had the dromedary camel as an intermediate host [1,2]. The SARS-CoV-2 virus that causes COVID -19 disease of 2019-2020 is believed to have been transmitted by bats, and not as originally thought by some to have arisen from certain snakes and ant-eating pangolins [4-6].The beta-coronavirus (SARS-CoV-2) outbreak that began in the Wuhan area of China in late 2019 has 70% genetic similarity to SARS-CoV and 96% similarity to a bat coronavirus, or even to a chimera of the two viruses [9]. The current spread of COVID-19 disease is a result of human to human transmission [3,4]. Most symptoms are mild but they can develop into severe respiratory infections in elderly people and those with compromised immunity (e.g, cardiovascular and respiratory diseases, and diabetes) [3]. Importantly, SARS-CoV-2 infection of COVID-19 disease has been proven by gene sequencing to have evolved naturally as a mutation and was not a lab-constructed or purposely manipulated virus [9]. Regarding the alpha-coronaviruses of animals, the bovine and canine strains developed from a common ancestor in about 1950 [7,8]. These viruses were recognized in veterinary medicine to cause pathological conditions since the early 1970s. All have been intestinal (enteric) infections except for avian (mostly chicken) infectious bronchitis, which also targets the urogenital tract [7]. For dogs, there are two coronaviruses, the most common form that can cause mild gastrointestinal tract symptoms, and a different rare respiratory form [7].In cats, feline coronavirus is mainly a mild enteric infection, but it can undergo spontaneous mutation in some cats to cause feline infectious peritonitis (FIP) with high morbidity and mortality. In other species, the porcine coronavirus causes transmissible gastroenteritis, and both the bovine and porcine viruses cause diarrhea in young animals. Ferrets, rabbits, rats, and mice are also infected. In bats, the most closely related coronavirus diverged from SARS in 1986 [3,4].

Three Amino Acid Changes in Avian Coronavirus Spike Protein Allow Binding to Kidney Tissue.

Infectious bronchitis virus (IBV) infects ciliated epithelial cells in the chicken respiratory tract. While some IBV strains replicate locally, others can disseminate to various organs, including the kidney. Here, we elucidate the determinants for kidney tropism by studying interactions between the receptor-binding domain (RBD) of the viral attachment protein spike from two IBV strains with different tropisms. Recombinantly produced RBDs from the nephropathogenic IBV strain QX and from the nonnephropathogenic strain M41 bound to the epithelial cells of the trachea. In contrast, only QX-RBD binds more extensively to cells of the digestive tract, urogenital tract, and kidneys. While removal of sialic acids from tissues prevented binding of all proteins to all tissues, binding of QX-RBD to trachea and kidney could not be blocked by preincubation with synthetic alpha-2,3-linked sialic acids. The lack of binding of QX-RBD to a previously identified IBV-M41 receptor was confirmed by enzyme-linked immunosorbent assay (ELISA), demonstrating that tissue binding of QX-RBD is dependent on a different sialylated glycan receptor. Using chimeric RBD proteins, we discovered that the region encompassing amino acids 99 to 159 of QX-RBD was required to establish kidney binding. In particular, QX-RBD amino acids 110 to 112 (KIP) were sufficient to render IBV-M41 with the ability to bind to kidney, while the reciprocal mutations in IBV-QX abolished kidney binding completely. Structural analysis of both RBDs suggests that the receptor-binding site for QX is located at a different location on the spike than that of M41.IMPORTANCE Infectious bronchitis virus is the causative agent of infectious bronchitis in chickens. Upon infection of chicken flocks, the poultry industry faces substantial economic losses by diminished egg quality and increased morbidity and mortality of infected animals. While all IBV strains infect the chicken respiratory tract via the ciliated epithelial layer of the trachea, some strains can also replicate in the kidneys, dividing IBV into the following two pathotypes: nonnephropathogenic (example, IBV-M41) and nephropathogenic viruses (including IBV-QX). Here, we set out to identify the determinants for the extended nephropathogenic tropism of IBV-QX. Our data reveal that each pathotype makes use of a different sialylated glycan ligand, with binding sites on opposite sides of the attachment protein. This knowledge should facilitate the design of antivirals to prevent coronavirus infections in the field.

Pathological and virological analysis of concurrent disease of chicken anemia virus infection and infectious bronchitis in Japanese native chicks.

A concurrent infection of chicken anemia virus (CAV) and infectious bronchitis virus (IBV) was detected in Japanese native chicks in 2017, in which a high mortality rate (97.7%) was recorded in a small flock of 130 chicks exhibiting poor growth. Histological examination revealed that the affected chicks exhibited two different pathological entities: one was severe hematopoietic and lymphocytic depletion with abnormally large cells containing intranuclear inclusion bodies of CAV, whereas the other was renal tubular necrosis due to IBV infection. Immunohistochemistry detected CAV antigens in the bone marrow, liver, and spleen as well as IBV antigens in the kidneys, trachea, and air sacs. CAV was isolated from the liver sample of the chicks, and the isolated strain was designated as CAV/Japan/HS1/17. A phylogenetic analysis of the CAV VP1 gene revealed that CAV/Japan/HS1/17 is genetically similar to Chinese strains collected from 2014 to 2016. An experimental infection was performed using CAV/Japan/HS1/17 and specific-pathogen-free chicks to determine the pathogenicity of CAV/Japan/HS1/17. The isolate caused 100% anemia and 70% mortality to chicks inoculated at one day old, 80% of chicks inoculated at seven days old also developed anemia, and 10% died from CAV infection. These results suggest that the unusually high mortality in Japanese native chicks can be attributed to dual infection with both CAV and IBV. The results of the experimental infection suggest that CAV/Japan/HS1/17 has a pathogenic potential to specific-pathogen-free chicks and a relatively higher pathogenicity than previous Japanese CAV strains.

Microstructure of replacement chickens’ spleen after immunostimulant application

The article presents the histological studies of replacement chickens’ spleen. The predominance of medium lymphocytes over small ones in the periarterial area was noted after vaccination with “Raspol” being an immunostimulant against chicken infectious bronchitis. In the periarterial area, the predominance of medium lymphocytes over small ones was noted. The lumen profiles of the central, trabecular arteries were well defined, and there were no signs of connective tissue disorganization in their walls. The marginal part of the lymph nodules also remained well defined especially from the inner border and consisted of a large number of small lymphocytes and fewer medium ones. However, its width decreased markedly compared to the previous period of the organ examination. The indicated changes denote the signs of lymphoid cell hyperplasia in the lymph nodes, with a weak severity or absence of the consequences of the vaccine reactogenic effect on the connective tissue of the organ. In the birds receiving Fosprenil during immunization, the stimulation of lymphoproliferative activity continued during the first two weeks after vaccination and by the end of the one-month period it was not detected. However, signs of moderate postvaccination disorganization of the connective tissue components were observed at all follow-up periods. 28 days after vaccination, lymphoproliferative processes weakened markedly and signs accompanied by moderate disorganization of the components in connective tissue persisted in the spleen of the control group of birds.

Peptides with 16R in S2 protein showed broad reactions with sera against different types of infectious bronchitis viruses

Vaccination plays a vital role in controlling diseases caused by chicken infectious bronchitis virus (IBV). The continuously variant antigenicity of IBV limits the application of current vaccine strategies and serological diagnostic systems. S2 protein is an invariant that harbors broad neutralizing epitopes. However, little is known about the key amino acids that contribute to the broad-spectrum S2 epitopes. In this study, we aimed to elucidate the specific amino acids contributing to S2 epitopes. Site mutagenesis and peptide-based enzyme-linked immunosorbent assays (ELISAs) showed that 16R in S2 protein was a key amino acid mediating the antigenicity of S2 protein. S2-derived peptides with 16R, but not those with 16 K, could react with sera against different types of IBVs. Notably, a commercial ELISA kit for detection of antibodies against IBV did not react with sera against all types of IBVs. Taken together, these data demonstrated that S2-derived peptides with 16R could be used as novel marker-based antigens for developing both broad-spectrum vaccines and serological diagnostic kits to control IBV.

Evaluation of bacteriophage efficacy in reducing the impact of single and mixed infections with Escherichia coli and infectious bronchitis in chickens

ABSTRACTInfectious bronchitis virus (IBV) represents a major threat to poultry production worldwide particularly when complicated with bacterial infection. In the present study samples were collected from forty broiler farms with respiratory manifestations to characterize IBV and E. coli. Bacteriophages were isolated and enriched from sampled farms to study its efficacy to control single and mixed infections with E. coli and IBV in vivo. Twelve out of forty farms were positive for IBV. Phylogenetic analysis of partial spike protein revealed that all positive cases clustered within the GI-23 genotype. Eight out of forty farms were positive for E. coli serogroups O26, O78, O86, O114, O119, with O125 found on three farms. Bacteriophage treatment delayed the onset and reduced the severity of clinical signs, and prevented the mortality associated with single and mixed infection with IBV and E. coli. Furthermore, in mixed infections, bacteriophage treatment significantly reduced E. coli as well as IBV shedding. Groups treated with bacteriophages showed a significant reduction of E. coli shedding that gradually decreased over time, in contrast to higher and gradually increasing shedding without bacteriophage treatment. In conclusion, bacteriophage treatment significantly reduced the pathogenicity and shedding of IBVand E. coli in mixed infections.

Oral immunization with a novel attenuated Salmonella Gallinarum encoding infectious bronchitis virus spike protein induces protective immune responses against fowl typhoid and infectious bronchitis in chickens

Fowl typhoid (FT), a septicemic disease caused by Salmonella Gallinarum (SG), and infectious bronchitis (IB) are two economically important avian diseases that affect poultry industry worldwide. Herein, we exploited a live attenuated SG mutant, JOL967, to deliver spike (S) protein 1 of IB virus (V) to elicit protective immunity against both FT and IB in chickens. The codon optimized S1 nucleotide sequence was cloned in-frame into a prokaryotic constitutive expression vector, pJHL65. Subsequently, empty pJHL65 or recombinant pJHL65-S1 plasmid was electroporated into JOL967 and the resultant clones were designated as JOL2068 and JOL2077, respectively. Our results demonstrated that the chickens vaccinated once orally with JOL2077 elicited significantly (p < 0.05) higher IBV-specific humoral and cell-mediated immunity compared to JOL2068 and PBS control groups. Consequently, on challenge with the virulent IBV strain at 28th day post-vaccination, JOL2077 vaccinated birds displayed significantly (p < 0.05) lower inflammatory lesions in virus-targeted tissues compared to control groups. Furthermore, 33.3% (2 of 6) of birds vaccinated with JOL2077 vaccine had shown virus recovery from tracheal tissues compared to 100% (6 of 6) recovery obtained in both the control groups. Against wild-type SG lethal challenge, both JOL2077 and JOL2068 vaccinated groups exhibited only 10% mortality compared to 80% mortality observed in PBS control group. In conclusion, we show that JOL2077 can induce efficient IBV- and carrier-specific protective immunity and can act as a bivalent vaccine against FT and IB. Further studies are warranted to investigate the potential of JOL2077 vaccine in broiler and young layer birds.

Determination of antimicrobial activity of some 1,2,4-triazole derivatives

We carried out MIC of the derivatives of 1,2,4-triazole II (4-((5-nitrofuran-2-yl)methyleneamino)-1-propyl-4H-1,2,4-triazolium bromide) and I (N-((5-nitrofuran-2-yl)methylene)-4H-4-amino-1,2,4-triazolidium chloride) against Escherichia coli ATCC 3912/4 and E. coli k88ad, Staphylococcus aureus ATCC 25923 and S. aureus k99, Klebsiella pneumonia k56 and Salmonella typhimurium 144, S. enteritidis. All test cultures were sensitive to compound II at concentrations of 1,25–0,039 μg/ml. Similar MIC (0,039 μg/ml) of compounds II and I were set for E. coli k88a and S. aureus k99 test cultures – 0,156 μg/ml. Only S. aureus ATCC 25923 and K. pneumonia k56 had sensitivity to ceftriaxone (MIC = 0,097 μg/ml). Antiviral activity of Trifuzol (piperidine 2-[5-(furan-2-il)-4-phenil-1,2,4-triazol-3-ilthio]acetate) and avistim (morpholines 3-(4-pyridyl)-1,2,4-triazolil-5-thioacetate) against the chicken infectious bronchitis virus (VIB) strain 4/91 was characterized by a decrease in mortality and pathological changes of chicken embryos (CE) which were induced by the virus. Death of infected CE provoked by the strain 4/91 of VIB in dilution 10–3 occurred at 57.1%. The reduction in the percentage of deaths of CE infected by the virus in dilution 10–3 in the presence of Avistim was 28.6%, and with Trifuzol 14.3%. The use of avistim and Trifuzol compounds reduced VIB infectious activity when it was cultivated in CE, reducing the titre of the virus (strain 4/91) by 3 lg EID 50 cm–3.

Recombinant live attenuated avian coronavirus vaccines with deletions in the accessory genes 3ab and/or 5ab protect against infectious bronchitis in chickens

Avian coronavirus infectious bronchitis virus (IBV) is a respiratory pathogen of chickens, causing severe economic losses in poultry industry worldwide. Live attenuated viruses are widely used in both the broiler and layer industry because of their efficacy and ability to be mass applied. Recently, we established a novel reverse genetics system based on targeted RNA recombination to manipulate the genome of IBV strain H52. Here we explore the possibilities to attenuate IBV in a rational way in order to generate safe and effective vaccines against virulent IBV (van Beurden et al., 2017). To this end, we deleted the nonessential group-specific accessory genes 3 and/or 5 in the IBV genome by targeted RNA recombination and selected the recombinant viruses in embryonated eggs. The resulting recombinant (r) rIBV-Δ3ab, rIBV-Δ5ab, and rIBV-Δ3ab5ab could be rescued and grew to the same virus titer as recombinant and wild type IBV strain H52. Thus, genes 3ab and 5ab are not essential for replication in ovo. When administered to one-day-old chickens, rIBV-Δ3ab, rIBV-Δ5ab, and rIBV-Δ3ab5ab showed reduced ciliostasis as compared to rIBV H52 and wild type H52, indicating that the accessory genes contribute to the pathogenicity of IBV. After homologous challenge with the virulent IBV strain M41, all vaccinated chickens were protected against disease based on reduced loss of ciliary movement in the trachea compared to the non-vaccinated but challenged controls. Taken together, deletion of accessory genes 3ab and/or 5ab in IBV resulted in mutant viruses with an attenuated phenotype and the ability to induce protection in chickens. Hence, targeted RNA recombination based on virulent IBV provides opportunities for the development of a next generation of rationally designed live attenuated IBV vaccines.

Immunological aspects of the efficiency of protectotype vaccination strategy against chicken infectious bronchitis.

BackgroundOne of the most commonly applied protectotype vaccination protocol against infectious bronchitis (IB) in broiler chickens in the EU is simultaneous or alternate use of Ma5 and 4/91 vaccine strains. After IB vaccination and infection, systemic and upper respiratory tract (URT), humoral and cell-mediated immunity (CMI), are stimulated. The level of this stimulation correlates with the level of protection against IB.ResultsWe’ve investigated the development of URT and systemic, cell-mediated and humoral immunity in commercial broiler chickens vaccinated with Ma5 and/or 4/91 strains at hatch day. We’ve demonstrated that the group vaccinated with Ma5 and 4/91 strain simultaneously developed the most desirable immunity which reflects the level of CD8+ T cells stimulation in spleen and Harderian gland, as well as the level of IgA and IgY in URT washings and serum and their cross-reactivity with 7 IBV strains.ConclusionsAlthough we did not demonstrate directly why Ma5 + 4/91 protocol is so efficient it seems that it combines the benefits of monovalent vaccination with either Ma5 or 4/91 and while Ma5 seems to stimulate CMI more efficiently, the 4/91 strain generates a wider spectrum of immune system cross-reactivity and higher URT IgA production.

Complete Genome Sequence of a Brazil-Type Avian coronavirus Detected in a Chicken.

Avian coronavirus is the causative agent of infectious bronchitis in chickens, leading to multisystemic disease that might be controlled if adequate vaccine strains are used. This paper reports the first complete genome sequence of a Brazil type of this virus (27,615 nucleotides [nt]) isolated from the kidneys of a chicken.

ІМУНОГІСТОХІМІЧНА ХАРАКТЕРИСТИКА СУБПОПУЛЯЦІЙ ЛІМФОЦИТІВ У СЕЛЕЗІНЦІ КУРЕЙ ПРИ ВАКЦИНАЦІЇ ЇХ ПРОТИ ІНФЕКЦІЙНОГО БРОНХІТУ

In the work the immunohistochemical characterization of subpopulations of СD4+, СD8+, CD45RA+ lymphocytes in the spleen of chickens vaccinated against infectious bronchitis clarified. Immunohistochemical studies have shown that changes in the clusters of immune cells after immunization was certain features in the spleen. Our studies showed that vaccination against infectious bronchitis of chickens in the first, 13 and 33, 83 and 103 day influenced on the change in the percentage of cells in the cluster of СD4+ (helper cells). So, after the introduction of the vaccine on the 8 th day, there was a tendency to increase to 9.23 ± 0,39% against 6,91 ± 0.26% in the control group. But at 20 days there was a significant increase in the number of helpers (of 10.07 ± 0,44% (p &lt; 0.01) against 8.51 ± 0.31% in the control. Early supresion manifestations were recorded on 8th day. There has been a dramatic increase in the number of СD8+ in the experimental group, where the number of cells with the marker were higher than in control more than in two times. So, when studying subpopulations of lymphocyte marker СD8+ installed content control for 9.88 ± 0.38% in Chicks which received the vaccine in this period, the number of СD8+ amounted to 24.99 ± 0,46% (p &lt; 0.001). On the 8th day there was a significant increase in the number of CD45RA+ to 14.22 ± 0.18% (p &lt; 0.001), in control group this indicator amounted to 9.95 ± 0.38% Maximum increase observed on the 40th day, when the CD45RA+ in the group immunized chickens amounted to 14.74 ± 0.29% (p &lt; 0.05).

Successive occurrence of recombinant infectious bronchitis virus strains in restricted area of Middle East.

Routine molecular diagnostic testing by our laboratory, based on using a primer pair with conservative binding sites on the spike glycoprotein coding sequence, has indicated the recurring of a unique phylogenetic cluster of chicken infectious bronchitis viruses (IBV) in the Middle East since 2010. The nearly full-length S1 subunit of the spike gene phylogeny of selected strains, however, split up this grouping, suggesting potential recombination in the S1 gene. In order to clarify this, various bioinformatic analyses of the strains were carried out, which confirmed this supposition. Two patterns of recombination were found among the strains, one of which could also be identified in GenBank-deposited IBV sequences from the region. These findings demonstrate that IBV strains of different recombinant patterns occur simultaneously in the same geographic region and could circulate for an extended period of time, thus contributing to the knowledge on IBV evolution.

Recombinant duck enteritis viruses expressing major structural proteins of the infectious bronchitis virus provide protection against infectious bronchitis in chickens

To design an alternative vaccine for control of infectious bronchitis in chickens, three recombinant duck enteritis viruses (rDEVs) expressing the N, S, or S1 protein of infectious bronchitis virus (IBV) were constructed using conventional homologous recombination methods, and were designated as rDEV-N, rDEV-S, and rDEV-S1, respectively. Chickens were divided into five vaccinated groups, which were each immunized with one of the rDEVs, covalent vaccination with rDEV-N & rDEV-S, or covalent vaccination with rDEV-N & rDEV-S1, and a control group. An antibody response against IBV was detectable and the ratio of CD4+/CD8+ T-lymphocytes decreased at 7 days post-vaccination in each vaccinated group, suggesting that humoral and cellular responses were elicited in each group as early as 7 days post-immunization. After challenge with a homologous virulent IBV strain at 21 days post-immunization, vaccinated groups showed significant differences in the percentage of birds with clinical signs, as compared to the control group (p < 0.01), as the two covalent-vaccination groups and the rDEV-S group provided better protection than the rDEV-N- or rDEV-S1-vaccinated group. There was less viral shedding in the rDEV-N & rDEV-S- (2/10) and rDEV-N & rDEV-S1- (2/10) vaccinated groups than the other three vaccinated groups. Based on the clinical signs, viral shedding, and mortality rates, rDEV-N & rDEV-S1 covalent vaccination conferred better protection than use of any of the single rDEVs.

Systemic and local immune mechanisms stimulated in the course of chicken infectious bronchitis

Infectious bronchitis (IB) is a highly contagious, viral disease of chickens that causes damage to the respiratory tract, kidneys, gastrointestinal and reproductive systems, as well as muscles. Despite the worldwide distribution of vaccines against IB, the outbreaks of this disease are recorded frequently. This review paper describes the mechanisms of the immune system response against both infectious bronchitis virus (IBV) and vaccine IBV, with special attention to the local upper respiratory tract immune mechanisms stimulated in the course of IB. CD8+ T cells as well as IgA+ and IgY+ B memory cells seem to play the most important role in protection against re-infection with IBV. The present paper describes in detail the stimulation of non-specific innate resistance factors and the underlying mechanism of IBV innate immunity breach, as well as the stimulation and acquisition of specificity and immune memory against IBV by immunocompetent cells after both infection and vaccination.

Survey indicates circulation of 4/91 and QX-type infectious bronchitis viruses in Hungary in 2014 - Short communication.

Understanding the epidemiology and improving vaccinal protection against the highly variable chicken infectious bronchitis virus (IBV) requires the knowledge of circulating IBV serotypes/genotypes in defined geographic areas. Accordingly, the authors initiated a survey among the major poultry producers in Hungary in order to reveal the prevailing IBV serotypes in the country. Tracheal swabs and organ samples (caecal tonsils, kidneys, and trachea) were collected from broiler, layer, and meat-type breeder flocks, and were subjected to IBV detection by virus isolation and polymerase chain reaction (PCR). The IBV-positive samples were further characterised by nucleotide sequencing and phylogenetic analysis of a portion of the S1 IBV gene. Seventeen out of the 26 submitted samples proved to be positive for IBV. Sequence analyses revealed ten 4/91 and six QX serotypes, and a single D274 type IB virus. One sample contained a mixture of QX and Massachusetts serotype viruses. Presumably most of the 4/91 and D274 type viruses were vaccine strains. The proportion of QX type viruses and their observed variation are in good agreement with the situation in a few other European countries. The detected viruses clustered largely according to their geographic origin, with a few exceptions. If updated regularly, the preliminary 'virus map' will be useful for the adjustment of vaccination protocols.

Novel Receptor Specificity of Avian Gammacoronaviruses That Cause Enteritis.

Viruses exploit molecules on the target membrane as receptors for attachment and entry into host cells. Thus, receptor expression patterns can define viral tissue tropism and might to some extent predict the susceptibility of a host to a particular virus. Previously, others and we have shown that respiratory pathogens of the genus Gammacoronavirus, including chicken infectious bronchitis virus (IBV), require specific α2,3-linked sialylated glycans for attachment and entry. Here, we studied determinants of binding of enterotropic avian gammacoronaviruses, including turkey coronavirus (TCoV), guineafowl coronavirus (GfCoV), and quail coronavirus (QCoV), which are evolutionarily distant from respiratory avian coronaviruses based on the viral attachment protein spike (S1). We profiled the binding of recombinantly expressed S1 proteins of TCoV, GfCoV, and QCoV to tissues of their respective hosts. Protein histochemistry showed that the tissue binding specificity of S1 proteins of turkey, quail, and guineafowl CoVs was limited to intestinal tissues of each particular host, in accordance with the reported pathogenicity of these viruses in vivo. Glycan array analyses revealed that, in contrast to the S1 protein of IBV, S1 proteins of enteric gammacoronaviruses recognize a unique set of nonsialylated type 2 poly-N-acetyl-lactosamines. Lectin histochemistry as well as tissue binding patterns of TCoV S1 further indicated that these complex N-glycans are prominently expressed on the intestinal tract of various avian species. In conclusion, our data demonstrate not only that enteric gammacoronaviruses recognize a novel glycan receptor but also that enterotropism may be correlated with the high specificity of spike proteins for such glycans expressed in the intestines of the avian host. Avian coronaviruses are economically important viruses for the poultry industry. While infectious bronchitis virus (IBV), a respiratory pathogen of chickens, is rather well known, other viruses of the genus Gammacoronavirus, including those causing enteric disease, are hardly studied. In turkey, guineafowl, and quail, coronaviruses have been reported to be the major causative agent of enteric diseases. Specifically, turkey coronavirus outbreaks have been reported in North America, Europe, and Australia for several decades. Recently, a gammacoronavirus was isolated from guineafowl with fulminating disease. To date, it is not clear why these avian coronaviruses are enteropathogenic, whereas other closely related avian coronaviruses like IBV cause respiratory disease. A comprehensive understanding of the tropism and pathogenicity of these viruses explained by their receptor specificity and receptor expression on tissues was therefore needed. Here, we identify a novel glycan receptor for enteric avian coronaviruses, which will further support the development of vaccines.

Emergence of Avian Infectious Bronchitis Virus and its Variants Need Better Diagnosis, Prevention and Control Strategies: A Global Perspective

Growth in poultry sector is being challenged due to increased incidence and re-emergence of diseases caused due to evolution of several viral pathogens and use of live vaccines. Piles of economic losses are encountered due to these diseases. Avian Infectious Bronchitis (IB), caused by Corona virus, is OIE-listed disease and characterized by respiratory, renal and urogenital involvements, causing high mortality. Economic losses are encountered due to loss of productive performance of both egg and meat-type chickens. Variant viruses evolve due to spontaneous mutations and recombinations, causing disease in vaccinated flocks of all ages. Serotyping and genotyping are the common methods of classification of IBV strains. The virus has 4 clusters, grouped into 7 serotypes and the most important strains are Massachusetts, Connecticut, Arkansas, Gray, Holte and Florida along with numerous others, distributed round the globe. Several conventional and molecular diagnostic methods have been described for the diagnosis of IB in chickens. 'All-in/all-out' operations of rearing along with good biosafety measures forms the basis of prevention, whereas vaccination forms the backbone of IB control programme. Both live and inactivated (oil emulsified) conventional vaccines are available. The new generation vaccines (recombinant and vector-based) developed against locally prevailing IBV strains may be more helpful and avoid the reversion of virulence in live vaccine viruses. The present review deals with all these perspectives of this important emerging poultry pathogen.