BRONQUITIS INFECCIOSA AVIAR PDF
English Translation, Synonyms, Definitions and Usage Examples of Spanish Word ‘virus de la bronquitis infecciosa aviar’. BRONQUITIS INFECCIOSA AVIAR. Recommended. Creative Insights: Renaldo Lawrence on Elearning. Online Course – LinkedIn Learning. Free Online Library: Genotipificacion de variantes del virus de bronquitis infecciosa aviar en el departamento del Tolima, Colombia.(ORIGINAL) by ” Revista MVZ.
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ABSTRACT In order to dissect the histopathological changes produced by the infection of avian infectious bronchitis virus in previously vaccinated egg-laying hens from a poultry farming unit, 35 White Leghorn egg-laying hens that had been in production for 9 to 10 months twenty seven of which had clinical symptoms corresponding to respiratory disease and eight apparently healthy individuals were selected for further study.
After clinical examination and necropsy, they were classified into apparently healthy, mild, moderate or severe according to the severity of the clinical-pathological process.
Samples were taken from paranasal sinuses, trachea and lungs for histopathological study, and trachea-lung pools were prepared from four individuals for virus isolation and molecular biology assays.
Histopathological analysis of the epithelia of paranasal sinuses, trachea and bronchia revealed the presence of epithelial erosion, mucous exudate and hyperplasia infeccosa mucosa-associated lymphoid tissue.
Glandular cysts were observed at the paranasal sinuses, and epithelial metaplasia was detected in the trachea. It was possible to isolate and identify infectious bronchitis infefciosa from the original samples and from samples passaged in chicken embryos.
WO2001009290A2 – Serotipo de virus de bronquitis infecciosa aviar – Google Patents
This situation is a consequence of, among other factors, the high potential for outbreaks of acute or chronic respiratory disease that characterizes intensive farming settings, with causative agents ranging from bacteria or avian mycoplasmas to pathogenic fungi or viruses [1, 2]. One prominent example of the latter case is that of avian infectious bronchitis virus Bronquitida gammacoronavirus belonging to the Coronaviridae family, in the order Nidovirales .
IBV is bfonquitis highly infectious virus with a geographic distribution spanning the entire world. Infections with this virus exact a heavy economic toll on the poultry industry, as they produce severe weight loss in layer flocks and decrease egg production and quality, ultimately raising rejection rates at downstream processing plants [4, 5]. The main clinical symptoms exhibited by laying hens affected by this virus include infecviosa conjunctivitis, dyspnea and, ultimately, asphyxia.
Although productivity usually rebounds after 4 to 5 weeks, previous production levels are seldom recovered. The affected eggs are usually deformed, whitish, porous, exhibiting calcareous excrescences or even lacking the shell in rare cases. Their albumen is orangey amber, and there is no distinction between aqueous and dense zones. During mild respiratory infections it is common to detect renal alterations such as inflammation and discoloration of kidneys, presence of urate salts at the ureters urolithiasis and visceral gout.
Nephropathogenic IBV pathotypes can cause this symptomatology . Among the anatomopathological characteristics of mild cases of respiratory disease are excessive mucus, which can even become sebaceous —especially in broilers— and pulmonary congestion and opacity, with aciar air avuar walls.
In severe cases there is also abundant mucus, producing severe inflammation with reddening of the tracheal rings in older chicken and asphyxia in younger individuals . Histologically, there is epithelial hyperplasia and metaplasia, as well as loss of cilia, in both trachea and bronchi, and superficial cells are often engrossed. Subepithelial engrossment zones are characterized by edema and infiltration of the lamina, mainly by monocytes and bronquittis .
The laboratory diagnosis of IBV requires isolating or directly detecting the virus, infeccosa serological techniques can be useful under some circumstances. Serotyping is done using hemagglutination inhibition assays, employing ELISA instead for serological diagnosis. Other techniques used for this purpose have included electron microscopy , assays based on monoclonal antibodies , viral neutralization assays  and, more recently, tests based on reverse transcriptase-polymerase chain reaction RT-PCR combined with restriction fragment length polymorphism to identify viral genotypes .
WOA2 – Serotipo de virus de bronquitis infecciosa aviar – Google Patents
The continuous appearance and emergence of new serotypes has complicated viral diagnosis and the design of effective control and management programs, as the resulting antigenic variation decreases the cross-protection afforded by vaccine strains against field strains of distantly related genotypes or serotypes .
Control of IBV in many countries is achieved mainly through a combination of biosafety procedures and live inrecciosa inactivated vaccines conferring a specific immune response . In Cuba there are immunization programs against avian infectious bronchitis based on the application of live and inactivated vaccines in breeder and layer flocks, respectively [18, 19]. Despite the implementation of control procedures and biosafety practices, however, outbreaks of respiratory syndrome with high morbility and low mortality have continued to affect intensive poultry farming facilities.
For the above reasons, it was decided to examine the histopathological changes caused by infections of the avian bronchitis virus in vaccinated egg-laying hens affected by chronic respiratory syndrome. They were fed a balanced diet, and their handling complied with current technical aviad and regulations of the country, in force since the decade of the s .
Immunization schedule The birds received three ijfecciosa of live vaccine strain H, Massachusetts serotype at 1, 35 and 85 days of life, following the immunization program currently infeciosa in the country . Gross examinations were performed avia necropsy, scoring the severity of clinical manifestations and recording existing anatomopathological lesions. The birds were then classified into four groups apparently healthy, mild, moderate and severe according to the severity of the clinical-anatomopathological alterations noticeable during gross examinations Table.
The paranasal sinuses samples were softened by placing them for 21 days in a decalcification solution. Organs for the virological and molecular study Trachea and lung fragments from three and four birds were taken and randomly pooled, per organ, in two groups of four and one of three from 11 birds in total. Quantification of epithelial glands at the trachea of animals with respiratory processes of varying severity This technique employed 35 tracheal rings from all 35 birds used in infcciosa study.
Gland atrophy was determined by histomorphometry of one ring from each trachea from animals falling into different levels of the chronic respiratory syndrome classification scale, based on the macroscopic clinical-anatomopathological characteristics described above. Viral isolation and molecular identification Samples of trachea and lungs from 11 hens in groups of three and four birds were taken after necropsy.
These samples were processed and stored at o C until inoculated into chicken embryos. Organ homogenates were inoculated into 9 to 11 lnfecciosa chicken embryos, injecting 0. At 72 h after inoculation, the allantoic fluid was collected, performing two to three blind passages in chicken embryos.
Vaccine strain H, used in the immunization program currently implemented in Cuba , was used as positive control. Statistical analysis The proportions of the principal histopathological lesions were compared, and a one-way analysis of variance Anova was performed to evaluate the loss of epithelial glands at the trachea, as implemented in the statistical software packages Comprop-1 and Statgraphics Plus 5.
RESULTS The main histological changes in paranasal sinuses, trachea and lungs of laying hens, grouped according to their score in classification scheme used during gross examinations, are shown in the table. The respiratory epithelium was markedly eroded, and there was degeneration of acinotubular glands. In individuals classified as severe there were glandular cysts with mucous exudation Figure 1.
Another important histopathological finding is the presence of hyperplastic acinotubular glands. The latter are totally full of mucus, and secrete their contents into the lumen with some degree of distension Figures 2A and Bas described in the table.
At the trachea there was moderate loss of cilia bronquits hyperplasia of the bronchus-associated lymphoid infecicosa BALT. In advanced stages of the respiratory infection there was also metaplasia of the cylindrical pseudostratified epithelium to flat cells, with submucosal engrossment Figures 2C and D. Histopathological analysis of the respiratory system also revealed changes in bronchi, such as BALT hyperplasia and a catarrhal exudative inflammatory response both in epithelial glands and the bronchial lumen Figures 2E and F.
Upon analysis of PAS-stained sections of the respiratory epithelium of paranasal sinuses, trachea and bronchi, it was possible to confirm the presence of catarrhal exudates mucous; figure 3.
There were statistically significant differences regarding the degree of epithelial gland loss in the tracheal rings of groups exhibiting the clinical-pathological alterations of chronic respiratory disease when compared to the control group, which had no apparent alterations. The bronuitis group severe exhibited the highest pathological significance Figure 4.
The viral isolation assays employing three successive passes in chicken embryos produced symptoms not unlike those of IBV when infecting adult individuals: Successful viral isolation was confirmed by RT-PCR analysis of clinical samples, which produced amplicons whose relative electrophoretic mobility bp matched that expected for the employed primers Figure 5.
Most strains of this virus are able to replicate in the upper respiratory tract without producing apparent clinical signs. When clinical signs are present, the progression of lesions in this system is divided in three stages: The severity of histopathological findings paralleled the scale based on clinical signs used to classify the groups with respiratory infection mild, moderate and severe. Some of the most conspicuous findings include the erosion of the epithelium with degenerative damage of paranasal sinus glands, BALT hyperplasia, and glandular hyperplasia with mucus hypersecretion throughout the respiratory epithelium with loss of cilia paranasal sinuses, trachea and primary bronchi.
The latter microscopic alterations, specifically those in the trachea, are defense mechanisms due to ciliary movement and the exudation of mucus by goblet cells during IBV infection .
These alterations, which characterize the acute stage of the disease, can be easily observed in the trachea by electron infeccipsa due to the anatomical simplicity of this organ . Virulent strains bronqquitis IBV produce epithelial damage, loss of cilia and hyperplasia. These effects predispose the individual to coinfections with opportunistic pathogens, such as Escherichia coli .
This enterobacterium often aggravates respiratory disease, leading in many cases to the death of infected bfonquitis . Another important histopathological finding is the presence of epithelial metaplasia, with characteristics resembling those of flat cells, and the engrossment of tracheal submucosa.
These results coincide with those of an earlier study published in . Controlling IBV infections through vaccination is difficult and not always successful, due to the continuous emergence of new viral serotypes and variants exhibiting very low levels of cross-protection [30, 31].
The origin nifecciosa this antigenic variation is multifactorial, and includes among its causes the selective immunological pressure exerted by the widespread application of vaccines, the high frequency of coinfections —leading to recombination events as an additional source of variation— and the disappearance of once avviar serotypes due to vaccination, followed infecckosa their replacement by different field strains [32, 33].
Many different IBV vaccines -mostly against variants of the Massachusetts strain- have been developed internationally, and their efficacy in broilers and laying hens has been well studied. Most of them, however, are prone to causing the disease themselves, and the protection they provide is poor or nil , as reported in for the DE [35, 36] and GA98 [37, 38] variants in the USA. Variants of the Massachusetts strains were also reported in Chile during the s , while the Dutch serotypes D, D, D and D have been described in Europe .
An IBV strain was isolated in in Africa and found to be responsible for severe respiratory problems [39, 44]. Additional Massachusetts strain variants were serotyped for Israel, during the mid s [13, 45, 46] and other IBV variants were described in Korea during the mid s .
Although a Massachusetts strain-based vaccine was used with good results in the latter case, its success was short-lived, as outbreaks of infectious bronchitis, with a high incidence brlnquitis renal complications, have been taking place since in vaccinated flocks from Korea.
One possible cause was uncovered by Lee et al. Some of these variants are indigenous, while others are genetically related to IBV variants in neighboring countries , suggesting that IBV strains in Korea are evolving continuously . In the case of Cuba, the results suggest that other, yet to be studied variants or serotypes of the Massachusetts strain may be currently circulating.
Risk of HBV infection is also influenced by other factors, such as complete or partial vaccine coverage failures, lower vaccine efficacy against heterologous strains, presence of immunosuppressive agents, inadequate immunization schedules, improper immunization technique, variations in immunization technique for instance, in the amount, quality and temperature of the water used to dilute the vaccine, or in the inoculated dose ; and the use of vaccine combinations against different agents [50, 51].
In this work, it bronnquitis possible to isolate and identify the IBV in hens, starting from the evaluation of histopathological findings in the respiratory system.
Some authors state that it is not always possible to identify IBV in flocks for several reasons. Although such hybrid or chimeric viruses will sometimes replicate better, the existence of differences in genetic regions is highly probable . Another possible cause is the movement of flocks and the mixing of layer hen batches, which together propitiate coinfections by unrelated strains and thus, the occurrence of recombination events between separate IBV lineages.
Summarizing, the present work described the histopathological changes in the epithelium of paranasal sinuses, trachea and bronchi of egg-laying hens affected by the infectious bronchitis coronavirus, as confirmed by viral isolation in chicken embryos and identification by RT-PCR. La calidad de la materia prima y el alimento terminado. Newcastle disease with special emphasis on its effect on village chickens. Food and Agriculture Organization of the United Nations; Experimental confirmation of recombination upstream bronquitsi the S1 hypervariable region of infectious bronchitis virus.
Cavanagh D, Gelb J. Nephropathogenic infectious bronchitis in Pennsylvania chickens Memorias Congreso Nacional de Avicultura; [cited Feb 16]. Enfermedades de las aves.
El Manual Moderno, Bronquitie. Detection of infectious bronchitis virus. Location of antigenic sites defined by neutralizing monoclonal antibodies on the S1 avian infectious bronchitis virus glycopolypeptide.
Identification of a novel nephropathogenic infectious bronchitis virus in Israel. Infectious bronchitis virus surveillance in Ontario commercial layer flocks. J Appl Poult Res. Vaccine efficacy against Ontario isolates of infectious bronchitis virus. Can J Vet Res.