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| Histological examination of tissue samples from the chickens in different infection groups. (A1,B1,C1,D1) H&E staining of liver, kidney, lung, and spleen samples from the chickens infected with HN strain alone. (A2,B2,C2,D2) H&E staining of liver, kidney, lung, and spleen samples from the chickens infected with the AH720 strain alone. (A3,B3,C3,D3) H&E staining of liver, kidney, lung, and spleen samples from the chickens co-infected with HN and AH720 strains. (A4,B4,C4,D4) The normal tissue sample staining in the chickens of the PBS control.
Source publication
Fowl adenoviruses (FAdVs), which are distributed worldwide, have caused considerable economic losses to poultry farms. Co-infection with FAdVs and other avian pathogens has been reported previously. However, the pathogenicity of different serotypes of FAdVs causing co-infection remains unclear. Herein, strain HN from FAdV species C serotype 4 (FAdV...
Contexts in source publication
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... 3 days post-challenge, the liver, kidney, lung, and spleen tissues from the chickens in the four different groups were fixed for histopathological analysis. Pathological lesions were observed in various tissues of chickens in the different infection groups (Figure 3). The liver tissues from the chickens in group I showed severe liver lesions and presented typical basophilic inclusions with many infiltrating lymphocytes ( Figure 3A1). ...
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... liver tissues from the chickens in group I showed severe liver lesions and presented typical basophilic inclusions with many infiltrating lymphocytes ( Figure 3A1). Hepatocyte necrosis was found in the liver tissues of the chickens from group II ( Figure 3A2). Lymphocyte infiltration and hepatocyte necrosis were observed in the liver tissues of the chickens from group III (Figure 3A3). ...
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... necrosis was found in the liver tissues of the chickens from group II ( Figure 3A2). Lymphocyte infiltration and hepatocyte necrosis were observed in the liver tissues of the chickens from group III (Figure 3A3). No histological changes were observed in the livers of the chickens from the control group ( Figure 3A4). ...
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... infiltration and hepatocyte necrosis were observed in the liver tissues of the chickens from group III (Figure 3A3). No histological changes were observed in the livers of the chickens from the control group ( Figure 3A4). ...
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... renal hemorrhage was seen in the kidneys of the chickens from group I (Figure 3B1). No histological changes were observed in the kidneys of the chickens from the control group ( Figure 3B4). ...
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... disorder of the pulmonary bronchus, inflammatory exudation, and alveolar rupture were observed in the lung tissues from the chickens in group I (Figure 3C1). The lung tissues from the chickens in group II were relatively normal ( Figure 3C2). Desquamation of pulmonary epithelial cells was observed in the lung tissues from the chickens in group III (Figure 3C3). ...
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... lung tissues from the chickens in group II were relatively normal ( Figure 3C2). Desquamation of pulmonary epithelial cells was observed in the lung tissues from the chickens in group III (Figure 3C3). No significant histological changes were observed in the lung tissues from the chickens in the control group ( Figure 3C4). ...
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... of pulmonary epithelial cells was observed in the lung tissues from the chickens in group III (Figure 3C3). No significant histological changes were observed in the lung tissues from the chickens in the control group ( Figure 3C4). ...
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... number of lymphocytes was reduced in the spleen tissues from the chickens in group I (Figure 3D1). Splenic hemorrhage was observed in the spleen tissues from the chickens in group II ( Figure 3D2). Splenic hemorrhage and reduced lymphocytes were observed in the spleen tissues from the chickens in group III ( Figure 3D3). ...
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... hemorrhage was observed in the spleen tissues from the chickens in group II ( Figure 3D2). Splenic hemorrhage and reduced lymphocytes were observed in the spleen tissues from the chickens in group III ( Figure 3D3). No significant histological changes were in the spleen tissues from the chickens in the control group ( Figure 3D4). ...
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... hemorrhage and reduced lymphocytes were observed in the spleen tissues from the chickens in group III ( Figure 3D3). No significant histological changes were in the spleen tissues from the chickens in the control group ( Figure 3D4). ...
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... the histopathological features of tissues of the liver, kidney, lung, and spleen were investigated. Histopathology lesions were observed in all the sampled tissues of the chickens from different infection groups compared with that of the chickens from the control group (Figure 3). Among these, liver tissues of chickens showed the most severe lesions. ...
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... these, liver tissues of chickens showed the most severe lesions. Notably, hepatocyte accumulation in the liver was observed in the chickens from group III (Figure 3). This is consistent with the results of the IFA analysis, which showed that the HN strain presented a scattered localization, whereas the AH720 strain presented an accumulated localization in the livers of the chickens from group III (Figure 5). ...
Citations
... Fowl adenovirus (FAdV) serotype 8b belongs to Group E of the genus aviadenovirus in the family Adenoviridae [1,2] and is an etiologic agent of inclusion body hepatitis (IBH) in broiler chickens that are 3-7 weeks of age and cause mortality of 2%-30% [3][4][5]. IBH pathogenesis may involve sudden death with no obvious clinical signs [6]. ...
Background and Aim
Live-attenuated vaccines are the most successful type of vaccine and could be useful in controlling fowl adenovirus (FAdV) 8b infection. This study aimed to attenuate, molecularly characterize, and determine the immunogenicity, efficacy, and challenge virus shedding in broiler chickens.
Materials and Methods
The FAdV 8b isolate (UPM08136) was passaged onto chicken embryo liver (CEL) cells until attenuation. We sequenced and analyzed the hexon and fiber genes of the passage isolates. The attenuated bioreactor-passage isolate was inoculated into 1-day-old broiler chickens with (attenuated and inactivated) and without booster groups and challenged. Body weight (BW), liver weight (LW), liver: body weight ratio (LBR), FAdV antibody titers, T-lymphocyte subpopulation in the liver, spleen, and thymus, and challenge virus load and shedding were measured.
Results
Typical cytopathic effects with novel genetic changes on CEL cells were observed. The uninoculated control-challenged (UCC) group had significantly lower BW and higher LW and LBR than the inoculated groups. A significantly higher FAdV antibody titer was observed in the challenged non-booster and attenuated booster groups than in the UCC group. T cells in the spleen and thymus of the liver of inoculated chickens were higher than uninoculated control group levels at all-time points and at different times. A significantly higher FAdV challenge virus load was observed in the liver and shedding in the cloaca of UCC chickens than in non-booster chickens.
Conclusion
The FAdV 8b isolate was successfully attenuated, safe, and immunogenic. It reduces virus shedding and is effective and recommended as a vaccine against FAdV infection in broiler chickens.
... Notably, Chen et al. isolated 155 FAdV strains from diseased chickens between 2015 and 2018 and found that 79.4% (123 out of 155) and 13.5% (21 out of 155) of these isolates were identified as FAdV-4 and FAdV-8a, respectively (11), indicating that there is an increasing trend of FAdV-8a infection. The infection of FAdV-8a alone cannot cause severe disease (12)(13)(14); however, the outcome may become complicated when co-infected with other pathogens or other serotypes of fowl adenoviruses (14,15), which raises concerns for the prevention of FAdV-8a. ...
... Notably, Chen et al. isolated 155 FAdV strains from diseased chickens between 2015 and 2018 and found that 79.4% (123 out of 155) and 13.5% (21 out of 155) of these isolates were identified as FAdV-4 and FAdV-8a, respectively (11), indicating that there is an increasing trend of FAdV-8a infection. The infection of FAdV-8a alone cannot cause severe disease (12)(13)(14); however, the outcome may become complicated when co-infected with other pathogens or other serotypes of fowl adenoviruses (14,15), which raises concerns for the prevention of FAdV-8a. ...
Recently, the infection of fowl adenoviruses (FAdVs) in chicken flocks has caused huge economic losses to the poultry industry in China. Although immunization with Fiber protein can provide autogenous protection of FAdVs, no commercial multivalent vaccines are available for the prevention and control of FAdVs. In this study, a novel recombinant virus FAdV4-F/8a-rF2 expressing the Fiber of FAdV-8a was generated through CRISPR-Cas9 and Cre-LoxP system by using the template virus FA4-EGFP. FAdV4-F/8a-rF2 not only exhibited a similar replication capacity to the wild-type FAdV-4 in Leghorn male hepatoma (LMH) cells but was also highly attenuated to specific pathogen free (SPF) chickens. Moreover, the inoculation of FAdV4-F/8a-rF2 could induce high neutralizing antibodies and provide full protection against both FAdV-4 and FAdV-8a. All these data demonstrate that the recombinant virus FAdV4-F/8a-rF2 developed here can be used as an attenuated bivalent vaccine candidate for the prevention and control of both FAdV-4 and FAdV-8a.
IMPORTANCE
Epidemiological data reveal that FAdV-4 and FAdV-8a are the dominant serotypes of FAdVs in the poultry industry in China. Although three commercial inactivated vaccines against FAdV-4 have been licensed in China, the bivalent vaccine against both FAdV-4 and FAdV-8a is not available. Here, we used CRISPR-Cas9 and Cre-LoxP system to generate a recombinant virus FAdV4-F/8a-rF2 expressing the Fiber of FAdV-8a. Notably, FAdV4-F/8a-rF2 was highly attenuated and could provide efficient protection against both FAdV-4 and FAdV-8a in the chicken infection model, highlighting the applaudable application of FAdV4-F/8a-rF2 as a novel live-attenuated bivalent vaccine against the diseases caused by the infection of FAdV-4 and FAdV-8a.
... On the other hand, the birds analyzed in this study were not vaccinated, so it can be deduced that the viral strains that are present in commercial batches are field strains. Many studies showed that the genotypes characterized here were associated with outbreaks of IBH or HHS in chickens in several countries around the world [41,[46][47][48]; however, the vast majority of reports of IBH or HHS worldwide have been associated with FAdV-4/C1 [23,[49][50][51][52] and the report of a large number of outbreaks associated with this FAdV genotype has led many studies to focus on the development of vaccines based on this viral genotype [53][54][55], as well as associations with other genotypes (FAdV-8b/E3) where excellent protection against infections with both genotypes is shown [1,12,[56][57][58]. However, these recombinant vaccines have not been tested with other FAdV genotypes that are included in the same group to which the vaccine strains belong, in the case of FAdV-8b/E3 belonging to species E, perhaps it could generate protection against FAdV-8a/E2 and FAdV-6/E1 strains and be an alternative in the country. ...
Fowl adenoviruses are a group of pathogens that cause large economic losses worldwide in the poultry industry, in addition to producing a wide range of diseases, such as IBH, HHS, and enteric and respiratory diseases. The objective of this study was to quantify, identify, and molecularly characterize the types of FAdV circulating in commercial poultry farms (broilers, breeders, and layers) in Ecuador from 2019 to 2021. Molecular characterization was performed by PCR, quantification by qPCR, and subsequent sequencing for each positive sample. The results indicated that the FAdV genotypes circulating in our country are FAdV-2/D2, FAdV-6/E1, FAdV-8a/E2, and FAdV-11/D3; the samples were grouped into different groups that contain sequences that were obtained from countries in Africa, Asia, and America, and that are found in birds at different ages, since early age where can cause different clinical signs, such as diarrhea, ruffled feathers and dwarfism. Therefore, these results indicate that several genotypes of the virus are circulating in commercial poultry flocks, suggesting that biosecurity measures on farms should be improved, in addition to carrying out new or improved vaccination plans.
... Hence, this coinfection was not due to contamination and laboratory originated. In a recent study, Liu et al. [43] showed coinfection with FAdV serotypes 4 and 8b. Tey reported similar clinical symptoms, mortality rates and degree of tissue lesions in coinfected birds as in single infection with serotype 4. ...
Background. The livestock sector contributes 1.90% to the GDP in Bangladesh during 2021–22. Poultry is one of the important subsectors struggling with diseases. Fowl adenoviruses (FAdVs) cause numerous diseases resulting in economic losses to the poultry industry worldwide. Several FAdV serotypes cause inclusion body hepatitis in chicken. Although FAdV infection was suspected, there was no confirmatory report from Bangladesh. The study was conducted to investigate the FAdV infection and antibodies in chicken. Methods. A total of 50 samples, each composed of liver and spleen, were collected from different chickens of Gazipur, Dinajpur, and Panchagarh district. Each location belongs to A, B, and C poultry zones of Bangladesh, respectively. Viruses were detected by real-time PCR and conventional PCR. Blood samples (n = 303) were collected at the beginning and after the recovery from infection and tested by indirect ELISA. Sequencing of PCR products was done for serotyping and phylogenetic analysis. Results. Clinical signs were observed including anorexia, drowsiness, ruffled feathers, reduced body weight, lack of uniformity, and high mortality (15–25%). Enlarged friable liver with yellow to tan color mottled with the focal soft area, fluid in pericardial sac, swollen and hemorrhagic kidneys, enlarged congested spleen and pancreas, etc. were found on postmortem examination. FAdVs were detected in 90% of the flocks except commercial layer flock from Dinajpur. Three serotypes, namely, 8b (70%), 11 (10%), and 5 (10%) were detected. Anti-FAdV antibody was detected in 80% flocks at the beginning of infection and in 90% of the flocks after recovery from infection. The antibody titer increases significantly (p
... Finally, this study concentrated on the fowl adenovirus infections only, even though concurrent diseases have been reported (Toro et al., 2000;Mei et al., 2020). It is also important to note that simultaneous infections with multiple strains of fowl adenovirus can enhance the viral replication capacity of strains and increase the viral load (Liu et al., 2021). Notwithstanding, the outcomes of this study may provide valuable information for the further investigation of the fowl adenoviruses in the same geography. ...
Fowl adenoviruses (FAdVs) have a worldwide distribution in poultry at all ages and the incidence of the disease has been in an increasing trend in the last decade. Most of the studies had revealed the status quo of disease in commercial chickens, especially in broilers; however, there was not sufficient data to estimate in backyards. Thus, the primary goal of this study was to investigate the presence of infections in backyard poultry operations. For this purpose, 389 internal organ samples were collected from 56 flocks from clinically suspected backyard chickens at 10 to 35-week-age. Samples were tested by the PCR method targeting the nucleotide sequences of hexon genes (A-D). Amplified genes were sequenced by the Sanger sequencing method and the elicited data were further used for the phylogenetic analyses. Of the 389 samples, 23.9% were found to be FAdV positive which was equal to 17 out of 56 flocks sampled for this study. This is the first study being carried out in backyard operations and two species (Fowl adenovirus D and Fowl adenovirus C) and four serotypes (FAdV-8a, FAdV-3, FAdV-4, and FAdV-10) have been discovered for the first time in Turkey. As a result, the outcomes of this study provide a better understanding of the epidemiology of FAdV in Turkey; hence, will aid in creating a robust control and prevention strategy.
... Moreover, pulmonary histopathological lesions characterized by congestion of numerous blood vessels and acute bronchopneumonia similar results were documented by [44] who detected that structural disorder of the pulmonary bronchus, inflammatory exudation, and alveolar rupture in infected birds. ...
Background
Over the past 10 years, inclusion body hepatitis outbreaks, essentially from commercial broiler flocks, have been detected in different geographic regions highlighting the wide distribution of FAdVs around the world resulting in serious economic losses due to increased mortalities as well as poor performance within poultry farms in Assiut province, Egypt. Thus, this study was achieved to detect fowl adenovirus in broiler chicken flocks in Assiut province, Egypt and to recognize the pathogenicity of the isolated virus.
Results
The phylogeny of the L1 loop of the hexon gene exposed that the isolated virus clustered and belonged to the reference strains serotype D FAdV. The isolated virus is closely related to inclusion body hepatitis (IBH) strains causing extensive economic losses. The pathogenicity study of the virus showed typical macroscopic lesions with 6% mortality; furthermore, histopathological inspection exhibited severe hepatitis and degenerative changes after 5d from infection in the immune system.
Conclusion
Results in this research support the primary pathogenicity and mortality caused by FADV serotype 2 (IBH) alone without immunosuppressive agents thus robust control measures should be implanted against FAdV to evade the serious economic losses in poultry farms.
... The novel genotype FAdV-4 spread rapidly and induced a 30-100% mortality rate, causing huge economic losses and threatening the green and healthy poultry breeding industry. Furthermore, co-infections of FAdV-4 with other virus further aggravate the harmfulness of the disease (18)(19)(20). ...
Fowl adenovirus (FAdV) was first reported in Angara Goth, Pakistan, in 1987. For this reason, it is also known as “Angara disease.” It was later reported in China, Japan, South Korea, India, the United States, Canada, and other countries and regions, causing huge economic losses in the poultry industry worldwide. Notably, since June 2015, a natural outbreak of severe hydropericardium hepatitis syndrome (HHS), associated with a hypervirulent novel genotype FAdV-4 infection, has emerged in most provinces of China. The novel virus FAdV-4 spread rapidly and induced a 30-100% mortality rate, causing huge economic losses and threatening the green and healthy poultry breeding industry. Vaccines against FAdV-4, especially the emerging novel genotype, play a critical role and will be the most efficient tool for preventing and controlling HHS. Various types of FAdV-4 vaccines have been developed and evaluated, such as inactivated, live-attenuated, subunit, and combined vaccines. They have made great contributions to the control of HHS, but the details of cross-protection within FAdVs and the immunogenicity of different vaccines require further investigation. This review highlights the recent advances in developing the FAdV-4 vaccine and promising new vaccines for future research.
In recent years, fowl adenovirus (FAdV) transmission has significantly increased worldwide, leading to substantial economic losses in the poultry industry. The virus causes hepatitis-hydropericardium syndrome (HHS) and inclusion body hepatitis (IBH). The prevalent FAdV strains in China are FAdV-4, FAdV-8a, FAdV-8b, and FAdV-11. Vaccines for FAdV-4 and FAdV-8b, which prevent HHS and IBH, are available commercially, but no vaccine exists for FAdV-8a. To address this issue, we developed a vaccine using an oil emulsion to inactivate the FAdV-8a serotype. Additionally, we built a fluorescence quantitative PCR for the detection of the virus. The lowest concentration detected was 4.11 × 10¹ copies/μL. The study's results illustrated that the FAdV-8a oil emulsion vaccine effectively produced significant antibodies and offered ample protection for poultry. This vaccine can potentially limit the transmission of IBH resulting from FAdV-8a in China.
