Search Results (31)

Fowl adenovirus serotype 4 (FAdV-4) has been identified as the primary pathogen responsible for hydropericardium-hepatitis syndrome (HHS), resulting in significant economic losses in major poultry-producing countries since 2015. Timely and accurate diagnosis of FAdV-4 infection is essential for the effective prevention and control of HHS. In this study, the two nonstructural genes of FAdV-4, 100K and 22K, were inserted into the expression vector pET-32a (+) respectively. The expressed recombinant proteins were used as coating antigens to develop two indirect ELISA methods, designated as 100K-ELISA and 22K-ELISA. Both ELISAs demonstrated high specificity, showing no cross-reactivity with serum samples positive for other avian diseases. Both ELISAs yielded positive results when applied to 50 serum samples from SPF chickens experimentally infected with FAdV-4 and negative results when applied to 50 serum samples from SPF chickens immunized with an inactivated FAdV-4 vaccine. Similarly, the field sample testing results demonstrated a significant ability to distinguish between vaccinated and infected samples. The 100K-ELISA and 22K-ELISA, which are based on nonstructural proteins, may be effective tools for differentiating between FAdV-4 infection and vaccination, offering a promising approach for differentiating infected from vaccinated animals (DIVA) strategies in poultry. Full article

Fowl adenoviruses (FAdVs) represent a major threat to poultry health, with serotypes FAdV-1 and FAdV-4 causing adenoviral gizzard erosion (AGE) and hepatitis-hydropericardium syndrome (HHS), respectively. A wide variety of afflicted birds, including chicken, pigeon, and psittacine species, have been reported to carry aviadenoviruses. The disease is highly contagious and spreads rapidly between flocks and farms through vertical and horizontal transmission. In this study, we implemented a multi-stage computational drug-discovery pipeline to identify natural inhibitors of the viral fiber proteins for both FAdV-1 and FAdV-4. A curated library of 7523 natural compounds from the African Natural Products Database (ANPDB) and the South African Natural Compounds Database (SANCDB) was subjected to ADMET-based filtering, molecular docking, ADMET prediction, and 500 ns molecular dynamics simulations against four structural targets: Fiber-1 and Fiber-2 of FAdV-4, and the Short and Long Fibers of FAdV-1. Three ligands, ANPDB_6449 (−10.3 kcal/mol), ANPDB_2908 (−10.2 and −10.0 kcal/mol), and SANCDB_245 (−9.2 kcal/mol), consistently emerged as strong candidates across the entire computational workflow. While ANPDB_2908 demonstrated notable multi-target capability by binding to fiber proteins from both FAdV-1 and FAdV-4, ANPDB_6449 and SANCDB_245 exhibited strong serotype-specific potential, supported by stable interaction profiles and favorable drug-likeness characteristics. Together, these compounds highlight promising natural scaffolds for the development of targeted antiviral interventions against pathogenic FAdV serotypes. Full article

Fowl adenovirus serotype 4 (FAdV-4) is the major causative agent of hydropericardium-hepatitis syndrome (HHS), a disease responsible for considerable economic losses in poultry production. Although inactivated and live-attenuated vaccines reduce mortality, continued outbreaks highlight the need to optimize vaccination strategies. To address these limitations, we developed and evaluated a bivalent subunit vaccine composed of recombinant hexon-L1 and fiber-2 proteins, two major antigenic determinants associated with neutralization and pathogenicity. The proteins were expressed in Escherichia coli, purified under native conditions, confirmed for purity and antigenicity, and emulsified into a water-in-oil formulation. Chickens were immunized with either 10 μg or 20 μg doses, boosted after 14 days, and challenged with the homologous virulent FAdV-4 strain SDLC202009. The 20 μg dose conferred complete survival, eliminated histopathological lesions, prevented viral detection in tissues by PCR and immunohistochemistry, and fully blocked viral shedding. Similarly, the 10 μg dose induced a good protection with only minor pathological differences compared to the group treated with 20 μg. These results demonstrate that a bivalent hexon-L1 and fiber-2 subunit formulation elicits strong, dose-dependent humoral and tissue-level protection against homologous FAdV-4 challenge under the conditions tested. The experimental design did not include a monovalent fiber-2 comparator; therefore, conclusions regarding the relative contribution of each antigen are not drawn. Full article

Fowl adenoviruses are opportunistic emerging viruses that spread widely in fowls, infecting birds of all ages, including young broiler chicks. This study aims to genotype the current adenovirus strains associated with inclusion body hepatitis hydropericardium syndrome (IBH-HPS) among infected broilers in Upper Egypt and to evaluate their pathogenic features. In 2024, 100 tissue samples were collected across Assiut and Sohag governorates in Upper Egypt for genetic characterization and pathogenicity evaluation. FAdVs were detected in 22% (11/50) of flocks. Typical FAdV lesions of dead embryos were observed after seven days post egg inoculation. Regarding the PCR assay of the hexon gene, only 8 of 30 samples were confirmed positive at 897 bp, yielding a 26.6% positivity rate. The remaining samples were considered negative using established RT-qPCR protocols for other viral pathogens. Partial sequencing of the hexon gene revealed that FAdV isolates (n = 4) clustered within FAdV species-D serotype 2/11, as determined by phylogenetic analysis. The four isolates shared (98–99%) and (94–100%) nucleotide and amino-acid similarities to FAdV-D of Israeli strains (2019–2020) and contemporary Egyptian isolates (2022), respectively, and low genetic divergence (54–81%) in comparison with other documented species. The amino acid sequence alignment and 3D structure indicate that the four immunogenic HVRs are located in the L1 region of the hexon protein, and that the highly conserved ⁹¹GQMTT⁹⁵, a specific region for FAdV-D serotype 2/11, is present. Regarding pathogenicity, the gross and histopathological findings observed clearly demonstrate the systemic pathogenicity of FAdV-2/11 in the infected group, with a final mortality rate of 30% at seven days post-infection (dpi). The FAdV DNA in hepatic tissues and cloacal swabs was confirmed by the PCR method at 3 dpi and 5 dpi. These results emphasize the circulating of FAdV-2/11 species D in Upper Egypt and highlight the significant need for a single inactivated vaccine that effectively targets the relevant FAdV serotypes to achieve broader and more efficient protection. Full article

The widespread prevalence of different serotypes of fowl adenoviruses (FAdVs) has led to diverse vaccine demands, especially for subunit vaccines targeting FAdV-4 and FAdV-11, which cause hydropericardium-hepatitis syndrome (HHS) and inclusion body hepatitis (IBH), respectively. Although the Fiber protein is known to elicit robust immune protection, further exploration is needed to enhance the production of cross-neutralizing antibodies. This study utilized structural prediction and homology modeling techniques, employing domain-swapping strategy to integrate neutralizing epitope-containing amino acid sequences (274–451aa and 364–543aa) into the shaft domain of the Fiber protein. Two novel chimeric proteins were recombinantly expressed and developed into subunit vaccines: Fiber-C4/D11 and Fiber-D11/C4. Immunogenicity assessments revealed that the Fiber-C4/D11 vaccine group rapidly induced an antibody response against FAdV-11 within 7 days post-vaccination. By 28 days post-vaccination (dpv), the Fiber-C4/D11 vaccine group exhibited significantly higher levels of cross-neutralizing antibodies compared to the Fiber-D11/C4 group (p < 0.05). Challenge experiments demonstrated that both vaccines effectively alleviated clinical symptoms and prevented mortality in SPF chickens. Compared to Fiber-D11/C4, Fiber-C4/D11 significantly reduced body weight loss, liver lesions, viral titers in tissues, and viral shedding. Notably, no cross-neutralizing antibodies were detected following FAdV-4 or FAdV-11 infection, indicating a lack of natural cross-protection between the two serotypes. The chimeric vaccine addressed this gap, offering a promising multivalent approach to mitigate FAdV infections and advancing fowl adenoviral subunit vaccine strategies. Full article

Fowl adenovirus can cause various diseases such as hepatitis-hydropericardium syndrome (HHS) and inclusion body hepatitis (IBH), which leads to huge economic losses for China’s poultry industry. In recent years, the prevalence of FAdV-4, FAdV-8a, and FAdV-8b has been on the rise. In this study, a trivalent fowl adenovirus inactivated vaccine against FAdV-4/8a/8b was generated and the immune effect was evaluated. The results showed that chickens immunized with the trivalent vaccine could effectively resist the challenge of virulent strains of FAdV-4, FAdV-8a, and FAdV-8b. All chickens in the immunized groups survived after virus injection, gained weight normally, and the lesions in tissues and organs (liver, spleen, kidney, etc.) were significantly decreased compared with the control group. The viral load in the liver of the immunized group was significantly lower than that of the challenge control group five days after the challenge (p < 0.01), and the cloacal excretion was significantly lower than that of the non-immune control group (p < 0.01). Moreover, until 16 weeks after immunization, the neutralizing antibody level against FAdV-4, FAdV-8a, and FAdV-8b remained above 8.27 log2. As a result, the trivalent vaccine generated in our study was an attractive candidate to prevent and reduce the spread of HHS and IBH in China’s poultry industry. Full article

Fowl adenoviruses (FAdVs) are important emerging pathogens affecting the poultry industry in Egypt as they are the primary etiology of inclusion body hepatitis–hydropericardium syndrome (IBH-HPS) associated with severe economic losses. This study aims to identify the circulating FAdVs from cases of IBH-HPS in 5 Egyptian provinces during the period from October 2020 through September 2022. Out of the 210 examined flocks, liver samples from 66 flocks were positive for FAdVs (31.4%) using conventional polymerase chain reaction targeting loop 1 of the major hexon gene, with varying rates of mortality (1% to 14%). In the positive samples detected during the study, the histopathological examination revealed pathognomonic lesions of FAdVs, including basophilic and eosinophilic intra-nuclear inclusion bodies (INIBs). The percentage of FAdV positivity increased with the flock age; from samples collected at ages 1 to10, 11 to 20, 21 to 30, and >30 days of age, 10% (5/50), 25.6% (11/43), 34.3% (23/67), and 54% (27/50) were found positive for FAdVs, respectively. Notably, the positivity percentages among the flocks reared in cages were higher than for those reared in the deep litter system of housing. The gene sequencing and phylogenetic analysis of 19 strains revealed clustering into FAdV species D serotype 2/11, demonstrating that serotype 2/11 is most prevalent in the targeted Egyptian provinces during the period of the study. Several point mutations in the sequenced region among different strains were reported. These findings underscore the prevalence of FAdV and provide a basis for further research on circulating strains to develop effective control strategies. Full article

The concerns regarding Fowl Adenoviruses have gained significance in the poultry industry due to their association with various diseases, including Inclusion Body Hepatitis, Hepatitis-Hydropericardium Syndrome, and Adenoviral Gizzard Erosion (AGE). AGE is an emerging disease reported in several countries, particularly in Asia and Europe, causing significant economic losses in the poultry industry. In 2001, Fowl Adenovirus Serotype 1 was identified as the etiological agent of AGE in Japan. Since then, it has been spreading to other countries due to its transmission mode. Although Adenoviral Gizzard Erosion has been mostly described in broilers, it has also been observed in layers and pullets. This review offers a comprehensive analysis of Fowl Adenovirus Serotype 1, encompassing various key aspects of the virus. We also examine the pathogenesis and epidemiology of the virus, providing an overview of its distribution and prevalence in avian populations worldwide. Highlighting the most recent developments in serological and molecular techniques for virus detection, quantification, and genotyping and comparing them to conventional tests, this review aims to contribute to the understanding of the diagnostic workflow for this virus. Lastly, this review sheds light on some vaccine strategies to prevent Adenoviral Gizzard Erosion. Full article

Fowl adenovirus (FAdV) belongs to the Aviadenovirus genus within the Adenoviridae family. FAdVs are widely distributed and associated with various diseases in poultry, including adenoviral gizzard erosion (AGE), hepatitis-hydropericardium syndrome (HHS), and inclusion body hepatitis (IBH). In this study, we developed a multiplex conventional PCR for simultaneously detecting FAdV-4, -8b, and -11 by targeting the hexon gene. The multiplex PCR was optimized for primer concentrations and thermocycling conditions. The optimal primer concentration combination was set at 0.125 μM for FAdV-4, -8b, and 0.25 μM for FAdV-11. Under these conditions, the limit of detection (LOD) was 10³ copies/μL of plasmid standards for FAdV-4, -8b, and -11. These results demonstrated that the developed multiplex PCR method exhibits high specificity and sensitivity, with no observed cross-reactivity among these serotypes or with other poultry viruses. Therefore, this multiplex PCR will be an effective tool for accurate serotyping of FAdV-4, -8b, and -11, enabling more precise identification and differentiation of these three serotypes. Full article

Duck adenovirus Type 3 (DAdV-3) severely affects the health of ducks; however, its pathogenicity in chickens remains unknown. The objectives of this study were to evaluate the pathogenicity and major pathological changes caused by DAdV-3 in chickens. Viral DNA was extracted from the liver of the Muscovy duck, and the fiber-2 and hexon fragments of DAdV-3 were amplified through polymerase chain reaction (PCR). The evolutionary tree revealed that the isolated virus belonged to DAdV-3, and it was named HE-AN-2022. The mortality rate of chicks that received inoculation with DAdV-3 subcutaneously via the neck was 100%, while the mortality rate for eye–nose drop inoculation was correlated with the numbers of infection, with 26.7% of chicks dying as a result of exposure to multiple infections. The main symptoms exhibited prior to death were hepatitis–hydropericardium syndrome (HHS), ulceration of the glandular stomach, and a swollen bursa with petechial hemorrhages. A histopathological examination revealed swelling, necrosis, lymphocyte infiltration, and basophilic inclusion bodies in multiple organs. Meanwhile, the results of quantitative real-time PCR (qPCR) demonstrated that DAdV-3 could affect most of the organs in chickens, with the gizzard, glandular stomach, bursa, spleen, and liver being the most susceptible to infection. The surviving chicks had extremely high antibody levels. After the chickens were infected with DAdV-3 derived from Muscovy ducks, no amino acid mutation was observed in the major mutation regions of the virus, which were ORF19B, ORF66, and ORF67. On the basis of our findings, we concluded that DAdV-3 infection is possible in chickens, and that it causes classic HHS with ulceration of the glandular stomach and a swollen bursa with petechial hemorrhages, leading to high mortality in chickens. The major variation domains did not change in Muscovy ducks or in chickens after infection. This is the first study to report DAdV-3 in chickens, providing a new basis for preventing and controlling this virus. Full article

Fowl aviadenovirus (FAdV) is a member of the Aviadenovirus genus within the Adenoviridae family. FAdVs are divided into five species based on genomic differences: Fowl aviadenovirus A to Fowl aviadenovirus E (FAdV-A to FAdV-E). They are classified into twelve serotypes (FAdV-1 to FAdV-8a and FAdV-8b to FAdV-11) through cross-neutralization tests. FAdVs are mainly associated with hepatitis hydropericardium syndrome (HHS), adenoviral gizzard erosion (AGE), and inclusion body hepatitis (IBH). The serotypes commonly involved in IBH are FAdV-2, FAdV-11, FAdV-8a, and FAdV-8b. IBH causes significant economic losses in the poultry industry, mainly due to high mortality, reduced productivity, and immunosuppression. This is the first case report on IBH in Chile caused—according to post-mortem findings, molecular analysis, sequencing, and phylogenetic analysis—by FAdV-11. Since the serotype had not previously been reported in Chile, continued monitoring of IBH cases is required to determine the serotype of the circulating FAdVs and adapt preventative vaccination programs. Full article

Hepatitis-hydropericardium syndrome (HHS), caused by fowl adenovirus serotype 4 (FAdV-4), has been widely spread across China, resulting in great financial losses in the poultry industry. Therefore, efficient vaccines against this disease urgently need to be developed. In our study, the fiber-2 and penton base proteins derived from the FAdV-4 JS strain were expressed in a prokaryotic system (E. coli) in a soluble form. Then, the efficacy of the two recombinant proteins formulated with cheap and widely used adjuvants (Marcol™ 52 white oil) were respectively tested, and the minimum immune doses and safety of the above proteins were also determined. It was indicated that the fiber-2 (20 µg/bird, 200 µg/bird) and penton base (200 µg/bird) could provide complete protection against the highly pathogenic FAdV-4 and suppress its replication and shedding. Unfortunately, only the fiber-2 protein could induce complete protection (10/10) at a low dose (10 µg/bird). In addition, we confirmed that the fiber-2 subunit vaccine formulated with oil adjuvants was safe for vaccinated chickens. Conclusively, all of our results suggest that we successfully prepared an efficient and cheap fiber-2 subunit vaccine with few side effects. Full article

Hydropericardium hepatitis syndrome (HHS) is primarily caused by fowl adenovirus serotype 4 (FAdV-4), causing high mortality in chickens. Although vaccination strategies against FAdV-4 have been adopted, HHS still occurs sporadically. Furthermore, no effective drugs are available for controlling FAdV-4 infection. However, type I and III interferon (IFN) are crucial therapeutic agents against viral infection. The following experiments were conducted to investigate the inhibitory effect of chicken IFN against FadV-4. We expressed recombinant chicken type I IFN-α (ChIFN-α) and type III IFN-λ (ChIFN-λ) in Escherichia coli and systemically investigated their antiviral activity against FAdV-4 infection in Leghorn male hepatocellular (LMH) cells. ChIFN-α and ChIFN-λ dose dependently inhibited FAdV-4 replication in LMH cells. Compared with ChIFN-λ, ChIFN-α more significantly inhibited viral genome transcription but less significantly suppressed FAdV-4 release. ChIFN-α- and ChIFN-λ-induced IFN-stimulated gene (ISG) expression, such as PKR, ZAP, IRF7, MX1, Viperin, IFIT5, OASL, and IFI6, in LMH cells; however, ChIFN-α induced a stronger expression level than ChIFN-λ. Thus, our data revealed that ChIFN-α and ChIFN-λ might trigger different ISG expression levels, inhibiting FAdV-4 replication via different steps of the FAdV-4 lifecycle, which furthers the potential applications of IFN antiviral drugs in chickens. Full article

Adenovirus vectors possess a good safety profile, an extensive genome, a range of host cells, high viral yield, and the ability to elicit broad humoral and cellular immune responses. Adenovirus vectors are widely used in infectious disease research for future vaccine development and gene therapy. In this study, we obtained a fowl adenovirus serotype 4 (FAdV-4) isolate from sick chickens with hepatitis–hydropericardium syndrome (HHS) and conducted animal regression text to clarify biological pathology. We amplified the transfer vector and extracted viral genomic DNA from infected LMH cells, then recombined the mixtures via the Gibson assembly method in vitro and electroporated them into EZ10 competent cells to construct the FAdV-4 infectious clone. The infectious clones were successfully rescued in LMH cells within 15 days of transfection. The typical cytopathic effect (CPE) and propagation titer of FAdV-4 infectious clones were also similar to those for wild-type FAdV-4. To further construct the single-cycle adenovirus (SC-Ad) vector, we constructed SC-Ad vectors by deleting the gene for IIIa capsid cement protein. The FAdV4 infectious clone vector was introduced into the ccdB cm expression cassette to replace the IIIa gene using a λ-red homologous recombination technique, and then the ccdB cm expression cassette was excised by PmeI digestion and self-ligation to obtain the resulting plasmids as SC-Ad vectors. Full article

Fowl adenoviruses (FAdVs) are distributed worldwide in poultry and incriminated as the etiological agents for several health problems in fowls, and are capable of crossing species barriers between domestic and wild fowls. An FAdV strain was, for the first time, isolated from black-necked crane in this study, and was designated as serotype 4 Fowl aviadenovirus C (abbreviated as BNC2021) according to the phylogenetic analysis of its DNA polymerase and hexon gene. The viral genomic sequence analysis demonstrated that the isolate possessed the ORF deletions that are present in FAdV4 strains circulating in poultry fowls in China and the amino acid mutations associated with viral pathogenicity in the hexon and fiber 2 proteins. A viral challenge experiment with mallard ducks demonstrated systemic viral infection and horizontal transmission. BNC2021 induced the typical clinical signs of hepatitis–hydropericardium syndrome (HHS) with swelling and inflammation in multiple organs and showed significant viral replication in all eight organs tested in the virus-inoculated ducks and their contactees at 6 dpi. The findings highlight the importance of surveillance of FAdVs in wild birds. Full article