Fowl adenovirus strains 1/A and 11/D isolated from birds with reovirus infection

Whole genome sequence analysis of turkey orthoreovirus isolates reveals a strong viral host-specificity and naturally occurring co-infections in commercial turkeys

Avian orthoreoviruses (ARV) are an emerging threat for the poultry industry, both in the United States (US) and globally. ARV infections in turkeys have been associated with arthritis, lameness and neurological disorders, and cost the US economy approximately USD 33 million per year. There is not a commercial vaccine available and the shortage of turkey ARV (TRV) genomic data hinders the efforts to explore the molecular epidemiology of this virus, although several studies suggest a close relationship between European TRVs and TRVs present in the US. This study shows a snapshot of the genomic diversity of Avian orthoreoviruses (ARV) circulating in Germany in the mid-2000s. Through a deep genomic analysis of 18 ARV isolates recovered from sick turkeys, we observed that co-infection was a common condition. 80% of the samples showed signs of a simultaneous infection with a TRV and a chicken ARV (CRV). We believe this is the first reported evidence of CRV and TRV naturally occurring co-infections in commercial turkeys. These co-infection events were identified due to the significant genomic diversity observed among ARV infecting various production bird species. Our phylogenetic analysis revealed a consistent host-associated ARV clustering, with three main clades: (i) a TRV clade, (ii) a CRV clade, and (iii) a Duck ARV (DRV)/Goose ARV (GRV) clade. Furthermore, our findings indicate that German TRVs have interacted with their European and American counterparts, suggesting active mobilization of the virus, likely through the commercial trading of live animals. However, we also consider the potential role of migratory birds in the international movement of ARV.

Isolation and molecular characterization of fowl adenovirus from inclusion body hepatitis cases in Western India during 2019-2021

Background

Inclusion body hepatitis (IBH) resulted in a substantial economic loss in Western India during 2019 to 2021.

Aims

The study aimed to characterize fowl adenovirus (FAdV) from field outbreaks.

Methods

The study was conducted on 290 liver samples from 66 poultry flocks. The samples were subjected to histopathology and molecular detection, followed by phylogenetic typing of the partial hexon gene of the virus.

Results

Spiking mortality (14%) was recorded from day 21 to day 35 with peak mortality at the 28th day of age. The necropsy showed a pale and enlarged liver with hemorrhagic and yellowish necrotic foci, accumulation of straw-colored transudate in the pericardial sac which resulted in a flabby appearance of the heart, heart enlargement, and hemorrhages on the spleen, enlarged and congested kidneys. The virus inoculation resulted in stunting and poor feathering with hepatomegaly, hemorrhages and yellowish necrotic foci on the liver as well as greenish discoloration, and kidney swelling in SPF embryonated chicken eggs. Out of 29, 16 liver samples yielded 1219 bp amplicons specific to hexon gene fragments. The sequence and phylogenetic analysis identified 14 isolates as FAdV species E serotype 11 and two as species D serotype 8b. Conclusion: The results indicated that FAdV-8b and FAdV-11 strains are involved in disease outbreaks in western India.

Fowl Adenovirus Infection – Potential Cause of a Suppressed Humoral Immune Response of Broilers to Newcastle Disease Vaccination

Fowl adenovirus infections have a significant economic impact, especially in the production of broilers. It is considered the leading cause of three syndromes: adenoviral gizzard erosions and ulcerations, inclusion body hepatitis, and hepatitis-hydropericardium syndrome. A critical feature of this virus is its immunosuppressive effect, via suppressing humoral and cellular immunity.

In this study, we examined the humoral immune response after administration of the Newcastle disease vaccine in broiler flocks with previously confirmed seroconversion against Fowl adenovirus. The study was conducted on 5 farms. A total of 220 chickens, five weeks of age, showing no clinical signs of the disease, were included in this study. The control group consisted of 20 chickens from a negative farm. Chickens were vaccinated with commercially available live NDV vaccines between 11 and 13 days of life. ELISA determined the presence of specific antibodies against FAdV in a total of 130/200 (65%) blood sera. Depending on the farm, seroprevalence ranged from 30-100%. The presence of specific antibodies against NDV was determined three weeks after vaccination using the hemagglutination inhibition assay. A positive hemagglutination inhibition (HI) titer (≥ 16) was found in 41/200 (20.5%) sera, which was significantly less compared to the control farm, where a positive HI titer was found in 20/20 (100%) sera.

The results of our study indicate the immunosuppressive effect of FAdV in subclinically infected birds and highlight the need for its diagnosis, prevention, and control.

Molecular phylodynamics of fowl adenovirus serotype 11 and 8b from inclusion body hepatitis outbreaks

Fowl adenovirus (FAdV) serotypes are involved in a variety of clinical manifestations in poultry and has resulted in substantial economic loss to the poultry farmers. Despite the endemicity of Inclusion body hepatitis (IBH) in South Asian countries, including India, its etiology is not well studied. In western India, the rural poultry flocks obtained from the vaccinated parents were experiencing disease outbreaks with substantial economic losses due to heavy outbreaks and mortality. Therefore, the study was conducted to decipher the molecular epidemiology of the FAdV from field outbreaks in western India. A total of 37 commercial broiler poultry flocks and 29 village poultry flocks of western India were visited during 2019 to 2021. Out of these, 19.14% flocks showed incidence of IBH during the age of 15 to 35 days. The mortality ranged from 3.3 percent to 55.28 percent. The samples were subjected for amplification of partial hexon gene covering loop 1 and loop 2. The results revealed 48.28% positivity by PCR. The sequence analysis identified 14 isolates as species D serotype 11 with 0.97 to 0.99% divergence and two as species E serotype 8b with 0.99% divergence. The FAdV-11 isolates showed amino acid substitutions D195N, T399A, N417S, and N496H. The amino acids I188 and N195 were conserved in FAdV-11. The molecular clock in Bayesian methods was used to determine most common ancestor. The isolates MH379249 and MH379248 were determined the most recent common ancestor for FAdV-11 and FAdV-8b isolates. The analysis suggested evolution of 10 FAdV-11 strains in 2012, and four FAdV-11 strains and two FAdV-8b strains in 2018.

Current epidemiological situation in the context of inclusion body hepatitis in poultry flocks in Poland

The research has been undertaken to understand the spreading of adenovirus strains in Poland's poultry flocks in the last six years. One hundred and forty-nine herds suspected of infection with adenoviruses were tested and the presence of poultry adenoviruses was found in 86 studied herds which were about 57,71% of examined flocks. Thirty-eight (44.18%) strains were connected with the infection of inclusion body hepatitis, 11 (12.79%) strains were isolated from digestive system dysfunction, 33 (38.37%) strains had been obtained from the flocks with no symptomatic changes/behaviour, and four (4.65%) strains were obtained from flocks with the manifestation of depression. Sequencing analysis was based on Loop L1 region of the HVR1-4 fragment of the hexon gene. The adenovirus strains were classified into five species FAdV-A-E, belonging to the following eight serotypes: FAdV-1/A, FAdV-5/B, FAdV-3/10/C, FAdV-9/11/D, and FAdV-7/8a/E. The most common serotype in poultry turned out to be type/species FAdV-11/D, FAdV-5/B, and FAdV-7/8b/E while the least frequent was type/species FAdV-3/10/C (only four and two strains respectively of this types were isolated with the following range: FAdV-1/A 6 (6.97%), FAdV-5/B 24 (27,90%), FAdV-3/C 4 (4,65%), FAdV-10/C 2 (2,32%), FAdV-11/D 36 (41,86%), and FAdV-E 14 (16.27%). The understanding of genetic diversity, geographic distribution, and antigenic properties of fowl adenovirus strains (FAdVs) isolated in Poland have been evaluated.

Epidemiological and molecular analysis of circulating fowl adenoviruses and emerging of serotypes 1, 3, and 8b in Egypt

Fowl adenoviruses (FAdVs) are a large group of viruses of different serotypes. They are responsible for inclusion body hepatitis, adenoviral gizzard erosion, and hepatitis hydropericardium syndrome. The present study presents a comprehensive overview of FAdVs in Egypt, with a focus on the epidemiological features of virus serotypes across the country. We conducted molecular investigation of multiple FAdV species based on the genetic signature of hypervariable regions 1–4 in the loop1 (L1) region of the hexon gene. Epidemiologically, the Nile Delta governorates showed high positivity of FAdVs, which were more commonly found in broilers than in layers. Genetically, species D and serotype 8a/E dominated, and the findings also revealed the emergence of new FAdV serotypes 1, 3, and 8b. The comparative analysis of hypervariable regions in the L1 region of the hexon gene revealed variables specific to each virus serotype. In silico predictions of L1 region revealed variations in the molecular structure and predicted the antigenic epitopes which may affect the cross-antigenicity between the different FAdV species and serotypes.

Pathogenicity of field strain of fowl aviadenovirus serotype 11 isolated from chickens with inclusion body hepatitis in Morocco

Outbreaks of inclusion body hepatitis have emerged in Morocco since 2013 and has resulted in significant economic losses to poultry farms. Three isolates of the causative virus, Fowl adenonovirus (FAdV)were characterized from chickens with IBH, but their pathogenicity has never been investigated. In this work, the pathogenicity of an isolate FAdV 11 (MOR300315 strain) was evaluated by inoculating a group of 40 SPF chickens at 3 days of age by oral route. A group of 40 chicks injected with phosphate-buffered saline solution was used as a control group. The infected chickens showed decreased weight gain from 3dpi. Necropsy displayed pallor and enlargement in liver, swelling and slight hemorrhage in kidney and spleen at 6 dpi. Histopathological changes were mainly characterized by severe and extensive hepatic necrosis associated with the presence of basophilic intra-nuclear inclusion bodies within hepatocytes. The FAdV was reisolated in chicken embryo fibroblast cell culture from liver tissue homogenate of infected chicken from 3 to 6 dpi. Viral DNA was detected by PCR in liver, kidney, spleen and cloacal swabs from 3 to 13 dpi. Antibody response against inoculated FAdV was appeared from 9 dpi. These results confirmed that the FAdV 11 strain is pathogenic in chicken. This study is the first experimental infection of FAdV 11 in chicken in Morocco, which increase our understanding of its pathogenicity in chickens and indicate that preventive measures against FAdV infection in poultry farms should be implemented in Morocco.

Historical Investigation of Fowl Adenovirus Outbreaks in South Korea from 2007 to 2021: A Comprehensive Review

Fowl adenoviruses (FAdVs) have long been recognized as critical viral pathogens within the poultry industry, associated with severe economic implications worldwide. This specific group of viruses is responsible for a broad spectrum of diseases in birds, and an increasing occurrence of outbreaks was observed in the last ten years. Since their first discovery forty years ago in South Korea, twelve antigenically distinct serotypes of fowl adenoviruses have been described. This comprehensive review covers the history of fowl adenovirus outbreaks in South Korea and updates the current epidemiological landscape of serotype diversity and replacement as well as challenges in developing effective broadly protective vaccines. In addition, transitions in the prevalence of dominant fowl adenovirus serotypes from 2007 to 2021, alongside the history of intervention strategies, are brought into focus. Finally, future aspects are also discussed.