High incidence of glomerulonephritis associated with inclusion body hepatitis in broiler chickens: routine histopathology and histomorphometric studies

Evaluation of different heterologous-homologous vaccine regimens against challenge with GI-23 lineage infectious bronchitis virus

This study assesses different IBV vaccination regimens in broiler chickens using commercially available live attenuated GI-23 (Egyptian-VAR2) and GI-1 (H120) vaccines. Vaccines were administered at 1, 14 days of age, or both. The ciliostasis test, following wild-type VAR2 challenge at 28 days of age, indicated that classic H120+VAR2 at one day old followed by the VAR2 vaccine at 14 days of age provided the highest level of protection (89.58%). Similarly, administering VAR2 at 1 day of age and classic H120 at 14 days of age demonstrated substantial protection (85.42%). Conversely, administering only classic H120 and VAR2 at one day old resulted in the lowest protection level (54.17%). Tracheal virus shedding quantification and assessment of trachea and kidney degenerative changes were significantly lower in vaccinated groups compared to the unvaccinated-challenged group. In conclusion, a carefully planned vaccination regimen based on homologous vaccination offers the most effective clinical protection in broiler chickens.

Genomic characterization and pathogenicity of a novel fowl adenovirus serotype 11 isolated from chickens with inclusion body hepatitis in China

Fowl adenovirus serotype 11 (FAdV-11) is one of the primary causative agents of inclusion body hepatitis (IBH), which causes substantial economic losses in the world poultry industry. In this study, we characterized the genome of the fowl adenovirus serotype 11 (FAdV-11) isolate FJSW/2021. The full genome of FJSW/2021 was 44, 154 base pairs (bp) in length and had a similar organization to that of previously reported FAdV-11 isolates. Notably, compared with those of other reported FAdV-11 strains, the preterminal protein (pTP) of FAdV-11 FJSW/2021 has six amino acid (aa) insertions (S-L-R-I-I-C) between 470 and 475 and one aa mutation of L476F; moreover, the tandem repeat (TR) regions of TR1 and TR2 were 33 bp (1 repeat) and 1,080 bp (8 repeats) shorter than those of the Canadian nonpathogenic isolate ON NP2, respectively. The pathogenicity of FJSW/2021 was studied in 10-day-old specific pathogen-free chicken embryos following allantoic cavity inoculation and in 1-day-old, 1-wk-old and 2-wk-old SPF chickens following intramuscular inoculation with 107 TCID50 of the virus. The results showed that FJSW/2021 can induce typical severe IBH in chicks less than 2 wk old. These findings highlighted the genetic differences between the pathogenic and non-pathogenic FAdV-11 isolates. The data will provide guidance for identifying the virulence factors of FAdV-11 strains. The animal challenge model developed in our study will allow precise evaluation of the efficacy of potential FAdV-11 vaccine candidates.

Epidemiology, pathology, prevention, and control strategies of inclusion body hepatitis and hepatitis-hydropericardium syndrome in poultry: A comprehensive review

Infection with fowl adenoviruses (FAdVs) can result in a number of syndromes in the production of chicken, including inclusion body hepatitis (IBH), hepatitis-hydropericardium syndrome (HHS), and others, causing enormous economic losses around the globe. FAdVs are divided into 12 serotypes and five species (A-E; 1-8a and 8b-11). Most avian species are prone to infection due to the widespread distribution of FAdV strains. The genus aviadenovirus, which is a member of the adenoviridae family, is responsible for both IBH and HHS. The most popular types of transmission are mechanical, vertical, and horizontal. Hepatitis with basophilic intranuclear inclusion bodies distinguishes IBH, but the buildup of translucent or straw-colored fluid in the pericardial sac distinguishes HHS. IBH and HHS require a confirmatory diagnosis because their clinical symptoms and postmortem abnormalities are not unique to those conditions. Under a microscope, the presence of particular lesions and inclusion bodies may provide clues. Traditional virus isolation in avian tissue culture is more delicate than in avian embryonated eggs. Additionally, aviadenovirus may now be quickly and precisely detected using molecular diagnostic tools. Preventive techniques should rely on efficient biosecurity controls and immunize breeders prior to production in order to protect progeny. This current review gives a general overview of the current local and global scenario of IBH, and HHS brought on by FAdVs and covers both their issues and preventative vaccination methods.

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.

First Detection and Identification of FAdV-8b as the Causative Agent of an Outbreak of Inclusion Body Hepatitis in a Commercial Broiler Farm in Greece

Inclusion body hepatitis (IBH) is an economically important disease of chickens, with a worldwide distribution, caused by Fowl Aviadenoviruses (FAdVs). Currently, the increased number of cases, the virulence of the isolate strains, as well as the lack of cross-species protection highlight that detailed in-field data are fundamental for the development of successful control strategies. This case report provides a detailed clinicopathological investigation of an unusual IBH outbreak in a commercial broiler farm in the region of Macedonia, Greece. The farm consisted of 64,000 birds, originated from the same breeder stock and placed in three different houses (Flock A–C). At 20 days of age, a sudden increase in daily mortality was recorded in Flock A. It is worth mentioning that, although all flocks were serologically (indirect ELISA) and molecularly (RT-PCR) positive for FAdV, the mortality rate, attributed to IBH, was much higher in Flock A compared to others. The clinical manifestation included non-specific symptoms such as depression, inappetence, yellowish mucoid diarrhea, and lack of uniformity. At necropsy, typically, enlarged, pale, and friable livers were dominant, while sporadically lesions were recorded in the pancreas, kidneys, skeletal muscles, and lymphoid organs. The histopathological examination of liver samples showed multifocal inflammation, necrosis, and the presence of basophilic/ eosinophilic inclusion bodies in hepatocytes. In addition, the loss of the architecture of pancreatic lobules and the presence of fibrosis and foci of mononuclear cell aggregates were suggestive of chronic pancreatic inflammation. PCR analysis confirmed the presence of FAdV, belonging to species E, serotype FAdV-8b. Performance and financial calculations revealed that IBH increased Feed Conversion Ratio (FCR), feed cost/chick as well as feed cost/kg live weight, whereas the Livability (%) and the European Production Efficiency Factor (EPEF) were decreased in the most severely affected flocks (Flock A). This study is the first report of the detection and identification of FAdV serotypes associated with IBH in commercial broiler flocks in Greece. However, there is still a lack of information about the circulating FAdV serotypes in the country, and therefore epidemiological studies are needed to establish control strategies for IBH.

Molecular Detection of a Novel Fowl Adenovirus Serotype-4 (FadV-4) from an Outbreak of Hepatitis Hydropericardium Syndrome in Commercial Broiler Chickens in Egypt

Hepatitis hydropericardium syndrome (HHS) is an acute infectious disease caused by fowl adenovirus serotype-4 (FAdV-4), which mainly affects broilers aged 4-5 wk. During the winter of January 2021, a 32-day-old broiler flock (Cobb-500) suffered from unusually high mortality (15%) in the Alexandria Governorate, Egypt. The chickens showed depression, ruffled feathers, and greenish diarrhea besides the typical pathologic features of suspected HHS involving flabby hearts, accumulation of a straw-colored fluid in the pericardial sacs, and pale, enlarged hemorrhagic and friable livers with necrotic foci. The kidneys exhibited edema with uric acid depositions. Histopathologic examination of bird livers naturally infected with HHS showed multifocal areas of necrosis, vascular changes, and basophilic intranuclear inclusion bodies (INIB) in the hepatocytes. Molecular identification of the causative agent was accomplished by PCR and sequence analysis of the hyper-variable regions of loop 1 of the hexon gene of fowl aviadenovirus. A pathogenic strain of the novel genotype-4 (FAdV-4) was demonstrated, closely similar to the Israeli strain IS/1905/2019, with an identity of 98%. This is the first report to identify FADV-4 in Egypt, prompting further studies to elucidate its epidemiologic role in all poultry sectors and associated economic losses to provide insights to its control and prevention.

Emergence of fowl aviadenovirus C-4 in a backyard chicken flock in California

Fowl aviadenovirus (FAdV) species D and E are associated with inclusion body hepatitis (IBH); species C, serotype 4 (hereafter, FAdV4) is associated with hepatitis-hydropericardium syndrome (HHS) in young chickens. Outbreaks of HHS have led to significant losses in the poultry industry in several countries, predominantly in China. In April 2020, FAdV4 was detected in a remote backyard flock in California. In a mixed flock of chickens of various breeds and ages (6 mo to 2 y old), 7 of 30 were found dead within a week without premonitory signs. One additional bird died after the flock was relocated to fresh pasture, bringing the total mortality to 8 of 30 (27%). Postmortem examination of 3 birds revealed good body condition scores and active laying. One chicken had subtle hemorrhages throughout the liver, and the other 2 had diffusely dark mahogany livers. On histopathology, 2 chickens had hepatic necrosis with hepatocytes containing large, mostly basophilic, intranuclear inclusion bodies, identified by electron microscopy as 82.2-nm diameter adenoviral particles. Virus isolation and genomic sequencing performed on a liver sample revealed strains with 99.9% homology to FAdV4 isolates reported from China. To our knowledge, FAdV4 has not been reported in the United States to date. Furthermore, the chickens affected here were all adults and exhibited a variation of serotype 4 disease in which IBH was present but not hydropericardium.

First report of fowl aviadenovirus serotypes FAdV-8b and FAdV-11 associated with inclusion body hepatitis in commercial broiler and broiler-breeder flocks in Turkey

Inclusion body hepatitis (IBH), hydropericardium syndrome (HS), and gizzard erosion (GE) are all economically important diseases in the poultry industry worldwide and are all caused by fowl aviadenovirus (FAdV). It is important to identify the serotype of the virus to differentiate these diseases. In the present study, a total of six recent FAdV serotypes were isolated and identified in broiler and broiler-breeder flocks in Izmir, Manisa, and Aydın provinces of the Aegean region of Turkey between January and March 2019. The viruses were isolated from livers and pooled organs of chickens using primary chicken embryo kidney cell cultures (CEKC). Virus isolates were identified by PCR amplification of the loop 1 (L1) variable region of the hexon gene followed by Sanger sequencing. Sequence analysis revealed the presence of both FAdV-D (serotype 11) and FAdV-E (serotype 8b). The viruses that were isolated were associated with IBH, which is typically characterized by gross lesions such as enlarged and pale yellow liver with multiple petechial hemorrhages. Histopathological examination also showed necrotizing hepatitis with intranuclear inclusion bodies in hepatocytes. This study is the first report of the isolation and identification of FAdV serotypes associated with IBH in commercial broilers and broiler-breeder flocks in Turkey. The results of sequence analysis showed that FAdV-8b and FAdV-11 were the circulating serotypes that caused recent field outbreaks of IBH in the Aegean region between January and March, 2019.

Chronologic Analysis of Gross and Histologic Lesions Induced by Field Strains of FAdV-1, FAdV-8b, and FAdV-11 in Six-Week-Old Chickens

Inclusion body hepatitis (IBH) is a disease affecting broiler chicken flocks worldwide. Several serotypes of fowl adenovirus (FAdV) have been implicated in disease outbreaks, with and without immunosuppression as a predisposing factor. IBH usually occurs in flocks up to 30 days of age; it is seldom seen in older birds. The objective of this study was to determine whether the pathogenicity for older birds of three FAdV field strains, belonging to serotypes 1, 8b, and 11, in the absence of immunosuppressive factors, was akin to that for younger birds, and to establish an effective and economical disease model for assessing cross-protection between serotypes. To achieve this objective, the gross pathology, histopathology, and dissemination of virus were examined at multiple time points after inoculation of 6-wk-old, specific-pathogen-free chickens via intraperitoneal injection. Both FAdV-8b and FAdV-11 generated lesions typical of those associated with outbreaks of IBH, and they were shown to be primary pathogens. The presence and severity of hepatic lesions were used to define two disease stages: degeneration (1-5 days postinoculation) and convalescence (6-14 days postinoculation). During the degenerative stage, FAdV-8b was detected in the liver, kidney, and gizzard of most birds, whereas FAdV-11 was predominantly detected in the liver, and both viruses persisted in the gizzard into convalescence. The pathogenesis of two IBH-associated FAdV strains in 6-wk-old chickens confirms their high level of virulence and also provides an effective experimental model for investigation of cross-protection between FAdVs. It also demonstrates persistence of the virus in the gizzard long after infection, supporting the notion that it is a site of viral shedding.

First report of fowl adenovirus 8a from commercial broiler chickens in Egypt: molecular characterization and pathogenicity

This study was performed to isolate fowl adenovirus (FAdV) circulating in commercial meat-type chicken in Egypt during 2015 and to identify the pathogenicity of the isolated virus. Cloacal swabs were collected from 9 commercial broiler farms from chickens of 3-5 wk of age in Behira province in Egypt during 2015. FAdV was isolated on chicken embryo liver cells. The virus was identified by conventional polymerase chain reaction targeting a conserved region in the hexon gene. Moreover, phylogenetic analysis of the L1 loop of the hexon gene revealed that the isolated viruses clustered with reference strains belonging to FAdV serotype 8a. This is the first record of FAdV from Egypt on the GenBank. The isolated virus is closely related to strains directly associated with inclusion body hepatitis (IBH) causing considerable economic losses. Pathogenicity study of the virus did not show any mortality, although necropsy and histopathological examination displayed severe hepatitis and degenerative changes in the immune system after 5 d from infection, proving that the virus can cause IBH with intermittent shedding.

Hepato nephropathology associated with inclusion body hepatitis complicated with citrinin mycotoxicosis in a broiler farm

Aim:

Mortality in a broiler chicken farm was investigated for identifying the cause of mortality.

Materials and Methods:

A broiler farm with a population of 16000 succumbed to a disease outbreak. Clinical signs, vaccination history and mortality, were recorded. Necropsy examination and microscopic examination were carried out along with toxicological and molecular studies.

Results:

The clinical signs in the affected broiler birds were of non-specific nature with a total mortality of 26.39%. Postmortem examination and microscopical findings revealed hepatitis with basophilic intranuclear inclusion, splenitis, myocarditis, and nephritis. Glomerulonephritis was the prominent renal pathology recorded in this study. Polymerase chain reaction test confirmed the presence of fowl adenovirus (FAdV) genome in the target organs, and toxicological examination by thin-layer chromatography revealed the presence of a toxic level of citrinin in the feed samples.

Conclusion:

Based on various diagnostic investigations, the mortality in the flock was attributed to inclusion body hepatitis (IBH) complicated with citrinin mycotoxicosis. Thus, apart from liver pathology which occurs in a classical IBH cases, glomerulonephritis too occurs which are also a prominent finding which pathologists often miss. Thus, kidneys should also be examined histologically to assess the microscopic tissue alterations in poultry suspected for IBH along with a mycotoxicological analysis of feed. This will definitely throw light on the synergistic pathology elicited and exhibited by FAdV and mycotoxins in the poultry.

Fowl adenovirus-induced diseases and strategies for their control - a review on the current global situation

The stand-alone pathogenicity of fowl adenoviruses (FAdVs) had long been disputed, given the ubiquity of the viruses versus sporadic outbreaks, and variation between experimental studies. However, a globally emerging trend of FAdV-associated diseases has marked the past two decades, with hepatitis-hydropericardium syndrome mainly in Asia besides Arabian and Latin American countries, and geographically more disseminated outbreaks of inclusion body hepatitis. Finally, the appearance of FAdV-induced gizzard erosion (AGE) in Asia and Europe completed the range of diseases. Epidemiological studies confirmed serotype FAdV-4 as agent of hepatitis-hydropericardium syndrome, whereas inclusion body hepatitis is related to FAdV-2, -8a, -8b and -11. Members of the biologically more distant serotype FAdV-1 induce AGE. Urged by increasing problems in the field, numerous pathogenicity studies with FAdVs from outbreaks substantiated the primary aetiologic role of particular strains for distinct clinical conditions. Developments in the poultry industry towards highly specialized genetic breeds and rigorous biosecurity additionally contribute to the growing incidence of FAdV-related diseases. Confirming field observations, recent studies connected a higher susceptibility of broilers with their distinct physiology, implying the choice of bird type as a factor to be considered in infection studies. Furthermore, elevated biosecurity standards have generated immunologically naïve breeding stocks, putting broilers at risk in face of vertical FAdV transmission. Therefore, future prevention strategies should include adequate antibodies in breeders prior to production and - if necessary - vaccination, in order to protect progenies. This review aims to deliver a detailed overview on the current global situation about FAdV-induced diseases, their reproduction in vivo and vaccination strategies.

Commensal or pathogen - a challenge to fulfil Koch's Postulates

1. Infectious diseases have a large impact on poultry health and economics. Elucidating the pathogenesis of a certain disease is crucial to implement control strategies.

2. Multiplication of a pathogen and its characterisation in vitro are basic requirements to perform experimental studies. However, passaging of the pathogen in vitro can influence the pathogenicity, a process targeted for live vaccine development, but limits the reproduction of clinical signs.

3. Numerous factors can influence the outcome of experimental infections with some importance on the pathogen, application route and host as exemplarily outlined for Histomonas meleagridis, Gallibacterium anatis and fowl aviadenoviruses (FAdVs).

4. In future, more comprehensive and detailed settings are needed to obtain as much information as possible from animal experiments. Processing of samples with modern diagnostic tools provides the option to closely monitor the host–pathogen interaction.

The outcome of experimentally induced inclusion body hepatitis (IBH) by fowl aviadenoviruses (FAdVs) is crucially influenced by the genetic background of the host

In the present study, inclusion body hepatitis (IBH) was experimentally induced by oral inoculation of two groups of specific pathogen-free (SPF) broilers and two groups of SPF layers at day-old with either a fowl aviadenovirus (FAdV)-D or a FAdV-E strain. A substantial variation in the degree of susceptibility was observed with mortalities of 100 and 96% in the FAdV-E and D infected SPF broiler groups, respectively, whereas in the groups of infected SPF layers mortalities of only 20 and 8% were noticed. Significant changes in clinical chemistry analytes of all infected birds together with histopathological lesions indicated impairment of liver and pancreas integrity and functions. Furthermore, significantly lower blood glucose concentrations were recorded at peak of infection in both inoculated SPF broiler groups, in comparison to the control group, corresponding to a hypoglycaemic status. High viral loads were determined in liver and pancreas of SPF broilers already at 4 days post-infection (dpi), in comparison to SPF layers, indicating a somewhat faster viral replication in the target organs. Overall, highest values were noticed in the pancreas of SPF broilers independent of the virus used for infection. The actual study provides new insights into the pathogenesis of IBH, a disease evolving to a metabolic disorder, to which SPF broilers were highly susceptible. Hence, this is the first study to report a significant higher susceptibility of SPF broiler chickens to experimentally induced IBH in direct comparison to SPF layers.

Bioavailability and biochemical effects of diclofenac sodium 0.1% ophthalmic solution in the domestic chicken (Gallus gallus domesticus)

OBJECTIVE

To determine if topical ophthalmic diclofenac sodium 0.1% solution alters renal parameters in the domestic chicken, and to determine if the drug is detectable in plasma after topical ophthalmic administration.

ANIMALS

Thirty healthy domestic chickens.

PROCEDURES

Over 7 days, six birds were treated unilaterally with one drop of artificial tear solution (group 1), 12 birds were treated unilaterally (group 2) and 12 bilaterally (group 3) with diclofenac sodium 0.1% ophthalmic solution. Treatments were provided every 12 h in all groups. Pre- and post-treatment plasma samples from all birds were evaluated for changes in albumin, total protein, and uric acid. Post-treatment samples of all birds, collected 15 min post-administration, were analyzed by high-performance liquid chromatography with mass spectrometry for diclofenac sodium detection. A randomly selected renal sample from each group was submitted for histopathologic review.

RESULTS

Changes in pre- and post-treatment plasma albumin were significant (P < 0.05) in groups 2 and 3, but not for group 1. Pre- and post-treatment changes in total protein and uric acid were not significant for any group. Diclofenac sodium was not detectable (limit of detection = 0.10 ng/mL) in plasma samples from birds in group 1. Post-treatment concentration of diclofenac in group 3 was statistically greater than group 2 (P = 0.0008). Histopathologic changes did not identify diclofenac-induced acute renal tubular necrosis.

CONCLUSIONS

Ophthalmic diclofenac sodium 0.1% administered topically every 12 h in one or both eyes for 7 days is detectable in systemic circulation in the domestic chicken, but does not cause overt significant changes in plasma uric acid or total protein.