Identification of four serotypes of fowl adenovirus in clinically affected commercial poultry co-infected with chicken infectious anaemia virus in Trinidad and Tobago

A multiplex fluorescence-based loop-mediated isothermal amplification assay for identifying chicken parvovirus, chicken infectious anaemia virus, and fowl aviadenovirus serotype 4

Chicken parvovirus (ChPV), chicken infectious anaemia virus (CIAV) and fowl adenovirus serotype 4 (FAdV-4) are avian viruses that have emerged in recent years and have endangered the global poultry industry, causing great economic loss. In this study, a multiplex fluorescence-based loop-mediated isothermal amplification (mLAMP) assay for detecting ChPV, CIAV and FAdV-4 was developed to simultaneously diagnose single and mixed infections in chickens. Three primer sets and composite probes were designed according to the conserved regions of the NS gene of ChPV, VP1 gene of CIAV and hexon gene of FAdV-4. Each composite probe was labelled with a different fluorophore, which was detached to release the fluorescence signal after amplification. The target viruses were distinguished based on the colour of the mLAMP products. The mLAMP assay was shown to be sensitive, with detection limits of 307 copies of recombinant plasmids containing the ChPV target genes, 749 copies of CIAV and 648 copies of FAdV-4. The assay exhibited good specificity and no cross-reactivity with other symptomatically related avian viruses. When used on field materials, the results of the mLAMP assay were in 100% agreement with those of the previously published PCR assay. The mLAMP assay is rapid, economical, sensitive and specific, and the results of amplification are directly observable by eye. Therefore, the mLAMP assay is a useful tool for the clinical detection of ChPV, CIAV and FAdV-4 and can be applied in rural areas.

Molecular epidemiology analysis of fowl adenovirus detected from apparently healthy birds in eastern China

BACKGROUND

Fowl adenovirus is of major concern to the poultry industry worldwidely. In order to monitor the prevalent status of Fowl adenovirus in China, a total of 1920 clinical samples from apparently healthy birds in the 25 sites of poultry flocks, Slaughterhouse and living bird markets from 8 provinces in eastern China were collected and detected by PCR, sequencing, and phylogenetic analysis.

RESULTS

The epidemiological survey showed that Fowl adenoviruses were detected in living bird markets, and circulating in a variety of fowl species, including chickens, ducks, goose and pigeons. Among the 1920 clinical samples, 166 samples (8.65%) were positive in the fowl adenovirus PCR detection. In this study, totally all the 12 serotypes (serotypes of 1, 2, 3, 4, 5, 6, 7, 8A, 8B, 9, 10 and 11) fowl adenoviruses were detected, the most prevalent serotype was serotype 1. Phylogenetic analysis indicated that 166 FAdVs of 12 serotypes were divided into 5 fowl adenovirus species (Fowl aviadenovirus A, B, C, D, E).

CONCLUSIONS

In the epidemiological survey, 8.65% of the clinical samples from apparently healthy birds were positive in the fowl adenovirus PCR detection. Totally all the 12 serotypes fowl adenoviruses were detected in a variety of fowl species, which provided abundant resources for the research of fowl adenoviruses in China. The newly prevalent FAdV serotypes provides valuable information for the development of an effective control strategy for FAdV infections in fowls.

A new rapid and sensitive method for detecting chicken infectious anemia virus

Since the chicken infectious anemia virus (CIAV) was discovered in 1979, which has been reported as an economically significant and immunosuppressive poultry disease in the world. A novel clinical detection method for the prevention and control of CIAV in the poultry sector is urgently needed. Here, we established a real-time recombinase-aided amplification assay (RAA) for CIAV on-site with a rapid, highly sensitive, strongly specific, low-cost, and simple operational molecular diagnosis detection method. The primers and probe were developed using the CIAV VP2 gene sequence, which has a 117-bp specific band. This assay, which could be carried out at 41°C and completed in 30 min without cross-reactivity with other viruses, had the lowest detection limit of 10 copies of CIAV DNA molecules per reaction. Furthermore, the kappa value of this assay was 0.947, the sensitivity was 93.33%, and the specificity was 100% when compared to the real-time quantitative polymerase chain reaction assay (real-time qPCR). These results indicate that using a real-time RAA assay to detect CIAV on-site could be beneficial. In the future, the real-time RAA test may be a regular assay for the prevention and control of CIAV, as well as help the reduction of economic losses in the poultry business.

A comprehensive review of viruses in terrestrial animals from the Caribbean islands of Greater and Lesser Antilles

Viruses pose a major threat to animal health worldwide, causing significant mortalities and morbidities in livestock, companion animals and wildlife, with adverse implications on human health, livelihoods, food safety and security, regional/national economies, and biodiversity. The Greater and Lesser Antilles consist of a cluster of islands between the North and South Americas and is habitat to a wide variety of animal species. This review is the first to put together decades of information on different viruses circulating in companion animals, livestock, and wildlife from the Caribbean islands of Greater and Lesser Antilles. Although animal viral diseases have been documented in the Caribbean region since the 1940s, we found that studies on different animal viruses are limited, inconsistent, and scattered. Furthermore, a significant number of the reports were based on serological assays, yielding preliminary data. The available information was assessed to identify knowledge gaps and limitations, and accordingly, recommendations were made, with the overall goal to improve animal health and production, and combat zoonoses in the region. This article is protected by copyright. All rights reserved.

Gizzard erosions in broiler chickens in Sweden caused by fowl adenovirus serotype 1 (FAdV-1): investigation of outbreaks, including whole-genome sequencing of an isolate

AbstractThe present paper describes the investigation of the first outbreaks of adenoviral gizzard erosions (AGE) in Sweden, in five broiler flocks. The investigation includes whole viral genome sequencing and investigation of genomic organisation and sequence relationships with other adenoviruses. All five flocks had a history of decreased growth and uneven size of birds since nine to ten days of age. Macroscopically, lesions consistent with AGE (detached koilin layers, discoloration, bleeding, erosions) were identified in gizzards in all five flocks. In four flocks histology was performed, and degeneration and inflammation of the koilin layer and gizzard mucosa were identified in all four. In one flock, intranuclear inclusion bodies typical for fowl adenovirus (FAdV) were detected in trapped epithelial cells in the koilin layer. In four flocks in situ hybridization was performed, and cells positive for FAdV serotype 1 (FAdV-1) were demonstrated in the koilin layer and gizzard mucosa. FAdV species A (FAdV-A) was detected in gizzard, liver, caecal tonsils and bursa of Fabricii by polymerase chain reaction (PCR) and sequencing. Ten out of ten examined parent flocks of the affected chickens were seropositive for FAdV, indicating former or on-going infection. However, FAdV was not detected in embryos from seropositive parent flocks and thus vertical transmission was not demonstrated. The entire nucleotide sequence of one sample was determined and found to be 43,856 base pairs (bp) in length. The genome sequence and organisation were found to be similar to that of the reference apathogenic avian adenovirus "chicken embryo lethal orphan" (CELO).

Characterization of Co-infection With Fowl Adenovirus Serotype 4 and 8a

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-4) and strain AH720 from species E serotype 8a (FAdV-8a) were used to assess the pathogenicity of their co-infection in specific-pathogen-free (SPF) chickens. Compared with chickens infected with FAdV-4 alone, those co-infected with FAdV-4 and FAdV-8a showed similar clinical symptoms, mortality rates and degree of tissue lesions, and notably decreased viral loads of HN. Conversely, the viral loads of AH720 increased markedly in the co-infection group compared with that in chickens infected with AH720 strain alone. Increased viral loads of AH720 in the liver were suspected to contribute to the pathogenicity of chickens co-infected with the HN and AH720 strains. This was further investigated by histopathology and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining analyses. Collectively, these data indicated that co-infection with FAdV-4 and FAdV-8a suppresses the replication and proliferation of FAdV-4 but enhances the replication and proliferation of FAdV-8a in chicken liver. This study will provide valuable information for the further investigation of the interactions between FAdV-4 and FAdV-8a during co-infection.

A recent perspective on fiber and hexon genes proteins analyses of fowl adenovirus toward virus infectivity-A review

Fowl adenovirus (FAdV) is a double-stranded DNA virus with a non-enveloped structure comprising three major proteins known as hexon, penton, and fiber. Molecular analysis which emphasizes on hexon and fiber proteins is currently the major focus of curiosity for FAdV antigenicity and pathogenicity. Recently, disease outbreaks associated with FAdV infections such as inclusion body hepatitis, hepatitis hydropericardium syndrome, and gizzard erosion, were commonly reported and continue to increase worldwide. Studies on the virulence gene of the virus were intensively conducted to provide a better understanding on the role of these major capsid proteins in the development of a safe and effective vaccine against the disease in the poultry industry. This paper highlights the variations of the fiber and hexon genes, their importance in genotypes and serotypes differentiation, and infectivity between FAdV strains. It appears that the L1 loop of hexon and the knob of fiber genes are the infectivity markers for FAdV infection. The fiber-2 protein plays a major role in FAdV pathogenicity than the hexon protein, while the fiber-1 protein is important for viral replication and assembly, regardless of virulence capability instead of infectivity. The hexon protein plays a major role in virus infectivity and tissue tropism. These findings could further enhance the knowledge of FAdV strains’ classification and evolution, diagnosis, and strategies to prevent and control FAdV infection and outbreaks in chicken farms.

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

Inclusion body hepatitis (IBH) is, in some cases, a fatal disease affecting fowl by adenovirus strains which are subdivided into 5 species (A-E). In the current study, we investigated sequences from the Loop L1 region of the hexon gene of sequences of adenovirus field stains 1/A and 11/D isolated from a poultry flock co-infected with IBH and avian reoviruses ARVs. In early 2021, an epidemiologic survey highlighted the coinfection adenoviruses with other viruses (orthoreovirus infection) as being particularly deleterious within the poultry industry. Here, we investigated the Loop L1 HVR1-4 region of the hexon gene with relative synonymous codon usage (RSCU) designation and RSCU inclusive of all the mutations. These are the first results that have been presented on fowl adenovirus species A and D with simultaneous reovirus infection in 38-days old broiler chickens in Poland.

Experimental co-infection of variant infectious bursal disease virus and fowl adenovirus serotype 4 increases mortality and reduces immune response in chickens

Infectious bursal disease virus (IBDV) and fowl adenovirus serotype 4 (FAdV-4) cause infectious bursal disease (IBD) and hydropericardium-hepatitis syndrome, respectively. Recently, studies have reported co-infections of poultry with IBDV and FAdV-4, which is an important problem in the poultry industry. Here, the variant IBDV strain ZD-2018-1 and FAdV-4 isolate HB1501 were used to assess the pathogenicity of co-infection in 1-day-old specific pathogen-free (SPF) chickens. Compared with chickens infected with only FAdV-4, those coinfected with IBDV and FAdV-4 showed enhanced clinical symptoms, higher mortality, more severe tissue lesions, and higher biochemical index levels. Furthermore, the expression of interleukin (IL)-6, IL-1β, and interferon-γ mRNAs in the IBDV-FAdV-4 coinfected chickens was delayed, and the antibody response levels were significantly lower in those birds compared with the FAdV-4-infected chickens. These results indicate that co-infection with variant IBDV ZD-2018-1 and FAdV-4 HB1501 could significantly promote the pathogenicity of FAdV-4 and reduce the immune response in chickens. This study provides the foundation for further investigation of the interaction mechanism in IBDV and FAdV-4 co-infection.

A tandem mass tag-based quantitative proteomic analysis of fowl adenovirus serotype 4-infected LMH cells

Fowl adenovirus serotype 4 (FAdV-4) is recognized as an economically important pathogen for the poultry industry worldwide. FAdV-4 infection causes a metabolic disturbance of hepatocytes, leading to hydropericardium-hepatitis syndrome (HHS) in poultry. However, the metabolic response of hepatocytes to FAdV-4 infection remains poorly investigated. Here, a tandem mass tag (TMT)-based approach was first used to quantitatively identify differentially expressed proteins (DEPs) in leghorn male hepatoma (LMH) cells infected with the virulent FAdV-4 strain GY. We identified 666 DEPs associated with many biological processes and pathways, according to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses. Functional enrichment analysis revealed that three pathways, including metabolism-related signaling pathways, apoptosis, and autophagy responses, were enriched during FAdV-4 infection. Moreover, excessive induction of metabolism-related signaling pathways by FAdV-4 infection might be associated with HHS induced by the virus. Meanwhile, among the proteins in these pathways, RRM2, SAE1, AEN, and RAD50 were verified through western blotting to be markedly altered in FAdV-4-infected LMH cells. Notably, overexpression of SAE1 inhibited the replication of FAdV-4 in vitro, whereas silencing of SAE1 expression promoted the replication of the virus. Collectively, our findings show for the first time that SAE1 is a host cellular protein that plays roles in regulating the life cycle of FAdV-4.

Propagation and Molecular Characterization of Fowl Adenovirus Serotype 8b Isolates in Chicken Embryo Liver Cells Adapted on Cytodex™ 1 Microcarrier Using Stirred Tank Bioreactor

Large volume production of vaccine virus is essential for prevention and control of viral diseases. The objectives of this study were to propagate Fowl adenovirus (FAdV) isolate (UPM08136) in chicken embryo liver (CEL) cells adapted to Cytodex™ 1 microcarriers using stirred tank bioreactor (STB) and molecularly characterize the virus. CEL cells were prepared and seeded onto prepared Cytodex™ 1 microcarriers and incubated first in stationary phase for 3 h and in STB at 37 °C, 5% CO2, and 20 rpm for 24 h. The CEL cells were infected with FAdV isolate (UPM08136) passage 5 (UPM08136CELP5) or passage 20 (UPM08136CELP20) and monitored until cell detachment. Immunofluorescence, TCID50, sequencing, alignment of hexon and fiber genes, and phylogenetic analysis were carried out. CEL cells were adapted well to Cytodex™ 1 microcarriers and successfully propagated the FAdV isolates in STB with virus titer of 107.5 (UPM08136CELP5B1) and 106.5 (UPM08136CELP20B1) TCID50/mL. These isolates clustered with the reference FAdV serotype 8b in the same evolutionary clade. The molecular characteristics remained unchanged, except for a point substitution at position 4 of the hexon gene of UPM08136CELP20B1, suggesting that propagation of the FAdV isolate in STB is stable and suitable for large volume production and could be a breakthrough in the scale-up process.