Dataset Information

Airborne Transmission of a Serotype 4 Fowl Adenovirus in Chickens.

ABSTRACT: Serotype 4 fowl adenovirus (FAdV-4) is the main pathogen for hydropericardium syndrome (HPS) in chickens. It has caused major economic losses in the global poultry industry. Currently, FAdV-4's transmission routes in chickens remain unclear. Here we investigate the airborne transmission routes of FAdV-4 in chickens. A total of 45 ten-day-old chickens were equally divided into three groups (infected group/isolator A, airborne group/isolator B, and control group/isolator C). Of note, isolators A and B were connected by a leak-free pipe. The results showed that the virus could form a viral aerosol, detected in isolators two days post infection (dpi). The viral aerosol reached a peak at 4 dpi in the infected group. Healthy chickens in the airborne group were infected by the virus at 8 dpi. The chickens of the airborne group demonstrated subclinical symptoms capable of shedding the virus for some time. This finding suggests that FAdV-4 can be efficiently transmitted among chickens by aerosol transmission. These findings have significant implications for developing strategies to control this infectious disease epidemic.

SUBMITTER: Li G

PROVIDER: S-EPMC6466269 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Airborne Transmission of a Serotype 4 Fowl Adenovirus in Chickens.

Li Gang G Yu Guanliu G Niu Yujuan Y Cai Yumei Y Liu Sidang S

Viruses 20190314 3

Serotype 4 fowl adenovirus (FAdV-4) is the main pathogen for hydropericardium syndrome (HPS) in chickens. It has caused major economic losses in the global poultry industry. Currently, FAdV-4's transmission routes in chickens remain unclear. Here we investigate the airborne transmission routes of FAdV-4 in chickens. A total of 45 ten-day-old chickens were equally divided into three groups (infected group/isolator A, airborne group/isolator B, and control group/isolator C). Of note, isolators A a ...[more]

PMID: 30875756

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Project description:Hydropericardium syndrome and inclusion body hepatitis, together called hydropericardium-hepatitis syndrome, are acute infectious diseases found in chickens. These diseases are caused primarily by fowl adenovirus serotype 4 (FAdV-4) strains. In this study, we isolated a FAdV-4 strain (SD0828) from clinically diseased chickens and phylogenetically analyzed the L1 loops of the hexon protein sequences in 3-week-old specific pathogen-free chickens and ducks infected intramuscularly and orally, determining differences in the pathogenicity by observing clinical signs and gross and histological lesions. We also detected the viral load in tissue samples. Postinfection necropsy showed that all chickens but no ducks exhibited typical necropsy lesions. Additionally, all chickens infected intramuscularly died within 2 days postinfection (dpi), and all those infected orally died within 5 dpi, whereas no infected ducks died before 28 dpi. Quantitative real-time polymerase chain reaction analysis was used to determine the viral load in the tissues of hearts, livers, spleens, lungs, and kidneys and in cloacal cotton swabs from infected chickens and ducks at 1, 2, 3, 5, 7, 14, 21, and 28 dpi. The greatest number of viral DNA copies was found in the livers of infected chickens, yet no virus was found in any samples from infected ducks. In addition, the viral load increased over time in both chicken and duck embryo fibroblasts (CEFs and DEFs, respectively); in the former, replication speed was significantly greater than in the latter. Innate immune responses were also studied, both in vivo and in vitro. In CEFs, DEFs, and chickens infected intramuscularly, but not in infected ducks, mRNA expression levels of proinflammatory cytokines (interleukin-6 and -8) and interferon-stimulated genes (Mx and OAS) were significantly upregulated. Although some cytokines showed significant upregulation in the oral chickens, most did not change significantly. Finally, the duck retinoic acid-inducible gene I and its caspase activation and recruitment domain both had significant antiviral functions in CEFs, particularly after 24 h postinfection. Taken together, this research provides new insights into the interactions between FAdV-4 and the innate immune systems of studied hosts (chickens and ducks).

Project description:FAdV-4 is the major strain of adenovirus that responsible for hydro-pericardial syndrome (HPS) in poultry. In this study, the virus's specific gene fragments were isolated from clinically suspected cases and amplified by PCR. Finally, after a viral infection to investigate the immune response of the host, the gene expression of MHC (major histo-compatible) molecules (MHCIα, MHCIIβ), Ii (Invariant Chain) gene, inflammatory cytokines (IFN-β, IFN-γ, and IL-1β), and transcription factors (MDA5, STING, IRF7, and NF-kB) were detected by real-time PCR (fluorescence technology). The results of sequence comparison showed that the clinically isolated virus was 100% homologous to a virulent strain of avian adenovirus group C serotype 4 (FAdV-4), which were named AH-FAdV-4. The TCID50 and pathogenicity of the virus were determined that was 106.52/0.1 mL with a mortality rate of 100% in chickens and 0% in ducks. Furthermore, results showed that the expression level of MHCIα, MHCIIβ, and Ii genes in chicken embryo kidney cells significantly (P < 0.01) upregulated (increased) after infection, which was 43, 5.2, and 2.5 times higher than the control group. With the addition of PDTC, an inhibitor of NF-kB, then the expression level of MHCIα, MHCIIβ, and Ii was decreased significantly (P < 0.01) than the control group. The transcription levels of these genes were decreased 0.64, 0.27, and 0.26 respectively. Simultaneously, the expression levels of IFN-β, IFN-γ, and IL-1β were also significantly (P < 0.01) up-regulated (increased) 7.8, 22.7, and 5 times higher than the control group. It was found that up-regulation of STING and NF-κB pathways are directly involved in the regulation of inflammatory cytokines (IFN-β, IFN-γ, and IL-1β), MHC molecules (MHCIα, MHCIIβ), and Ii gene. The results also showed that the gene regulation pathways consecutively increased the expression levels of MDA5, STING, IRF7, and NF-kB. It is conducted that the expression levels of cytokines, MHC molecules, and li gene were increased by STING and NF-kB pathways.

Dataset Information

Airborne Transmission of a Serotype 4 Fowl Adenovirus in Chickens.

Publications

Airborne Transmission of a Serotype 4 Fowl Adenovirus in Chickens.

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