Duck hepatitis a virus: Full-length genome-based phylogenetic and phylogeographic view during 1986-2020

Single-cell RNA sequencing reveals intrahepatic signature related to pathobiology of duck hepatitis A virus type 3 (DHAV-3) infection

DHAV-3 is one of the main causative agents of duck viral hepatitis (DVH), an acute and highly lethal infectious disease in duck industry. However, the understanding of the pathogenesis of this virus in ducklings is limited. To dissect the molecular characteristics associated with pathobiology of ducklings to DHAV-3, we applied single-cell RNA-sequencing approach to profile the transcriptome of 1.4 million cells from 14 livers of DHAV-3 susceptible (S) and resistant (R) ducklings during viral infection and 4 uninfected healthy controls. We found that infected S ducks exhibited the activation of type I and II interferon pathways with elevated expression of interferon-stimulated genes (ISGs) compared to infected R ducks and healthy controls. DHAV-3 promoted proinflammatory phenotype and inhibited the cell apoptosis pathway of Kupffer cells of S ducks. Furthermore, we observed the elevated expression of host factor PLAC8 in S ducks and validated its ability to facilitate the infection of DHAV-3. We identified significant dysregulation of various genes in complement and coagulation cascades in hepatocytes2 exclusive to S ducks, together with over-secretion of ANGPTL4 from endothelial cells in S ducks which is confirmed to promote cellular migration, suggesting etiology of coagulopathic complications in ducks with severe DVH. Collectively, this study provides a rich resource for understanding the inflammatory immune signatures and cell communications underlying the pathogenesis of DHAV-3 infection, which may accelerate the development of better diagnostic methods and strategies for controlling this disease.

Advances in the Duck Hepatitis A virus and lessons learned from those in recent years

Duckviral hepatitis (DVH) is a highly lethal and highly transmissible viral infectious disease of ducklings caused by the Duck Hepatitis A virus (DHAV), which is characterized by clinical neurological symptoms and liver enlargement with spot-like hemorrhages. In recent years, the change in diagnosis, prevention, and control of the disease has brought great challenges due to the mutation and recombination of epidemic strains, outbreaks and epidemics of genotype 3 (DHAV-3), and the rising trend of mixed infections. Here, we review DHAV on aspects of molecular biological characteristics, epidemiology, pathologic changes, pathogenesis, diagnosis, prevention, and control of the DVH to provide a scientific basis for basic and applied research in the future.

One-Step Multiplex Real-Time Fluorescent Quantitative Reverse Transcription PCR for Simultaneous Detection of Four Waterfowl Viruses

Duck Tembusu virus (DTMUV), duck hepatitis virus (DHV), Muscovy duck reovirus (MDRV), and Muscovy duck parvovirus (MDPV) represent four emergent infectious diseases impacting waterfowl, which can be challenging to differentiate due to overlapping clinical signs. In response to this, we have developed a one-step multiplex real-time fluorescence quantitative reverse transcription PCR (qRT-PCR) assay, capable of simultaneously detecting DTMUV, DHV, MDRV, and MDPV. This method exhibits high specificity, avoiding cross-reactivity with other viruses such as Fowl adenoviruses (FADV), infectious bursal disease virus (IBDV), infectious bronchitis virus (IBV), infectious laryngotracheitis virus (ILTV), Haemophilus paragallinarum (Hpg), duck circovirus (DUCV), goose astrovirus (GoAstV), and mycoplasma gallisepticum (MG). The limit of detection (LOD) established for DTMUV, DHV, MDRV, and MDPV was determined to be 27 copies/μL. In the repeatability test, the intra-assay and inter-assay coefficients of variation (CVs) of the recombinant plasmid standard were less than 2%. Utilizing this method, we analyzed 326 clinical specimens sourced from Guangxi over the period spanning October 2021 through December 2023, yielding promising and precise outcomes. The qRT-PCR method established herein exhibits commendable specificity, sensitivity, and repeatability. Furthermore, it boasts a high clinical detection rate, making it a highly effective tool for diagnosing these pathogenic agents in waterfowl.

Duck hepatitis A virus 1-encoded 2B protein disturbs ion and organelle homeostasis to promote NF-κB/NLRP3-mediated inflammatory response

Previous studies by our group and others have highlighted the critical role of hyperinflammation in the pathogenicity of duck hepatitis A virus 1 (DHAV-1), an avian picornavirus that has caused significant devastation in the duck industry worldwide for decades. However, the precise mechanisms by which DHAV-1 infection regulates the inflammatory responses, particularly the production of IL-1β, remain poorly understood. In this study, we demonstrate that DHAV-1 infection triggers NF-κB- and NLRP3 inflammasome-mediated IL-1β production. Mechanistically, DHAV-1 infection, particularly its replication and translation, disrupts cellular homeostasis of Ca2+, K+, ROS and cathepsin, which act cooperatively as assembly signals for NLRP3 inflammasome activation. By screening DHAV-1-encoded proteins, we identified that the viroporin 2B dominates NF-κB as well as NLRP3 inflammasome activation. Mutation analysis revealed that I43 within the 2B protein is the key amino acid for Ca2+ mobilization and subsequent activation of NF-κB transcriptional activity and NLRP3 inflammasome. Moreover, DHAV-1 infection and the 2B protein activate the MAVS- and MyD88-NF-κB pathways by relay, providing the necessary priming signals for NLRP3 inflammasome activation. In summary, our findings elucidate a mechanism through which DHAV-1 triggers inflammatory responses via NF-κB/NLRP3 inflammasome activation, offering new perspectives on DHAV-1 pathogenesis and informing the development of targeted anti-DHAV-1 treatments.

Establishment and Application of Mismatch Amplification Mutation Assay-PCR for Rapid Detection and Differentiation of Duck Hepatitis A Virus-1 Attenuated Vaccine and Wild Strains

Duck hepatitis A virus type 1 (DHAV-1) is the main pathogen causing viral hepatitis in ducks, marked by high contagion and acute mortality. Live attenuated DHAV-1 vaccines are widely used to control the disease. This study aims to develop a mismatch amplification mutation assay (MAMA)-PCR for the rapid detection and differentiation of Korean DHAV-1 wild-type strains from vaccine strains. A MAMA primer was designed to target a single nucleotide polymorphism (SNPs) at position 2276 within the VP1 gene, allowing differentiation in a single PCR reaction. The MAMA-PCR accurately identified both strains, with detection limits of 100.5 ELD50/mL and 102.3 ELD50/mL, respectively. The MAMA-PCR demonstrated specificity, showing no cross-reactivity with 12 other viral and bacterial pathogens. The MAMA-PCR was applied to 89 farms, yielding results consistent with nested-PCR and sequence determination, identifying four positive farms for DHAV-1 vaccine strains. In conclusion, this study is the first to employ the MAMA-PCR method to distinguish between DHAV-1 wild-type and vaccine strains. The developed method is rapid, simple, specific, and sensitive, thereby serving as an effective tool for clinical diagnostics in identifying and differentiating between Korean DHAV-1 wild-type and vaccine strains.

Molecular Detection and Genetic Characterization of Vertically Transmitted Viruses in Ducks

To investigate the distribution and genetic variation in four vertically transmitted duck pathogens, including duck hepatitis B virus (DHBV), duck circovirus (DuCV), duck hepatitis A virus 3 (DHAV-3), and avian reoviruses (ARV), we conducted an epidemiology study using PCR and RT-PCR assays on a duck population. We found that DHBV was the most prevalent virus (69.74%), followed by DuCV (39.48%), and then ARV (19.92%) and DHAV-3 (8.49%). Among the 271 duck samples, two, three or four viruses were detected in the same samples, indicating that the coinfection of vertical transmission agents is common in ducks. The genetic analysis results showed that all four identified DuCV strains belonged to genotype 1, the DHAV-3 strain was closely clustered with previously identified strains from China, and the ARV stain was clustered under genotype 1. These indicate that different viral strains are circulating among the ducks. Our findings will improve the knowledge of the evolution of DuCV, DHAV-3, and ARV, and help choose suitable strains for vaccination.