Investigation of a herpesvirus outbreak in mixed breeds of adult domestic ducks using next generation sequencing

Abstract

This report characterizes the first lethal outbreak of Marek’s disease on a large farm of mixed-breed adult ducks (>18,000) and identifies the pathogen that resulted in high mortality (35%). Clinical signs included inappetence, respiratory distress, depression, muscle weakness, and ataxia. Post mortem revealed enlarged fragile liver mottled with miliary whitish spots and an enlarged spleen. Histopathology revealed hepatocellular necrosis with eosinophilic intra-nuclear inclusion bodies, necrosis of splenic follicles and degeneration/necrosis of renal tubules. The disease was tentatively diagnosed as a herpesvirus infection, confirmed by virus isolation from the liver. DNA was isolated from 15-year-old archival formalin-fixed tissues from infected ducks and subjected to next generation sequencing (NGS). Despite highly degraded DNA, short stretches of G- and C-rich repeats (TTAGGG and TAACCC) were identified as telomeric repeats frequently found in herpesviruses. Megablast and further investigative bioinformatics identified presence of Marek’s disease virus (MDV), a Gallid alphaherpesvirus type 2 (GAHV-2), as the cause of the acute fatal infection. The source of infection may be attributed to a dead migratory flamingo found close to the duck enclosures three days prior to the outbreak; hence, GAHV-2 may also be responsible for the fatal infection of the flamingo accentuated by heat stress. Considering the possible spread of this highly contagious and lethal virus from a flamingo to the ducks, and the increasing zoonosis of animal viruses into humans, such as monkey B alphaherpesvirus transmission from macaques to humans with ~80% fatality, this observation has important ramifications for human health and safety of the poultry industry.

Multi-Barcode for Detection of Avian Bacterial and Viral Pathogens: A Review

“…However, none dealt with the detection of multiple disease agents in poultry. Instead, the papers dealt with individual agents, such as Newcastle disease (Cattoli et al 2011;Lebdah et al 2022;Akhtar et al 2023), Marek's (Maceachern et al 2011) (Damir et al 2023), and enteric viruses (Day and Zsak 2013).…”

The 28S rRNA RT-qPCR assay for host depletion evaluation to enhance avian virus detection in Illumina and Nanopore sequencing

“…In recent years, untargeted next-generation sequencing (NGS) technology has been increasingly employed for the detection and characterization of RNA viruses, particularly in the context of avian diseases ( Chen et al, 2013 ; Tang et al, 2015 ; Goraichuk et al, 2016 , 2017 , 2019 , 2021a , b ; Croville et al, 2018 ; Ferreri et al, 2019 ; Tal et al, 2019 ; Patzina-Mehling et al, 2020 ; Crossley et al, 2021 ; Chrzastek et al, 2022 ; Damir et al, 2023 ; Ip et al, 2023 ; Kariithi et al, 2023 ; Techera et al, 2023 ). Avian viruses, including highly pathogenic avian influenza virus (AIV) and Newcastle disease virus (NDV), pose significant threats to poultry populations and public health ( Alexander, 1998 ; Suarez, 2017 ; Swayne et al, 2020 ).…”