In vivo imaging reveals novel replication sites of a highly oncogenic avian herpesvirus in chickens

PLoS Pathog. 2022 Aug 29;18(8):e1010745. doi: 10.1371/journal.ppat.1010745. eCollection 2022 Aug.

Abstract

In vivo bioluminescence imaging facilitates the non-invasive visualization of biological processes in living animals. This system has been used to track virus infections mostly in mice and ferrets; however, until now this approach has not been applied to pathogens in avian species. To visualize the infection of an important avian pathogen, we generated Marek's disease virus (MDV) recombinants expressing firefly luciferase during lytic replication. Upon characterization of the recombinant viruses in vitro, chickens were infected and the infection visualized in live animals over the course of 14 days. The luminescence signal was consistent with the known spatiotemporal kinetics of infection and the life cycle of MDV, and correlated well with the viral load measured by qPCR. Intriguingly, this in vivo bioimaging approach revealed two novel sites of MDV replication, the beak and the skin of the feet covered in scales. Feet skin infection was confirmed using a complementary fluorescence bioimaging approach with MDV recombinants expressing mRFP or GFP. Infection was detected in the intermediate epidermal layers of the feet skin that was also shown to produce infectious virus, regardless of the animals' age at and the route of infection. Taken together, this study highlights the value of in vivo whole body bioimaging in avian species by identifying previously overlooked sites of replication and shedding of MDV in the chicken host.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chickens
  • Ferrets
  • Herpesviridae*
  • Herpesvirus 2, Gallid*
  • Marek Disease*
  • Mice

Grants and funding

This work was supported by a Transnational Access (TNA) grant from the VetBioNet INFRAIA program (EU H2020 N°731014 to BK) and a Lichtenberg grant from the Volkswagen Foundation (A112662 to BK). CM was supported by a French MESRI PhD fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.