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Updated: Aug 25, 2026
In Ovo Intravascular Injection in Chicken Embryos
Published on: June 3, 2022
Detection and localization of avian alphaherpesviruses in embryonic tissues following in ovo exposure
Catherine A St Hill1, Robert F Silva, Jagdev M Sharma
1Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Minnesota, 258 Veterinary Science Building, 1971 Commonwealth Avenue, St. Paul, MN 55108, USA.
Abstract:
We investigated whether chicken embryonic tissues are susceptible to infection with virulent Marek's disease virus (MDV). Groups of embryonic day (ED) 17 chicken embryos and 1-day-old chicks were compared for tissue sites of viral persistence of MDV and herpesvirus of turkeys (HVT) in lungs, thymuses, bursae of Fabricius and spleens. MDV DNA was detectable in the lungs and thymuses of embryos at 3 days post-inoculation (DPI) by in situ hybridization, while HVT DNA was only present in embryonic lungs. The target cells in lungs and thymuses appeared non-lymphoid and lymphoid, respectively. By 5 days post-inoculation, both viruses were detectable in all organs examined and persisted after hatch. Although MDV DNA was present in the embryo, there was little evidence of viral replication. These findings demonstrate the differences in pathogenesis of embryonic infection with MDV and HVT and provide evidence that the chicken embryo is susceptible to infection with a virulent avian herpesvirus.
Insights
Chicken embryos are susceptible to virulent Marek's disease virus (MDV) and herpesvirus of turkeys (HVT) infection, with viral DNA detected in embryonic tissues. However, significant viral replication was not observed in embryos, indicating distinct pathogenesis.
Area of Science:
- Avian Virology
- Infectious Disease Pathogenesis
- Poultry Health
Background:
- Marek's disease virus (MDV) is a significant pathogen in poultry, causing substantial economic losses.
- Understanding the early stages of viral infection, including embryonic susceptibility, is crucial for developing effective control strategies.
- Herpesvirus of turkeys (HVT) serves as a vaccine strain for MDV, and comparative studies of their embryonic pathogenesis are informative.
Purpose of the Study:
- To determine if chicken embryonic tissues are susceptible to infection by virulent Marek's disease virus (MDV).
- To compare the tissue tropism and persistence of MDV and HVT in chicken embryos and newly hatched chicks.
- To investigate the cellular targets and replication potential of these viruses during embryonic development.
Main Methods:
- Infection of embryonic day 17 (ED17) chicken embryos and 1-day-old chicks with MDV and HVT.
- Detection of viral DNA in various organs (lungs, thymuses, bursae of Fabricius, spleens) using in situ hybridization at 3 and 5 days post-inoculation (DPI).
- Comparison of viral persistence and distribution between embryonic and post-hatch stages.
Main Results:
- MDV DNA was detected in embryonic lungs and thymuses by 3 DPI, while HVT DNA was primarily found in embryonic lungs.
- Target cells for MDV in lungs were non-lymphoid, and in thymuses were lymphoid; HVT targeted non-lymphoid lung cells.
- By 5 DPI, both viruses were present in all examined organs and persisted post-hatch, though MDV showed limited replication in embryos.
Conclusions:
- Chicken embryos are susceptible to infection with virulent avian herpesviruses like MDV and HVT.
- There are distinct differences in the early pathogenesis and tissue tropism of MDV and HVT during embryonic infection.
- Embryonic infection with MDV occurs, but with minimal evidence of viral replication, suggesting a different pathway compared to post-hatch infection.
