Characterization of Viraemic Cells in a Murine Model of EHV‐1 Infection

Abstract

Equine herpes virus (EHV‐1) causes respiratory infection in equine, abortion, paresis, neonatal death, and retinopathy and the virus may become latent following initial infection. Virus entry is via respiratory route, and the virus replicates in ciliated and non‐ciliated epithelial cells of the respiratory tract and in Type 1 and Type 2 pneumocytes in the lung parenchyma. After viral replication in the respiratory system, the virus is disseminated to other parts of body via viraemic cells. The virus crosses the placenta which leads to abortion of live or dead fetuses without premonitory signs. Infected horses show transient immunity after natural or experimental infection and immune responses to EHV‐1, but the immunoprotective status begins to decline after few months of infection. Due to the transient immune response, recovered horses are not protected and thus are prone to subsequent re‐infection. Immunity is not long lived after experimental or natural infection, and as a result the development of an effective vaccine has remained a challenge. In this study viraemic cells were studied in a murine EHV‐1 infection model. Mice were infected intranasally and viraemic cells were studied on days three and five of infection (peak of infection). This study may help to identify the nature of viraemic cells and their role in the transient immune response to infection. Buffy coat cells were removed and stained with a fluorescent antibody test for EHV‐1 antigen, and lung specimens were subjected to transmission electron microscopy. Both techniques confirmed the presence of viraemic cells. These viraemic cells were further stained for EHV‐1 antigen and for CD4 or CD8 biomarkers and results are discussed re: possible identification of viraemic cells in a murine model and their role in transient immune responses.Support or Funding InformationSupported by Institutional Resources of the University of Cambridge, UK, the University of Health and Humanities, British Virgin Islands, the Einstein Institute, and University of Science, Arts & Technology, Montserrat BWI.