Our equine herpesvirus type 1 (EHV-1) work funded by the Harry M. Zweig Fund for Equine Research proceeding this project has focused on new vaccine candidate testing and host immune characterization upon infection and vaccination. The latter indicated that the early intranasal immune response of horses against EHV-1 infection is characterized by innate immune reactions composed of various inflammatory markers followed by specific adaptive immunity. We also found that the intranasal response to the virus is strikingly different in EHV-1 susceptible and protected horses. For example, susceptible horses express chemokines and type I interferon during the first week post infection. These inflammatory markers are completely absent in protected horses which, in contrary, have intranasal EHV-1 specific antibodies. Intranasal antibodies prevent clinical signs, viral shedding and viremia in the protected horse. This suggested that intranasal immune components are potent biomarkers for managing horses during EHV-1 outbreaks and resulted in the development of a new EHV-1 Immune Biomarker assay. However, the host immune analysis on the protein level is currently limited to the available protein detection tools.

Our hypothesis is that intranasal immune markers can distinguish between EHV-1 protected and susceptible horses and that a combination of these markers can be utilized to clearly determine the stage of infection with or immunity and protection against EHV-1, thereby assisting the management of horses in EHV-1 outbreaks and allowing the earlier release of protected horses from quarantine.

The specific aim of this project is to identify a comprehensive intranasal biomarker panel indicative for EHV-1 susceptibility and for host immunity and protection using a banked sample set from fully susceptible and fully protected horses.

The goal of this approach is to further characterize intranasal immunity in EHV-1 susceptible horses and those protected against infection. The new biomarker candidates identified during this project will advance future diagnostic tool development for host immunity against EHV1 and EHV-1 outbreak management.

The outcomes of this project are relevant to (i) more effectively manage EHV-1 outbreaks through the ability to distinguish susceptible and protected horses and informed decision making that significantly shortens quarantine of the latter group, (ii) to increase the knowledge on host immunity against EHV-1 in the respiratory tract which can guide the development of vaccines or vaccination protocols resulting in a protective host immune profile, and (iii) to overall prevent future EHV-1 and EHM outbreaks by increasing protection in the US horse population.