RNA Vaccine Against EHV-1

Development of an RNA vaccine that provides protection from EHV-1 infection and its complications Research Plan: 1. Hypothesis and Specific Aims Like all herpesviruses, equine herpesviruses have evolved to modulate the host’s immune response and establish latency, which has made the development of effective vaccines extremely challenging. There are only a few examples of successful immunization strategies against herpesvirus infections, such as those against Marek’s disease in chickens and varicella zoster in humans. However, even those vaccines do not induce sterile immunity. The most important equine herpesvirus is type 1 (EHV-1), which infects horses via the respiratory tract and then establishes viremia. This can lead to epidemic abortions or the development of equid herpesvirus- associated myeloencephalopathy (EHM). Outbreaks of EHM can have a significant welfare and economic impact as evidenced by the Ogden, UT, or Valencia, Spain, outbreaks in 2011 and 2021, respectively. Despite the availability of commercial EHV-1 vaccines, there is no evidence that they provide sufficient protection against EHM and there is a critical need to develop new and more potent EHV-1 vaccines. Our long-term goal is to develop vaccines that will prevent EHV-1 infection and EHV-1-associated disease. The goal of this application is to exploit innovations in mRNA vaccine technology. We will identify and refine the most effective mRNA vaccine technology for immunization of horses and evaluate strategies that are based on conventional mRNA technology and replicon (self-amplifying RNA, saRNA) technology in combination with modern adjuvants. These mRNA vaccines will be designed to elicit targeted equine immune responses against the most important EHV-1 antigenic targets, specifically: 1) glycoprotein D (gD) which plays a central role in EHV-1 binding to its receptor on the cell surface and cellular entry; and 2) the immediate early (IE) protein, which was shown to elicit protective cellular immunity by our group. Ultimately, we will determine the efficacy of these novel, mRNA based EHV-1 vaccines in our well-established clinical EHM model. This animal model will be used to demonstrate efficacy of vaccines against EHV-1 infection including EHM in the horse. Our hypothesis is that novel EHV-1 nucleic acid vaccines and associated delivery systems will generate systemic and local immune responses that will prevent the occurrence of clinical EHV-1 disease including EHM. 1 Development of an RNA vaccine that provides protection from EHV-1 infection and its complications University of Kentucky BUDGET SUMMARY FOR ENTIRE PROPOSED GRANT PERIOD Budget Category 1st Year 2nd Year 3rd year Totals Personnel (Salary & Fringe $13,097 $26,816 $0 $39,913 Benefits) $25,783 $51,568 $0 $0 Consultant Costs $77,351 Supplies *Domestic Travel $2,500 $0 $0 $2,500 Other Expenses $19,467 $38,933 $0 $58,400 $60,847 $117,317 $0 $178,164 Total direct for Entire Proposed $4,775 $9550 $0 $14,325 Period Indirect cost Total for Entire Proposed Period $65,622 $126,867 $0 $192,489 *The Foundation will fund domestic travel to a meeting to present the results of this research, and will cover publication costs, not to exceed $2,000 (for both travel and publication), and only in the last year of the grant. BUDGET JUSTIFICATION Personnel: The PI Dr. Soboll Hussey has worked for >20 years studying equine immune responses to EHV-1 and has extensive experience studying equine immunology, EHV-1 infection procedures and well-developed challenge models. The Co-PI Dr. Goehring has extensive experience in the field of equine medicine, EHV-1 - host interaction and pathophysiology and EHM. The Co-PI Dr. Osterrieder is a world renown expert in herpesvirology and molecular virology and will work with the Co-PI Dr. Richt at KSU to generate the vaccine preparations and preform preliminary testing aided by the consultant Dr. Anna Blakney. No funding is requested for any of the principal/co-investigator’s salaries. No funding is requested for a graduate student. Funding is requested for a post-doc’s salary (21% for the funding period), and for 2 undergraduate students (20 hours/week). All will realize sample collection and handling as well as the in-house analysis. There will be no salary expense for Co-PI, post doc, graduate student when participating in studies at MSU. We request travel monies of $2,500 to travel between the 2 facilities (MSU and UK). These are listed under ‘domestic travel’. Supplies and Operating Expenses: Supply cost related to experimental work conducted at UK in the PI laboratory in year 1 and 2 of the proposal: Measurement of antibody responses and cytokines (SN, ELISA, CFT (sentinel), multiplex): $12,800 EHV-1/ -4 qPCR (surveillance): $21,000 2 Development of an RNA vaccine that provides protection from EHV-1 infection and its complications Reagents for skin biopsies and analysis and IHC (5 occasions in 88horses): $12,900 Paxgenetubes and molecular reagents for Interferon and cytokine mRNA expression analysis: $29,870 Operating expenses: hazardous waste fee (UK): $781 Animals: adult horses will come from the pool of healthy horses at UK North Farm. They will be not vaccinated for EHV-1/-4 for more than 18 months. For the pilot study in aim 3 we’ll plan on 18 horses (room and board for 40 days), and on 88 horses in the main study for 72 days ($5,800 and 52,600, respectively). After the study, horses will return to the main herd. Domestic Travel: $2,500 will be applied for travel between the 2 facilities (MSU and UK). FOREIGN TRAVEL: N/A Indirect Costs: 10% on total direct costs excluding personnel costs have been budgeted annually. 3