Vaccination of foals with a modified live, equid herpesvirus-1 gM deletion mutant (RacHΔgM) confers partial protection against infection

Kydd, Julia H.; Hannant, Duncan; Robinson, Robert S.; Bryant, Neil; Osterrieder, Nikolaus

Abstract

Equid herpesvirus-1 (EHV-1) causes respiratory and neurological disease and late gestation abortion in pregnant mares. Current vaccines contain either inactivated or live EHV-1, but fail to provide complete clinical or virological protection, namely prevention of nasopharyngeal shedding and cell-associated viraemia. Thus, the development of novel products, such as modified live virus (MLV) vaccines which stimulate virus-specific, humoral and cell mediated immune responses more effectively remains a priority. Two groups of weaned foals (n = 6 each group) were used in a longitudinal, prospective, experimental study to evaluate immune responses elicited by two vaccinations with a glycoprotein M (gM) deletion mutant of EHV-1 (RacHdeltagM). Following two concurrent intranasal and intramuscular inoculations six weeks apart, vaccinated (8.4 ± 0.2 months old) and control foals (6.2 ± 0.4 months) were challenge infected intranasally with EHV-1 Ab4/8 four weeks after the second vaccination and clinical signs and virological replication measured. Vaccination caused no adverse events, but did stimulate significantly higher complement fixing and virus neutralizing antibodies in serum compared with control foals at either equivalent or pre-vaccination time points. Virus-specific nasopharyngeal antibody levels and cytotoxic T lymphocyte responses were not significantly different between the groups. Following challenge infection, these immune responses were associated with a reduction in clinical signs and virological replication in the vaccinated foals, including a reduction in duration and magnitude of pyrexia, nasopharyngeal shedding and cell-associated viraemia. We conclude that the RacHΔgM MLV primed EHV-1-specific humoral immune responses in weaned foals. However, complete virological protection by vaccination against EHV-1 requires further research.

Citation

Kydd, J. H., Hannant, D., Robinson, R. S., Bryant, N., & Osterrieder, N. (2020). Vaccination of foals with a modified live, equid herpesvirus-1 gM deletion mutant (RacHΔgM) confers partial protection against infection. Vaccine, 38(2), 388-398. https://doi.org/10.1016/j.vaccine.2019.09.106

• Journal Article Type: Article
• Acceptance Date: Sep 27, 2019
• Online Publication Date: Oct 16, 2019
• Publication Date: Jan 10, 2020
• Deposit Date: Oct 4, 2019
• Publicly Available Date: Oct 17, 2020
• Journal: Vaccine
• Print ISSN: 0264-410X
• Electronic ISSN: 1873-2518
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 38
• Issue: 2
• Pages: 388-398
• DOI: https://doi.org/10.1016/j.vaccine.2019.09.106
• Keywords: Equine, Equid herpesvirus-1, Vaccine, Deletion mutant, Immune response
• Public URL: https://nottingham-repository.worktribe.com/output/2747487
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0264410X1931360X
• Additional Information: This article is maintained by: Elsevier; Article Title: Vaccination of foals with a modified live, equid herpesvirus-1 gM deletion mutant (RacHΔgM) confers partial protection against infection; Journal Title: Vaccine; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.vaccine.2019.09.106; Content Type: article; Copyright: © 2019 Elsevier Ltd. All rights reserved.
• Contract Date: Oct 4, 2019