JULY 2023 VOLUME 32, NO.3
A PUBLICATION BY: THE UNIVERSITY OF KENTUCKY DEPARTMENT OF VETERINARY SCIENCE, FUNDED BY:
MAXWELL H. GLUCK EQUINE RESEARCH CENTER. EQUUS / STANDARDBRED STATION, INC. M&J INSURANCE
I N T HI S I SSUE
GL UCK RE S E ARCH S P O T L I G H T
INTERNATIONAL Protective humoral immunity of Second Quarter 2023.......................2,3 The ridden horse checklist...............3,4 mares and their foals post equine
NATIONAL rotavirus A G3P[12] vaccination Unsanctioned Racing’s Role in Equine Our research laboratory is interested in Infectious Anemia (EIA) and Equine Piroplasmosis (EP) in the understanding, treating and preventing equine United States.....................................4,5 infectious diseases. One of our primary interests KENTUCKY is to better understand the genetic and antigenic Gastroduodenal ulceration syndrome diversity of equine rotavirus groups A and B. In in foals in central Kentucky from 2020 - 2022...........................................6 addition, we hope to characterize and identify PLEASE VISIT OUR WEBSITE correlates of protective immunity against rotavirus
infections in horses.
T H ANK YOU SPONSO RS!
Equine rotavirus A (ERVA) globally causes rotaviral diarrhea in foals and was first described in 1975. Two structural proteins, encoded by P and G genotypes, are recognized, of which G3, G14 and P[12] are the most common. Swift and intensive medical treatment typically prevents fatalities but represents a significant economic burden to the equine industry. Due to ERVA’s incredibly infectious nature, the high number of virus particles shed in fecal matter, its environmental stability, and the non-enveloped structure, ERVA is very hard to contain once an outbreak occurs, which can lead to a heavy burden on farm staff and veterinarians. Therefore, prevention through biosecurity measures, monitoring programs and vaccination is of the utmost importance. Before the introduction of the monovalent G3 vaccine by Zoetis in 1996, ERVA infection manifested as a disease of neonatal foals. Mares are vaccinated three times during pregnancy at 8, 9, and 10 months of gestation to generate a protective passive immunity to the foal through colostrum. Interestingly, rotaviral diarrhea attributable to ERVA can be observed in foals
between three and four months of age born to vaccinated mares and in neonates of unvaccinated dams. Foals at younger ages are much more susceptible to infection and develop more severe clinical signs. With intensive treatment, rotaviral diarrhea has a high survival rate of 94%. However, without treatment, ERVA can be rapidly fatal, especially in neonates. An ongoing collaborative research project at the University of Kentucky Gluck Equine Research Center is focused on whether vaccination against ERVA G3P[12] provides cross-protection against ERVA G14P[12], with an additional goal of monitoring the duration of maternallyderived protective antibodies. Serum samples were collected from mares pre-vaccination, post-vaccination and for multiple months postfoaling. Foal serum samples were collected prior to nursing and bi-weekly for up to seven months post foaling. Additionally, fecal swabs from both the foals and mares as well as colostrum and milk samples were collected. A total of 50 mare-foal pairs were included in this study, leading to a total of more than 1,500 samples. A virus neutralization assay was used to determine neutralizing antibody titers in serum against ERVA G3P[12] and ERVA G14P[12]. Based on preliminary data, vaccination of mares maintained and increased ERVA G3P[12] virus neutralizing titers. Importantly, serum antibodies were crossprotective against ERVA G14P[12]. Further, ERVA G3P[12] and ERVA G14P[12] neutralizing antibodies are passively transferred through the colostrum as pre-nursing neutralizing antibodies were undetectable and increased greatly in postnursing samples.
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