Persistence of Anti-Rabies Antibody Response in Horses Following Vaccination

It would appear that after an initial rabies vaccine followed by the yearly booster vaccine every four years, it may be protective for 80 to 90 percent of the vaccinates. What to do with the non-responders remains a question. Perhaps testing for antibiotic response before booster, at least once, may be indicated. Before a recommendation can be made, further support of these findings should be done.
DrO

Persistence of Anti-Rabies Antibody Response in Horses Following Vaccination

Pathogens. 2024 Jan 28;13(2):125. doi: 10.3390/pathogens13020125.
Authors
Sharon Tirosh-Levy 1 2 , Leehe Shaiman Barom 1 , Shiri Novak 3 , Marina Eyngor 3 , Gili Schvartz 1 4 , Boris Yakobson 3 , Amir Steinman 1
Affiliations

1 Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel.
2 Division of Parasitology, Kimron Veterinary Institute, Beit Dagan 5020001, Israel.
3 WOAH Rabies Reference Laboratory, Kimron Veterinary Institute, Beit Dagan 5020001, Israel.
4 Department of Virology, Kimron Veterinary Institute, Beit Dagan 5020001, Israel.

PMID: 38392863
DOI: 10.3390/pathogens13020125

Abstract

Rabies is a fatal zoonotic disease affecting all mammalian species. It is caused by the rabies virus and is prevalent worldwide. Horses are not commonly infected with rabies but their vaccination is recommended due to the potential zoonotic risk. This study aimed to evaluate the duration of immunity following rabies vaccination in horses. A total of 126 serum samples were collected from 93 horses, vaccinated 6 to 91 months before sampling. Rabies-virus-neutralizing antibody (RVNA) levels were evaluated using the Rabies Fluorescent Focus Inhibition Test (RFFIT). A protective RVNA titer of above 0.5 IU/mL was found in 112 (88.9%) of the samples and 84 (90.3%) of the horses. Antibody titers declined over time (rho = -0.271, p = 0.002); however, there was no significant difference in antibody titers or the prevalence of unprotected horses between the time intervals following vaccination. Purebred horses had lower antibody titers (p = 0.024). The response to booster vaccination was inspected in ten horses, and increased antibody titers were found in eight of them. The results of this study demonstrate the prolonged persistence of protective immunity in horses following rabies vaccination, in some cases, for up to eight years. Therefore, the current annual vaccination strategy should be re-evaluated. A rate of 9.7% of poor responders should be considered from an epidemiological perspective in order to minimize the risk of emergence of the disease.

Keywords: RVNA; equine; horse; immunity; rabies; vaccine.