Comparative immune responses after vaccination with the formulated inactivated African horse sickness vaccine serotype 1 between naïve horses and pretreated horses with the live-attenuated African horse sickness vaccine

Vet World Vol.15 October-2022 Article-1

Research Article

Veterinary World, 15(10): 2365-2375

https://doi.org/10.14202/vetworld.2022.2365-2375

Narongsak Chaiyabutr^1,2, Suphot Wattanaphansak³, Rachod Tantilerdcharoen⁴, Surasak Akesowan⁵, Suraseha Ouisuwan⁵, and Darm Naraporn⁵

1. Department of Research and Development, Queen Saovabha Memorial Institute, Thai Red Cross Society, Bangkok, Thailand.
2. Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
3. Department of Veterinary Medicine, Faculty of Veterinary Science Chulalongkorn University, Bangkok, Thailand.
4. Veterinary Diagnostic Laboratory, Faculty of Veterinary Science Chulalongkorn University, Bangkok, Thailand.
5. Horse Farm and Laboratory Animal Breeding Centre, Queen Saovabha Memorial Institute, Thai Red Cross Society, Petchaburi, Thailand.

Background and Aim: African horse sickness (AHS) is a non-contagious, high mortality, and insect-borne disease caused by a double-stranded RNA virus from the genus Orbivirus. The study aimed to develop inactivated vaccines serotype 1 inactivated AHS vaccine (IAV) and to compare the effect of IAV on antibody responses in young naïve horses and adult horses pre-immunized with live-attenuated AHS virus (AHSV) serotypes 1, 3, and 4 live-attenuated vaccine (LAV).

Materials and Methods: A total of 27 horses were vaccinated in two trials. Twelve AHS naïve young horses and 15 adult horses were divided into three groups of 4 and 5 horses each, respectively. Horses in control Group 1 were treated with phosphate-buffered saline. Horses in Group 2 were subcutaneously vaccinated with 2 mL of formulated IAV with 10% Gel 01™ (Seppic, France) on day 0 and horses in Group 3 were subcutaneously vaccinated with 2 mL of IAV on day 0 and a booster on day 28. The IAV vaccine was prepared by isolating the AHSV serotype 1 growing on Vero cells, 10× virus titer was concentrated by ultrafiltration and chemically killed by formalin, using 10% Gel 01™ as an adjuvant. Ethylenediaminetetraacetic acid blood samples were taken for hematology, blood biochemistry, and antibody titers using an immunoperoxidase monolayer assay on 158th day post-vaccination.

Results: Vaccination with IAV serotype 1 in adult horses pretreated with LAV increased antibody titers more than in young naïve vaccinated horses. The total leukocyte count and %neutrophils significantly increased, while %lymphocytes and %eosinophils significantly decreased on day 1 after vaccination; no local reactions were observed at the site of injection in any group. All biochemical and electrolyte analyte values were within the normal range after vaccination.

Conclusion: The formulation of IAV serotype 1 using Gel 01™ as an adjuvant is safe and induces high antibody titers. This IAV formulation induced a high antibody response in horses without causing local reactions and mild systemic effects. However, AHS naïve horses still required ≥2 vaccinations and an annual booster vaccination to achieve high antibody titers. Keywords: African horse sickness, inactivated vaccine, naïve young horse.

Keywords: African horse sickness, inactivated vaccine, naïve young horse.

How to cite this article: Chaiyabutr N, Wattanaphansak S, Tantilerdcharoen R, Akesowan S, Ouisuwan S, Naraporn D (2022) Comparative immune responses after vaccination with the formulated inactivated African horse sickness vaccine serotype 1 between naïve horses and pretreated horses with the live-attenuated African horse sickness vaccine, Veterinary World, 15(10): 2365–2375.

Received: 20-05-2022 Accepted: 23-08-2022 Published online: 07-10-2022

Corresponding author: Narongsak Chaiyabutr and Suphot Wattanaphansak E-mail: narongsak.c@chula.ac.th and supot.w@chula.ac.th

DOI: 10.14202/vetworld.2022.2365-2375

Copyright: Chaiyabutr, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.