African Horse Sickness Fever in Vaccinated Horses: Short Communication

Wernery, Ulrich; Joseph, Sunitha; Raghavan, R.; Dyer, Bimbi; Spendrup, S.

doi:10.1016/j.jevs.2020.102967

Cited by 7 publications

(8 citation statements)

References 7 publications

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“…The results of the present study show that three immunisations per year with an inactivated vaccine containing nine serotypes in one injection are necessary for the development of high levels of ELISA and virus neutralising antibodies. Similar results were achieved by Rodriguez et al 30 and Wernery et al 4 who immunised horses with all nine AHS serotypes in two injections (injection 1 ‐ serotypes 1, 4, 7 and 9 and injection 2 ‐ serotypes 2, 3, 5 and 6). In their investigations, it was also shown that it seems to be an advantage to immunise horses with the CVRL vaccine that had been previously vaccinated with the attenuated Onderstepoort biological products (OBP) vaccine from Onderstepoort, South Africa, as these horses produced higher virus neutralising and ELISA antibodies than horses that had not received the OBP vaccine.…”

Section: Discussionsupporting

confidence: 84%

Humoral antibody response of 10 horses after vaccination against African horse sickness with an inactivated vaccine containing all 9 serotypes in one injection

Wernery

Rodrı́guez

Raghavan

et al. 2020

Equine Veterinary Journal

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Background African horse sickness (AHS) is a devastating viral disease of equids that was first recorded in 1327. Currently, prevention and control of the disease are based on attenuated vaccines and midge control. It has been shown that attenuated Orbivirus vaccines are not always safe as they may reverse to virulence. Objectives In the Emirate of Dubai, a vaccination experiment was carried out with an inactivated AHS vaccine produced at the Central Veterinary Research Laboratory (CVRL), Dubai, UAE to investigate the humoral antibody response of AHS‐naïve horses to this vaccine. Our vaccination experiment was performed to establish an AHS vaccine bank in the UAE to protect horses from the disease in case of an outbreak. Therefore, CVRL established an inactivated AHS vaccine containing all nine serotypes which induce high neutralising antibodies. Study design A total of 10 horses kept in a desert isolation area were subcutaneously and intramuscularly vaccinated with an inactivated vaccine containing all nine AHS serotypes previously isolated from Kenyan horse fatalities. Primary immunisation was followed by two booster immunisations 4 weeks and 6 months apart. After 13 months, an annual booster was administered. Methods Blood samples were regularly withdrawn for ELISA and virus neutralisation testing. Additionally, EDTA blood was tested every second day for 14 days post each vaccination for the presence of AHS virus or its RNA. Results Results show that ELISA and virus neutralising antibodies appeared after the first booster, declined after 4‐6 months and therefore three vaccinations and an annual vaccination are necessary to achieve high protective virus neutralising antibodies. Main limitations No challenge infection was carried out due to the lack of a safe facility in the UAE. Conclusion Before more advanced AHS vaccines become a reality, inactivated vaccines containing all nine serotypes should be used as they produce high ELISA and neutralising antibodies.

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Section: Discussionsupporting

confidence: 84%

Humoral antibody response of 10 horses after vaccination against African horse sickness with an inactivated vaccine containing all 9 serotypes in one injection

Wernery

Rodrı́guez

Raghavan

et al. 2020

Equine Veterinary Journal

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“…Several months later, six vaccinated horses showed mild clinical signs of AHS with swollen orbital, fever, increased heart rate and respiration. The horses had developed horse sickness fever, but they all survived, and the clinical signs receded within 72 h [31]. No live virus was isolated from their EDTA blood, but PCR was positive for serotypes 9 (4x), 4 (1x) and 1 (1x) when analysed at CVRL.…”

Section: Discussionmentioning

confidence: 99%

Immune response of horses to inactivated African horse sickness vaccines

et al. 2020

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Background: African horse sickness (AHS) is a serious viral disease of equids resulting in the deaths of many equids in sub-Saharan Africa that has been recognized for centuries. This has significant economic impact on the horse industry, despite the good husbandry practices. Currently, prevention and control of the disease is based on administration of live attenuated vaccines and control of the arthropod vectors. Results: A total of 29 horses in 2 groups, were vaccinated. Eighteen horses in Group 1 were further divided into 9 subgroups of 2 horses each, were individually immunised with one of 1 to 9 AHS serotypes, respectively. The eleven horses of Group 2 were immunised with all 9 serotypes simultaneously with 2 different vaccinations containing 5 serotypes (1, 4, 7-9) and 4 serotypes (2, 3, 5, 6) respectively. The duration of this study was 12 months. Blood samples were periodically withdrawn for serum antibody tests using ELISA and VNT and for 2 weeks after each vaccination for PCR and virus isolation. After the booster vaccination, these 27 horses seroconverted, however 2 horses responded poorly as measured by ELISA. In Group 1 ELISA and VN antibodies declined between 5 to 7 months post vaccination (pv). Twelve months later, the antibody levels in most of the horses decreased to the seronegative range until the annual booster where all horses again seroconverted strongly. In Group 2, ELISA antibodies were positive after the first booster and VN antibodies started to appear for some serotypes after primary vaccination. After booster vaccination, VN antibodies increased in a different pattern for each serotype. Antibodies remained high for 12 months and increased strongly after the annual booster in 78% of the horses. PCR and virus isolation results remained negative. Conclusions: Horses vaccinated with single serotypes need a booster after 6 months and simultaneously immunised horses after 12 months. Due to the non-availability of a facility in the UAE, no challenge infection could be carried out.

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“…The present results would support a previous study showing that horses vaccinated with single serotypes need a booster after 6 months and simultaneously immunized horses need it after 12 months [ 29 ], even if inactivated Orbivirus vaccines are safe, as the virus does not revert to virulence or cause viremia in vaccinated animals or reassort with field Orbivirus strains [ 30 ]. However, recent research has shown that multiple vaccinations with IAV containing all nine serotypes did not prevent AHSV in approximately 10% of vaccinated horses despite high neutralizing antibodies [ 31 ].…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2022

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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.

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African Horse Sickness Fever in Vaccinated Horses: Short Communication

Cited by 7 publications

References 7 publications

Humoral antibody response of 10 horses after vaccination against African horse sickness with an inactivated vaccine containing all 9 serotypes in one injection

Humoral antibody response of 10 horses after vaccination against African horse sickness with an inactivated vaccine containing all 9 serotypes in one injection

Immune response of horses to inactivated African horse sickness vaccines

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

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