• Korean Journal of Veterinary Research
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• v.59 no.3
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• pp.151-155
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• 2019

Equine influenza (EI) is the main cause of respiratory illness in equines across the globe and is caused by equine influenza A virus (EIV-A), which has impacted the equine industry internationally because of the marginal mortality and high morbidity. In the present study, the immune responses after equine influenza vaccination were evaluated in 4,144 horses in Korea using the hemagglutination inhibition (HI) assay. The equine influenza virus (EIV), A/equine/South Africa/4/03 (H3N8), was used as the antigen in the HI assay. The mean seropositive rates were 89.2% (97.4% in 2016, 77.6% in 2017, and 92.4% in 2018). This paper highlights the advances in understanding the effects of vaccines and control strategies for mitigating the emerging menace by EIV.

• Journal of Animal Science and Technology
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• v.64 no.3
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• pp.588-598
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• 2022

Despite vaccination, equine influenza virus (EIV) and equine herpesvirus (EHV) infections still cause highly contagious respiratory diseases in horses. Recently, concurrent vaccination with EIV and EHV was suggested as a new approach; however, there have been no reports of concurrent vaccination with recombinant canarypox EIV and inactivated EHV vaccines. In this study, we aimed to compare the EIV-specific immune responses induced by concurrent administrations of a recombinant canarypox EIV vaccine and an inactivated bivalent EHV vaccine with those induced by a single recombinant canarypox EIV vaccine in experimental horse and mouse models. Serum and peripheral blood mononuclear cells (PBMCs) were collected from immunized animals after vaccination. EIV-specific serum antibody levels, serum hemagglutinin inhibition (HI) titers, and interferon-gamma (IFN-γ) levels were measured by enzyme-linked immunosorbent assay, HI assay, and quantitative polymerase chain reaction, respectively. Concurrent EIV and EHV vaccine administration significantly increased IFN-γ production, without compromising humoral responses. Our data demonstrate that concurrent vaccination with EIV and EHV vaccines can enhance EIV-specific cellular responses in horses.

• Korean Journal of Veterinary Service
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• v.43 no.2
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• pp.59-65
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• 2020

The aim of the study was to investigate the seroprevalence of equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4), equine influenza virus (EIV), and Streptococcus (S.) equi subspecies equi in the horse population of Jeju. Serum samples were taken from 71 horses, regularly vaccinated with EHV-1 and strangles twice (April and November) a year. In April 2014, seropositive rates of EHV-1 and strangles were 24.5% and 84.5%, while in November, were 26.8% and 62.0%, respectively. A total of 1,144 serum samples, including Jeju native horses, Halla horses, and Thoroughbred horses were collected from slaughter house for 4 years (2014 to 2017) and it is unclear the animals were vaccinated or not. The seropositive rates in Jeju was 21.9% (250/l,144) for EHV-1, 96.4% (1,103/1,144) for EHV-4, 14.6% (129/882) for EIV, and 79.3% (879/1,108) for strangles. The seropositive rate was the highest in Thoroughbred, but lowest in Hala horse.

• Korean Journal of Veterinary Service
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• v.46 no.4
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• pp.263-268
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• 2023

Despite regular vaccinations, equine influenza virus (EIV) and Streptococcus equi subsp. equi (strangles) are the cause of highly contagious respiratory infections in horses. Many recent studies have reported that the concurrent administration of two vaccines could simplify horse management and minimize veterinary expenses. However, there is little information available regarding the efficacy of concurrent vaccinations against EIV and strangles. In this study, we evaluated EIV-specific antibody responses following the single EIV vaccination with the recombinant viral-vectored EIV vaccine or concurrent vaccination with the EIV and inactivated strangles vaccines. Blood samples were collected at 1-, 2-, 4-, and 8 weeks post-immunization (wpi) from each group. EIV-specific antibodies were evaluated by enzyme-linked immunosorbent assay (ELISA) and hemagglutination inhibition (HAI) assay. Both single and concurrent vaccination showed similar levels of EIV-specific serum immunoglobulin g (IgG) at 1 and 2 wpi. However, at 4 to 8 wpi, the EIV-only vaccination group showed significantly higher serum IgG levels than those from the concurrently vaccinated group. The HAI titers showed similar trends as the ELISA data, except at 8 wpi when both groups presented HAI titers with no significant differences. These data demonstrate that the concurrent vaccination against EIV and strangles could compromise the humoral immune response to equine influenza between vaccination intervals, which suggests the use of the consecutive vaccination protocol for EIV and strangles rather than concurrent vaccination.

• Journal of Practical Agriculture & Fisheries Research
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• v.20 no.1
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• pp.89-96
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• 2018

The object of this study was to evaluate the change of antibody titers on virus strains after inoculation with commercial killed equine influenza (EI) vaccines in horses. Serum antibodies of 20 Thoroughbred yearlings were detected using hemagglutination inhibition test for 41 weeks. Second vaccination is inoculated 4 weeks after the initial vaccination. Most of antibody titers were not increased until 4 weeks after first vaccination. The highest titers were detected 6-10 weeks after vaccination. The titers were decreased slowly and maintained for 16 weeks after inoculation. We could barely detect the antibody 41 weeks after vaccination in most cases. Vaccine anergia were appeared in 3 horses (15%) but it depended on virus strains. A/Equine/La Plata/93(H3N8) strain that induce high and durable antibody responses was the most effective among three strains. This study presents the first comprehensive data on the endurance of antibody titers against EI. Our data also suggests that yearlings should be inoculated three times in order to maintaining optimal antibody titers against EI. We speculate the causes of anergia were vaccine break down or individual specificity. Further research is needed to investigate immunological unresponsiveness. This was the first study on strain of equine vaccine in Korea.

• Journal of Microbiology and Biotechnology
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• v.25 no.3
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• pp.317-320
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• 2015

H3N8 equine influenza virus (EIV) causes respiratory diseases in the horse population, and it has been demonstrated that EIV can transmit into dogs owing to its availability on receptors of canine respiratory epithelial cells. Recently, we isolated H3N8 EIV from an EIV-vaccinated horse that showed symptoms of respiratory disease, and which has a partially truncated nonstructural gene (NS). However, it is not clear that the NS-truncated EIV has an ability to cross the host species barrier from horses to dogs as well. Here, we experimentally infected the NS-truncated H3N8 EIV into dogs, and monitored their clinical signs and viral load in respiratory organs to determine the virus's transmissibility.