Efficacy and duration of immunity of a combined equine influenza and equine herpesvirus vaccine against challenge with an American-like equine influenza virus (A/equi-2/Kentucky/95).
Abstract: It has been recommended that modern equine influenza vaccines should contain an A/equi-1 strain and A/equi-2 strains of the American and European-like subtype. We describe here the efficacy of a modern updated inactivated equine influenza-herpesvirus combination vaccine against challenge with a recent American-like isolate of equine influenza (A/equine-2/Kentucky/95 (H3N8). The vaccine contains inactivated Influenza strains A-equine-1/Prague'56, A-equine-2/Newmarket-1/'93 (American lineage) and A-equine-2/ Newmarket-2/93 (Eurasian lineage) and inactivated EHV-1 strain RacH and EHV-4 strain V2252. It is adjuvanted with alhydrogel and an immunostim. Horses were vaccinated at the start of the study and 4 weeks later. Four, six and eight weeks after the first vaccination high anti-influenza antibody titres were found in vaccinated horses, whereas at the start of the study all horses were seronegative. After the challenge, carried out at 8 weeks after the first vaccination, nasal swabs were taken, rectal temperatures were measured and clinical signs were monitored for 14 days. In contrast to unvaccinated control horses, vaccinated animals shed hardly any virus after challenge, and the appearance of clinical signs of influenza such as nasal discharge, coughing and fever were reduced in the vaccinated animals. Based on these observations, it was concluded that the vaccine protected against clinical signs of influenza and, more importantly, against virus excretion induced by an American-like challenge virus strain. In a second experiment the duration of the immunity induced by this vaccine was assessed serologically. Horses were vaccinated at the start of the study and 6 and 32 weeks later. Anti-influenza antibody titres were determined in bloodsamples taken at the first vaccination, and 2, 6, 8, 14, 19, 28, 32, 37, 41, 45 and 58 weeks after the first vaccination. Vaccinated horses had high anti-influenza antibody titres, above the level for clinical protection against influenza, against all strains present in the vaccine until 26 weeks after the third vaccination.
Publication Date: 2004-02-21 PubMed ID: 14975389DOI: 10.1016/S1090-0233(03)00028-5Google Scholar: Lookup
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- Clinical Trial
- Controlled Clinical Trial
- Journal Article
Summary
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The study explores the effectiveness and longevity of an equine influenza-herpesvirus combination vaccine aimed at preventing diseases caused by the American-like strain of equine influenza virus. It concludes that this vaccine provides significant protection from the virus and clinical symptoms of influenza and maintains immunity in horses for at least 26 weeks post third vaccination.
About the Vaccine
- The vaccine, aimed at preventing diseases caused by A/equine-2/Kentucky/95 (H3N8) – an American subtype of equine influenza virus, contains inactivated strains of A-equine-1/Prague’56, A-equine-2/Newmarket-1/’93 (American lineage), A-equine-2/ Newmarket-2/93 (Eurasian lineage) and inactivated strains of Equine Herpes Virus (EHV) – 1 (RacH) and EHV-4 (V2252).
- Further, to stimulate a robust immune response, the vaccine is adjuvanted with alhydrogel and an immunostimulant.
Vaccine Efficacy
- The research commenced with the vaccination of horses at the start of the study, and again, four weeks later.
- During the course of the research, horses were examined at weeks 4, 6, and 8 post the first vaccination. The vaccinated horses displayed considerably high anti-influenza antibody titres during these three instances.
- A significant observation was that all horses at the start of the test were seronegative, i.e., they had no detectable antibodies against the virus in their blood
- After giving the challenge dose (exposure to the virus) at 8 weeks post the first vaccination, the researchers compared the symptoms in vaccinated horses with unvaccinated ones for a period of 14 days.
- They found that compared to the control group, the vaccinated horses shed almost no virus. Additionally, the vaccinated group showed highly reduced signs of influenza-like symptoms such as nasal discharge, coughing, and fever.
- Based on these findings, the researchers concluded that the vaccine was highly effective in protecting horses against the clinical symptoms of influenza and, most importantly, against the shedding of the American-like challenge virus strain.
Duration of Immunity
- In order to establish the longevity of the developed immunity, a second experiment was conducted where horses were vaccinated at the start, at six weeks, and then 32 weeks later.
- Blood samples were taken at specified intervals to determine anti-influenza antibody titres.
- Vaccinated horses displayed high anti-influenza antibody titres, indicating a solid immune response against all strain present in the vaccine up until 26 weeks after the third vaccination, suggesting that the vaccine provides a good deal of protection for at least 26 weeks post-vaccination.
Cite This Article
APA
Heldens JG, Pouwels HG, van Loon AA.
(2004).
Efficacy and duration of immunity of a combined equine influenza and equine herpesvirus vaccine against challenge with an American-like equine influenza virus (A/equi-2/Kentucky/95).
Vet J, 167(2), 150-157.
https://doi.org/10.1016/S1090-0233(03)00028-5 Publication
Researcher Affiliations
- Department of Virological R&D, Intervet International BV, P.O. Box 31, 5830 AA Boxmeer, The Netherlands. jacco.heldens@intervet.com
MeSH Terms
- Animals
- Animals, Newborn
- Herpesviridae Infections / immunology
- Herpesviridae Infections / prevention & control
- Herpesviridae Infections / veterinary
- Herpesvirus 4, Equid / immunology
- Horse Diseases / immunology
- Horse Diseases / prevention & control
- Horses
- Influenza A virus / immunology
- Orthomyxoviridae Infections / immunology
- Orthomyxoviridae Infections / prevention & control
- Orthomyxoviridae Infections / veterinary
- Vaccines, Combined / immunology
- Viral Vaccines / immunology
Citations
This article has been cited 4 times.- Pavulraj S, Eschke K, Theisen J, Westhoff S, Reimers G, Andreotti S, Osterrieder N, Azab W. Equine Herpesvirus Type 4 (EHV-4) Outbreak in Germany: Virological, Serological, and Molecular Investigations.. Pathogens 2021 Jun 25;10(7).
- Singh RK, Dhama K, Karthik K, Khandia R, Munjal A, Khurana SK, Chakraborty S, Malik YS, Virmani N, Singh R, Tripathi BN, Munir M, van der Kolk JH. A Comprehensive Review on Equine Influenza Virus: Etiology, Epidemiology, Pathobiology, Advances in Developing Diagnostics, Vaccines, and Control Strategies.. Front Microbiol 2018;9:1941.
- Bryant NA, Paillot R, Rash AS, Medcalf E, Montesso F, Ross J, Watson J, Jeggo M, Lewis NS, Newton JR, Elton DM. Comparison of two modern vaccines and previous influenza infection against challenge with an equine influenza virus from the Australian 2007 outbreak.. Vet Res 2010 Mar-Apr;41(2):19.
- Patel JR, Heldens JG. Immunoprophylaxis against important virus disease of horses, farm animals and birds.. Vaccine 2009 Mar 13;27(12):1797-1810.
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