title: Whole inactivated equine influenza vaccine: Efficacy against a representative clade 2 equine influenza virus, IFNgamma synthesis and duration of humoral immunity.
abstract: Equine influenza (EI) is a serious respiratory disease of horses induced by the equine influenza virus (EIV). Surveillance, quarantine procedures and vaccination are widely used to prevent or to contain the disease. This study aimed to further characterise the immune response induced by a non-updated inactivated EI and tetanus vaccine, including protection against a representative EIV isolate of the Florida clade 2 sublineage. Seven ponies were vaccinated twice with Duvaxyn IE-T Plus at an interval of four weeks. Five ponies remained unvaccinated. All ponies were experimentally infected with the EIV strain A/eq/Richmond/1/07 two weeks after the second vaccination. Clinical signs of disease were recorded and virus shedding was measured after experimental infection. Antibody response and EIV-specific IFNgamma synthesis, a marker of cell-mediated immunity, were measured at different time points of the study. Vaccination resulted in significant protection against clinical signs of disease induced by A/eq/Richmond/1/07 and reduced virus shedding when challenged at the peak of immunity. Antigenic drift has been shown to reduce protection against EIV infection. Inclusion of a more recent and representative EIV vaccine strain, as recommended by the OIE expert surveillance panel on equine influenza vaccine, may maximise field protection. In addition, significant levels of EIV-specific IFNgamma synthesis by peripheral blood lymphocytes were detected in immunised ponies, which provided a first evidence of CMI stimulation after vaccination with a whole inactivated EIV. Duration of humoral response was also retrospectively investigated in 14 horses vaccinated under field condition and following the appropriate immunisation schedule, up to 599 days after first immunisation. This study revealed that most immunised horses maintained significant levels of cross-reactive SRH antibody for a prolonged period of time, but individual monitoring may be beneficial to identify poor vaccine responders.
authors.affiliation: Animal Health Trust, Centre for Preventive Medicine, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK. Electronic address: romain.paillot@aht.org.uk.
authors.forename: R
authors.initials: R
authors.lastname: Paillot
authors.affiliation: Animal Health Trust, Centre for Preventive Medicine, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK.
authors.forename: L
authors.initials: L
authors.lastname: Prowse
authors.affiliation: Animal Health Trust, Centre for Preventive Medicine, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK.
authors.forename: F
authors.initials: F
authors.lastname: Montesso
authors.affiliation: Eli Lilly and Company, 1301 South White River Parkway East, Indianapolis, IN 46225, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Huang
authors.affiliation: Elanco Animal Health, European Biological R&D Eli Lilly and Company Limited, Lilly House, Priestley Road, Basingstoke, Hampshire RG24 9NL, UK.
authors.forename: H
authors.initials: H
authors.lastname: Barnes
authors.affiliation: Elanco Animal Health, European Biological R&D Eli Lilly and Company Limited, Lilly House, Priestley Road, Basingstoke, Hampshire RG24 9NL, UK.
authors.forename: J
authors.initials: J
authors.lastname: Escala
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D000917:Antibody Formation / Q000276:immunology; D006734:Horse Diseases / Q000276:immunology* / Q000517:prevention & control*; D006736:Horses / Q000276:immunology*; D007111:Immunity, Cellular / Q000276:immunology; D056724:Immunity, Humoral / Q000276:immunology; D053123:Influenza A Virus, H3N8 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology; D007371:Interferon-gamma / Q000276:immunology; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D014611:Vaccination / Q000662:veterinary; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology; D017201:Virus Shedding / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated; D007371:Interferon-gamma