Dataset Information

Immunogenicity and clinical protection against equine influenza by DNA vaccination of ponies.

ABSTRACT: Equine influenza A (H3N8) virus infection is a leading cause of respiratory disease in horses, resulting in widespread morbidity and economic losses. As with influenza in other species, equine influenza strains continuously mutate, often requiring the development of new vaccines. Current inactivated (killed) vaccines, while efficacious, only offer limited protection against diverse subtypes and require frequent boosts. Research into new vaccine technologies, including gene-based vaccines, aims to increase the neutralization potency, breadth, and duration of protective immunity. Here, we demonstrate that a DNA vaccine expressing the hemagglutinin protein of equine H3N8 influenza virus generates homologous and heterologous immune responses, and protects against clinical disease and viral replication by homologous H3N8 virus in horses. Furthermore, we demonstrate that needle-free delivery is as efficient and effective as conventional parenteral injection using a needle and syringe. These findings suggest that DNA vaccines offer a safe, effective, and promising alternative approach for veterinary vaccines against equine influenza.

SUBMITTER: Ault A

PROVIDER: S-EPMC3474358 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Immunogenicity and clinical protection against equine influenza by DNA vaccination of ponies.

Ault Alida A Zajac Alyse M AM Kong Wing-Pui WP Gorres J Patrick JP Royals Michael M Wei Chih-Jen CJ Bao Saran S Yang Zhi-yong ZY Reedy Stephanie E SE Sturgill Tracy L TL Page Allen E AE Donofrio-Newman Jennifer J Adams Amanda A AA Balasuriya Udeni B R UB Horohov David W DW Chambers Thomas M TM Nabel Gary J GJ Rao Srinivas S SS

Vaccine 20120323 26

Equine influenza A (H3N8) virus infection is a leading cause of respiratory disease in horses, resulting in widespread morbidity and economic losses. As with influenza in other species, equine influenza strains continuously mutate, often requiring the development of new vaccines. Current inactivated (killed) vaccines, while efficacious, only offer limited protection against diverse subtypes and require frequent boosts. Research into new vaccine technologies, including gene-based vaccines, aims t ...[more]

PMID: 22449425

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Project description:Vaccination is one of the most effective tools for limiting the impact of equine influenza (EI). The humoral immunity established following a primary vaccination course can decrease significantly between the second (V2) and third immunisations (V3), leaving some horses insufficiently protected for several weeks. This so-called "immunity gap" poses a challenge to all EI vaccines. During this period, the EI infection of vaccinated animals may be followed by marked clinical signs and virus shedding. However, several EI vaccines have been shown to stimulate equine influenza virus (EIV)-specific cell-mediated immunity, which is likely to play a role in protection against EIV infection and/or mitigate the clinical and virological signs of EI. Reducing the interval between V2 and V3 has been shown to be counterproductive to longer-term immunity. Further research is needed to define and address the "immunity gap" in horses. This study aimed to measure the level of protection induced by a whole inactivated, ISCOMatrix adjuvanted, EI and tetanus vaccine (Equilis Prequenza-Te) when challenged during the immunity gap (i.e., immediately before the recommended boost immunisation, more than 5 months after V2) using infection with a recent heterologous Florida Clade 2 (FC2) equine influenza virus (EIV) strain. This vaccine was tested in a Welsh mountain pony model. A group of seven ponies was vaccinated twice, 4 weeks apart. The protective antibody response was measured and ponies were challenged, along with 5 unvaccinated control ponies, by experimental infection with the FC2 A/eq/Northamptonshire/1/13 EIV strain, 158 days (around 5.2 months) after V2 and their clinical signs and virus shedding were monitored. EI serology was measured by single radial haemolysis (SRH) and haemagglutination inhibition (HI). Clinical signs and virus shedding (measured by qRT-PCR and hen's egg titration) were compared with controls. All vaccinates had detectable, low SRH antibody titres and most had detectable, low HI titres. Significant clinical and virological protection was observed in vaccinates (p < 0.05), supporting the good performance of this vaccine against a recent EIV strain. In this study, the impact of the immunity gap in ponies was limited after primary vaccination with this whole inactivated, ISCOMatrix adjuvanted EI and tetanus vaccine (Equilis Prequenza-Te) when infected several months after V2 with a recent FC2 strain, which is representative of EIV circulating in the EU.

Project description:Every year, several epizooties of equine influenza (EI) are reported worldwide. However, no EI case has been identified in France between 2015 and late 2018, despite an effective field surveillance of the pathogen and the disease. Vaccination against equine influenza virus (EIV) remains to this day one of the most effective methods to prevent or limit EI outbreaks and the lack of detection of the pathogen could be linked to vaccination coverage. The aim of this study was to evaluate EI immunity and vaccine coverage in France through a large-scale serological study. A total of 3004 archived surplus serums from French horses of all ages, breeds and sexes were selected from four different geographical regions and categories (i.e., sanitary check prior to exportation, sale, breeding protocol or illness diagnosis). EIV-specific antibody response was measured by single radial hemolysis (SRH) and an EIV-nucleoprotein (NP) ELISA (used as a DIVA test). Overall immunity coverage against EIV infection (i.e., titers induced by vaccination and/or natural infection above the clinical protection threshold) reached 87.6%. The EIV NP ELISA results showed that 83% of SRH positive serum samples from young horses (≤3 years old) did not have NP antibodies, which indicates that the SRH antibody response was likely induced by EI vaccination alone (the HA recombinant canarypoxvirus-based EI vaccine is mostly used in France) and supports the absence of EIV circulation in French horse populations between 2015 and late 2018, as reported by the French equine infectious diseases surveillance network (RESPE). Results from this study confirm a strong EI immunity in a large cohort of French horses, which provides an explanation to the lack of clinical EI in France in recent years and highlights the success of vaccination against this disease. However, such EI protection has been challenged since late 2018 by the incursion in the EU of a Florida Clade 1 sub-lineage EIV (undetected in France since 2009), which is also reported here.

Dataset Information

Immunogenicity and clinical protection against equine influenza by DNA vaccination of ponies.

Publications

Immunogenicity and clinical protection against equine influenza by DNA vaccination of ponies.

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