Equine influenza vaccine containing older H3N8 strains offers protection against A/eq/South Africa/4/03 (H3N8) strain in a short‐term vaccine efficacy study

Daly, Janet M.; Sindle, T.; Tearle, J.P.; Barquero, N.; Newton, J. R.; Corning, S.

doi:10.2746/042516407x180327

Cited by 19 publications

(20 citation statements)

References 14 publications

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“…It was shown to significantly reduce clinical signs and to prevent virus shedding in ponies after experimental infection with A/eq/South Africa/4/03 2 weeks post second vaccination (V2) [8, 29]. A/eq/South Africa/4/03 was isolated from the large 2003 outbreak in naïve horses in South Africa and is representative of the Florida sublineage clade 1 viruses.…”

Section: Introductionmentioning

confidence: 99%

Comparison of two modern vaccines and previous influenza infection against challenge with an equine influenza virus from the Australian 2007 outbreak

et al. 2009

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During 2007, large outbreaks of equine influenza (EI) caused by Florida sublineage Clade 1 viruses affected horse populations in Japan and Australia. The likely protection that would be provided by two modern vaccines commercially available in the European Union (an ISCOM-based and a canarypox-based vaccine) at the time of the outbreaks was determined. Vaccinated ponies were challenged with a representative outbreak isolate (A/eq/Sydney/2888-8/07) and levels of protection were compared. A group of ponies infected 18 months previously with a phylogenetically-related isolate from 2003 (A/eq/South Africa/4/03) was also challenged with the 2007 outbreak virus. After experimental infection with A/eq/Sydney/2888-8/07, unvaccinated control ponies all showed clinical signs of infection together with virus shedding. Protection achieved by both vaccination or long-term immunity induced by previous exposure to equine influenza virus (EIV) was characterised by minor signs of disease and reduced virus shedding when compared with unvaccinated control ponies. The three different methods of virus titration in embryonated hens’ eggs, EIV NP-ELISA and quantitative RT-PCR were used to monitor EIV shedding and results were compared. Though the majority of previously infected ponies had low antibody levels at the time of challenge, they demonstrated good clinical protection and limited virus shedding. In summary, we demonstrate that vaccination with current EIV vaccines would partially protect against infection with A/eq/Sydney/2888-8/07-like strains and would help to limit the spread of disease in our vaccinated horse population.

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Section: Introductionmentioning

confidence: 99%

Comparison of two modern vaccines and previous influenza infection against challenge with an equine influenza virus from the Australian 2007 outbreak

et al. 2009

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“…Infection in individuals with partial immunity can lead to virus shedding, can occur in vaccinated animals in the absence of clinical signs, and is more likely to occur if the vaccine strain is antigenically dissimilar to the infecting isolate (8,26,27). Animal challenge studies are considered the gold standard to test the degree of clinical protection afforded by vaccine strains in horses (7,12).…”

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confidence: 99%

Antigenic and Genetic Evolution of Equine Influenza A (H3N8) Virus from 1968 to 2007

Lewis

Daly

Russell

et al. 2011

J Virol

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Equine influenza virus is a major respiratory pathogen in horses, and outbreaks of disease often lead to substantial disruption to and economic losses for equestrian industries. The hemagglutinin (HA) protein is of key importance in the control of equine influenza because HA is the primary target of the protective immune response and the main component of currently licensed influenza vaccines. However, the influenza virus HA protein changes over time, a process called antigenic drift, and vaccine strains must be updated to remain effective. Antigenic drift is assessed primarily by the hemagglutination inhibition (HI) assay. We have generated HI assay data for equine influenza A (H3N8) viruses isolated between 1968 and 2007 and have used antigenic cartography to quantify antigenic differences among the isolates. The antigenic evolution of equine influenza viruses during this period was clustered: from 1968 to 1988, all isolates formed a single antigenic cluster, which then split into two cocirculating clusters in 1989, and then a third cocirculating cluster appeared in 2003. Viruses from all three clusters were isolated in 2007. In one of the three clusters, we show evidence of antigenic drift away from the vaccine strain over time. We determined that a single amino acid substitution was likely responsible for the antigenic differences among clusters.

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“…Review of these studies revealed that both our monovalent and multivalent DNA vaccines are potentially comparable in terms of immunogenicity and protection, although DNA vaccines showed a slightly delayed onset of immunity compared to modified live and canarypox-vectored vaccines (26). Specifically, SRH responses were similar to those elicited by licensed inactivated vaccines (Duvaxyn IE-T Plus and EQUIP F) (10, 14). Based on other studies, an SRH titer of roughly 150mm 2 is expected to be adequate for short-term protection against a homologous EI challenge (13).…”

Section: Discussionmentioning

confidence: 61%

“…Current inactivated, whole-virus vaccines have been shown to protect horses from equine influenza by reducing clinical signs and virus excretion (13, 14, 38, 40). However, outbreaks of equine flu continue to occur despite vaccination, due to mismatching between vaccine strains and circulating viruses (12, 13).…”

Section: Discussionmentioning

confidence: 99%

“…Serological data in the current study were compared to previous studies of modified live virus (8, 9, 34, 57), inactivated (10, 14, 21, 22, 32, 46), and pox-vectored (17, 36, 45, 54) equine influenza vaccines. Review of these studies revealed that both our monovalent and multivalent DNA vaccines are potentially comparable in terms of immunogenicity and protection, although DNA vaccines showed a slightly delayed onset of immunity compared to modified live and canarypox-vectored vaccines (26).…”

Section: Discussionmentioning

confidence: 99%

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

Ault¹,

Zajac²,

Kong³

et al. 2012

Vaccine

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Equine influenza vaccine containing older H3N8 strains offers protection against A/eq/South Africa/4/03 (H3N8) strain in a short‐term vaccine efficacy study

Abstract: When variant strains of equine influenza virus first emerge, booster immunisations with currently available vaccines may limit infection provided sufficiently high antibody levels are achieved, suggesting that vaccination in the face of an outbreak may be beneficial.

Cited by 19 publications

References 14 publications

Comparison of two modern vaccines and previous influenza infection against challenge with an equine influenza virus from the Australian 2007 outbreak

Comparison of two modern vaccines and previous influenza infection against challenge with an equine influenza virus from the Australian 2007 outbreak

Antigenic and Genetic Evolution of Equine Influenza A (H3N8) Virus from 1968 to 2007

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

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