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Heterologous prime boost vaccination against West Nile virus in horses

Abstract
In Europe, West Nile virus is an emerging mosquito-borne flavivirus with metazoonotic potential. While the virus depends on an enzootic life cycle in birds and competent arthropod vectors (mainly Culex species), horses and humans serve as accidental dead-end hosts. A subset of horses infected with West Nile virus develops neuroinvasive disease which is frequently life-threatening in naïve animals. Several effective vaccine types against lineage 2 West Nile virus prevailing in Europe, are licensed for horses. The immunity of horses and duration of neutralizing antibody response against WNV lineage 2 in response to vaccination, is however not extensively evaluated. For effective immunization usually sequential vaccinations in the form of prime-boost are required and traditionally consist of homologous boosts. Because of practicability, practitioners frequently choose a heterologous prime-boost approach which is not investigated for efficacy in horses in the case of immunization against lineage 2 WNV. The aims of this proposed study are to compare different prime-boost vaccinations against WNV in horses (homologous inactivated virus prime-boost, homologous recombinant canarypox vector prime-boost, canarypox prime- inactivated boost, and inactivated prime- canarypox boost) in regard to their induced immune response. Thus, the humoral immune response will be quantified using WNV neutralizing antibody titres against lineage 1 and 2. Results of this study will provide a better insight into the immune response against the less investigated WNV lineage 2 and answer questions that are highly relevant to daily equine veterinary practice: whether the sequential administration of differing vaccine types still gives an anamnestic immune response against the currently in Europe dominating WNV lineage 2 strains. Thus, vaccination schedules against WNV in endemic areas can be improved.
Lemma
Heterologous prime boost vaccination against WNV
Project leader
de Heus Phebe
Duration
01.02.22-30.09.24
Type of Research
Clinical research / study
Vetmed Research Units
University Equine Clinic, Clinical Unit of Equine Internal Medicine
Funded by
Stiftung Pro Pferd, Zürich, Switzerland
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