Sero-Monitoring of Horses Demonstrates the Equivac® HeV Hendra Virus Vaccine to Be Highly Effective in Inducing Neutralising Antibody Titres

Kim Halpin,Kerryne Graham,Peter A Durr

doi:10.3390/vaccines9070731

Abstract

Hendra virus (HeV) is a high consequence zoonotic pathogen found in Australia. The HeV vaccine was developed for use in horses and provides a One Health solution to the prevention of human disease. By protecting horses from infection, the vaccine indirectly protects humans as well, as horses are the only known source of infection for humans. The sub-unit-based vaccine, containing recombinant HeV soluble G (sG) glycoprotein, was released by Pfizer Animal Health (now Zoetis) for use in Australia at the end of 2012. The purpose of this study was to collate post-vaccination serum neutralising antibody titres as a way of assessing how the vaccine has been performing in the field. Serum neutralization tests (SNTs) were performed on serum samples from vaccinated horses submitted to the laboratory by veterinarians. The SNT results have been analysed, together with age, dates of vaccinations, date of sampling and location. Results from 332 horses formed the data set. Provided horses received at least three vaccinations (consisting of two doses 3–6 weeks apart, and a third dose six months later), horses had high neutralising titres (median titre for three or more vaccinations was 2048), and none tested negative.

Highlights

Introduction and Richard BennettHendra virus is a zoonotic, high consequence pathogen for which the natural reservoir is the four species of flying fox (Pteropus bat species) found on mainland Australia and the primary spillover species is the horse, from which humans are secondarily infected [1].The virus emerged in Australia in 1994 in a racing stable in the Brisbane suburb of Hendra, where a number of thoroughbred horses developed a mysterious illness
This study consisted of equine serum samples submitted to Australian Centre for Disease Preparedness (ACDP) during 2014–2020 by veterinarians requesting the Hendra virus (HeV) Serum neutralization tests (SNTs) to ascertain neutralising antibody titre following a vaccination
Equivac® HeV Hendra virus vaccinations per horse with the count being the number of horses

Summary

Introduction

Introduction and Richard BennettHendra virus is a zoonotic, high consequence pathogen for which the natural reservoir is the four species of flying fox (Pteropus bat species) found on mainland Australia and the primary spillover species is the horse, from which humans are secondarily infected [1].The virus emerged in Australia in 1994 in a racing stable in the Brisbane suburb of Hendra, where a number of thoroughbred horses developed a mysterious illness. Hendra virus is a zoonotic, high consequence pathogen for which the natural reservoir is the four species of flying fox (Pteropus bat species) found on mainland Australia and the primary spillover species is the horse, from which humans are secondarily infected [1]. Thirteen horses died along with their noted trainer, Vic Rail. Another man, a strapper for Vic Rail, became infected but survived [2]. Five further outbreaks occurred between 1994 and 2004, and there have been annual spillover events consistently since 2006, with most events occurring in the cooler months. Most of these have involved single horses infected in an outdoor grazing environment.

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