Name
Immunogenicity and efficacy of a Newcastle disease virus vectored vaccine against highly pathogenic avian influenza in poultry and mammals
Presenter
Alex Leacy, University of Guelph
Co-Author(s)
Leacy A1, Akmeemana P1, Vendramelli R2, Alkie T3, Goens M1, Truong T2, Santos I1, Kobasa D2, Berhane Y3, Wootton S1, Susta L1. 1Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Canada 2Special Pathogens, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Canada 3National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Winnipeg, Canada
Abstract Category
Fighting & Responding
Abstract
Highly pathogenic avian influenza virus (HPAIV) H5N1 of Eurasian clade 2.3.4.4b is causing a worldwide outbreak in wild birds and poultry, with spillover into a range of mammals. Here, a recombinant Newcastle disease virus (NDV) expressing a clade-matched hemagglutinin (HA) with a deleted cleavage site (named NDV-H5-wt-del) was tested as a vaccine candidate in multiple species. Immunogenicity was tested in poultry (chickens and turkeys) and mammals (hamsters). Groups of 3-week-old chickens and turkeys (5-8/group) received escalating vaccine doses (105-6-7 focus forming units (FFU)) via the oculo-nasal route in a prime-boost regimen 21 days apart. Hamsters (5/group) received 107 FFU intranasally in a prime-boost regimen 28 days apart. In hamsters, the vaccine was highly immunogenic, with approximately a 20-fold anti-HA serum IgG increase compared to controls. In poultry, the vaccine induced increased antibody titres in a dose-dependent manner, with the highest dose inducing up to 1:256 hemagglutinin-inhibition titers in chickens. To evaluate efficacy, chickens and ferrets were vaccinated with 107 and 108 FFU of NDV-H5-wt-del via the oculo-nasal and intranasal routes in a prime-boost regimen, respectively, and then challenged with a lethal dose of clade-matched H5N1. Vaccinated animals of both species had 100% survival and no clinical signs, as opposed to 100% mortality seen in controls. Vaccinated and infected chickens also shed significantly less compared to controls, and did not transmit challenge virus to unvaccinated contact birds. These results show that mucosally-delivered NDV vectored vaccines are immunogenic and protective against HPAIV in multiple species.