title: Safety and immunogenicity of a delta inulin-adjuvanted inactivated Japanese encephalitis virus vaccine in pregnant mares and foals.
abstract: In 2011, following severe flooding in Eastern Australia, an unprecedented epidemic of equine encephalitis occurred in South-Eastern Australia, caused by Murray Valley encephalitis virus (MVEV) and a new variant strain of Kunjin virus, a subtype of West Nile virus (WNVKUN). This prompted us to assess whether a delta inulin-adjuvanted, inactivated cell culture-derived Japanese encephalitis virus (JEV) vaccine (JE-ADVAX™) could be used in horses, including pregnant mares and foals, to not only induce immunity to JEV, but also elicit cross-protective antibodies against MVEV and WNVKUN. Foals, 74-152 days old, received two injections of JE-ADVAX™. The vaccine was safe and well-tolerated and induced a strong JEV-neutralizing antibody response in all foals. MVEV and WNVKUN antibody cross-reactivity was seen in 33% and 42% of the immunized foals, respectively. JE-ADVAX™ was also safe and well-tolerated in pregnant mares and induced high JEV-neutralizing titers. The neutralizing activity was passively transferred to their foals via colostrum. Foals that acquired passive immunity to JEV via maternal antibodies then were immunized with JE-ADVAX™ at 36-83 days of age, showed evidence of maternal antibody interference with low peak antibody titers post-immunization when compared to immunized foals of JEV-naïve dams. Nevertheless, when given a single JE-ADVAX™ booster immunization as yearlings, these animals developed a rapid and robust JEV-neutralizing antibody response, indicating that they were successfully primed to JEV when immunized as foals, despite the presence of maternal antibodies. Overall, JE-ADVAX™ appears safe and well-tolerated in pregnant mares and young foals and induces protective levels of JEV neutralizing antibodies with partial cross-neutralization of MVEV and WNVKUN.
authors.affiliation: School of Veterinary Science, University of Queensland, Gatton Campus, Gatton 4343, Qld, Australia. h.bielefeldtohmann1@uq.edu.au.
authors.forename: Helle
authors.initials: H
authors.lastname: Bielefeldt-Ohmann
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Prow
authors.forename: Wenqi
authors.initials: W
authors.lastname: Wang
authors.forename: Cindy S E
authors.initials: CS
authors.lastname: Tan
authors.forename: Mitchell
authors.initials: M
authors.lastname: Coyle
authors.forename: Alysha
authors.initials: A
authors.lastname: Douma
authors.forename: Jody
authors.initials: J
authors.lastname: Hobson-Peters
authors.forename: Lisa
authors.initials: L
authors.lastname: Kidd
authors.forename: Roy A
authors.initials: RA
authors.lastname: Hall
authors.forename: Nikolai
authors.initials: N
authors.lastname: Petrovsky
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology*; D003429:Cross Reactions; D004664:Encephalitis Virus, Japanese / Q000276:immunology*; D004672:Encephalitis, Japanese / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D005260:Female; D006734:Horse Diseases / Q000517:prevention & control* / Q000821:virology; D006736:Horses; D007444:Inulin / Q000008:administration & dosage / Q000009:adverse effects / Q000502:physiology*; D011247:Pregnancy; D014765:Viral Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D014765:Viral Vaccines; D007444:Inulin