Safety and immunogenicity of a delta inulin-adjuvanted inactivated Japanese encephalitis virus vaccine in pregnant mares and foals
Date
2014
Authors
Bielefeldt Ohmann, H.
Prow, N.A.
Wang, W.
Tan, C.S.E.
Coyle, M.
Douma, A.
Hobson Peters, J.
Kidd, L.
Hall, R.A.
Petrovsky, N.
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Journal article
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Veterinary research (VR), 2014; 45(1):1-9
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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 (WNV<inf>KUN</inf>). 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 WNV<inf>KUN</inf>. 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 WNV<inf>KUN</inf> 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 WNV<inf>KUN</inf>.
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Copyright 2014 The Authors. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (), which permits unrestricted use,distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver applies to the data made available in this article, unless otherwise stated. (http://creativecommons.org/licenses/by/4.0)