Safety and immunogenicity of a delta inulin-adjuvanted inactivated Japanese encephalitis virus vaccine in pregnant mares and foals

Vet Res. 2014 Dec 17;45(1):130. doi: 10.1186/s13567-014-0130-7.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / administration & dosage
  • Adjuvants, Immunologic / adverse effects
  • Adjuvants, Immunologic / pharmacology*
  • Animals
  • Antibodies, Viral / immunology*
  • Cross Reactions
  • Encephalitis Virus, Japanese / immunology*
  • Encephalitis, Japanese / prevention & control
  • Encephalitis, Japanese / veterinary*
  • Encephalitis, Japanese / virology
  • Female
  • Horse Diseases / prevention & control*
  • Horse Diseases / virology
  • Horses
  • Inulin / administration & dosage
  • Inulin / adverse effects
  • Inulin / physiology*
  • Pregnancy
  • Viral Vaccines / administration & dosage
  • Viral Vaccines / adverse effects
  • Viral Vaccines / immunology*


  • Adjuvants, Immunologic
  • Antibodies, Viral
  • Viral Vaccines
  • Inulin