Journal of Vaccines & Vaccination

Advax-adjuvanted killed Japanese encephalitis virus (JEV) vaccine is safe in pregnant mares and in foals and induces robust immunological memory

5^th Asia Pacific Global Summit and Expo on Vaccines & Vaccination

July 27-29, 2015 Brisbane, Australia

Helle Bielefeldt-Ohmann1,2, Natalie A. Prow2,3, Wenqi Wang1, Cindy S.E. Tan2,3, Mitchell Coyle4, Alysha Douma4, Jody Hobson-Peters2,3, Lisa Kidd1, Roy A. Hall2,3 and Nikolai Petrovsky5,6

Scientific Tracks Abstracts: J Vaccines Vaccin

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-ADVAXTM) 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-ADVAXTM. 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-ADVAXTM 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-ADVAXTM 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-na�ve dams. Nevertheless, when given a single JE-ADVAXTM 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-ADVAXTM 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.