Immunoprotection of Inactivated EV71 Vaccine Against Enterovirus in Neonatal Rhesus Monkey

Abstract

Present study was conducted to evaluate the immunogenicity of one formalin-inactivated EV71 vaccine in neonatal rhesus monkeys ( Macaca mulatta ). Groups of four monkeys were immunized with either EV71 vaccine or mock by intra-muscular (IM, using needle) routes. Following primary immunization with 160EU vaccine given IM, the monkeys were boosted after 1 month with 160EU vaccine given IM. After the booster, most of the monkeys sero-converted and developed EV71 neutralizing antibodies. Importantly however, following a sham challenge with the live virus strain FY23 given 4 weeks after immunization, the neutralizing antibody titers rose rapidly indicating a vigorous anamnestic response. Based on the neutralizing antibody response following the vaccination and the extent of anamnestic response generated in the immunized monkeys, vaccination group was superior to mock group. This study indicates that the EV71 candidate vaccine is capable of generating protective levels of EV71 neutralizing antibodies in neunatal rhesus monkeys and primes the immune system effectively against a subsequent exposure to EV71.