Journal Article

Neutralizing Antibodies Induced by Recombinant Virus-Like Particles of Enterovirus 71 Genotype C4 Inhibit Infection at Pre- and Post-attachment Steps

Ku, Zhiqiang, Ye, Xiaohua, Liu, Qingwei, Li, Yan, Huang, Zhong, Cai, Yicun, Su, Zhiguo, Huang, Xulin

2013

Overview

Enterovirus 71 (EV71) is a major causative agent of hand, foot and mouth disease, which has been prevalent in Asia-Pacific regions, causing significant morbidity and mortality in young children. Antibodies elicited by experimental EV71 vaccines could neutralize infection in vitro and passively protect animal models from lethal challenge, indicating that neutralizing antibodies play an essential role in protection. However, how neutralizing antibodies inhibit infection in vitro remains unclear. In the present study, we explored the mechanisms of neutralization by antibodies against EV71 virus-like particles (VLPs). Recombinant VLPs of EV71 genotype C4 were produced in insect cells using baculovirus vectors. Immunization with the VLPs elicited a high-titer, EV71-specific antibody response in mice. Anti-VLP mouse sera potently neutralized EV71 infection in vitro. The neutralizing antibodies in the anti-VLP mouse sera were found to target mainly an extremely conserved epitope (FGEHKQEKDLEYGAC) located at the GH loop of the VP1 protein. The neutralizing anti-VLP antisera were able to inhibit virus binding to target cells efficiently. In addition, post-attachment treatment of virus-bound cells with the anti-VLP antisera also neutralized virus infection, although the antibody concentration required was higher than that of the pre-attachment treatment. Collectively, our findings represent a valuable addition to the understanding of mechanisms of EV71 neutralization and have strong implications for EV71 vaccine development.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Analysis / Animal models / Animals / Antibodies / Antibodies, Neutralizing - immunology / Antibodies, Viral - immunology / Antibody Formation / Antibody response / Antigenic determinants / Antisera / Attachment / Baculoviridae - immunology / Baculovirus / Biology / Cercopithecus aethiops - immunology / Children / E coli / Enterovirus / Enterovirus A, Human - immunology / Enterovirus Infections - immunology / Epitopes / Epitopes - immunology / Escherichia coli / Female / Genetic aspects / Genomes / Genotype / Genotype & phenotype / Growth hormone / Hand-foot-and-mouth disease / Health aspects / Immunization / Immunology / In vitro methods and tests / Infection / Infections / Insect cells / Insecta - immunology / Insects / Laboratories / Medical research / Medicine / Methods / Mice / Mice, Inbred BALB C / Morbidity / Neutralization / Neutralization Tests - methods / Neutralizing / Polyclonal antibodies / Process engineering / Proteins / Sf9 Cells / Vaccination - methods / Vaccine development / Vaccines / Vectors / Vero Cells / Viral Vaccines - immunology / Virion - immunology / Virology / Virus diseases / Virus-like particles / Viruses / VP1 protein / Wildlife conservation