Cross-reactive neutralizing antibody epitopes against Enterovirus 71 identified by an in silico approach

Abstract

Currently, infections of hand, foot and mouth disease (HFMD) due to Human Enterovirus 71 (EV71) cannot be prevented or treated, as there are no suitable vaccines or antiviral drugs. This study aimed to identify potential vaccine candidates for EV71 using in silico analysis of its viral capsid proteins. A combined in silico approach utilizing computational hidden Markov model (HMM), propensity scale algorithm, and artificial learning, identified three 15-mer structurally conserved B-cell epitope candidates lying within the EV71 capsid proteins. Peptide vaccine candidates incorporating a target B-cell epitope and a promiscuous T-cell epitope from the related polio virus were synthesized using solid-phase Fmoc chemistry. Inbred BALB/C mice which were inoculated with two 10μg doses of the synthetic peptide, generated anti-peptide antibodies. Purified IgG isolated from pooled sera of the inoculated mice neutralized EV71 infections in vitro. Furthermore, these neutralizing antibodies were cross-reactive against other members of the Picornaviridae family, demonstrating greater than 50% virus neutralization. This indicates that the current approach is promising for the development of synthetic peptide-based vaccine candidates against Picornaviridae. Development of effective vaccines is of paramount importance in managing the disease in the Asia Pacific regions where this virus is endemic and has significant social, economic and public health ramifications.

Chimeric Virus-Like Particle Vaccines Displaying Conserved Enterovirus 71 Epitopes Elicit Protective Neutralizing Antibodies in Mice through Divergent Mechanisms

“…For example, Ku et al reported that a geometric mean neutralizing titer of 9,190 was induced in mouse sera after three immunizations with EV71 VLP (equivalent to 5 g of VP0) plus alum adjuvant (18). This is as expected because, presumably, an EV71 VLP possesses all of the identified and unidentified linear neutralizing epitopes (10,29,30) and unidentified conformational neutralizing epitopes that are present on an authentic EV71 virion. In contrast, in the present study, each HBcSP55 or HBcSP70 fusion contains only one EV71 epitope.…”

Genetic characteristics of coxsackievirus A16 associated with hand, foot, and mouth disease in Nanjing, China

“…It has been determined that the neutralization epitopes of EV are mainly located on capsid proteins, especially protein VP1 [23,29]. Several neutralizing epitopes on the VP1 structural protein of EV71 have been reported [30,31], but those capable of eliciting CVA16-neutralizing antibodies remained to be elucidated for a long time. Recently, a report indicated the identification of six neutralizing linear epitopes of CVA16 on the VP1 protein [23].…”

Crystal Structures of Yeast-Produced Enterovirus 71 and Enterovirus 71/Coxsackievirus A16 Chimeric Virus-Like Particles Provide the Structural Basis for Novel Vaccine Design against Hand-Foot-and-Mouth Disease

“…The neutralizing epitopes of EV71 have been screened extensively, including the identification of synthetic peptides that induce neutralizing antibodies and the mapping of antibody neutralization escape mutations. Some major neutralizing epitopes of EV71 have been mapped to residues 97 to 105, 163 to 177, 208 to 222 (SP70 epitope), and 253 to 267 of VP1 (2)(3)(4); residues 141 to 150 of VP2 (5); and residues 1 to 15 and 28 to 42 of VP3 (4). Lee et al identified a strain-specific neutralization epitope of EV71 in a cryo-electron microscopy (cryo-EM) study of EV71 in complex with Fab from a neutralizing antibody (6).…”