Antigenic and Receptor Binding Properties of Enterovirus 68

Abstract

Increased detection of enterovirus 68 (EV68) among patients with acute respiratory infections has been reported from different parts of the world in the late 2000s since its first detection in pediatric patients with lower-respiratory-tract infections in 1962. However, the underlying molecular mechanisms for this trend are still unknown. We therefore aimed to study the antigenicity and receptor binding properties of EV68 detected in recent years in comparison to the prototype strain of EV68, the Fermon strain. We first performed neutralization (NT) and hemagglutination inhibition (HI) tests using antisera generated for EV68 strains detected in recent years. We found that the Fermon strain had lower HI and NT titers than recently detected EV68 strains. The HI and NT titers were also significantly different between strains of different genetic lineages among recently detected EV68 strains. We further studied receptor binding specificities of EV68 strains for sialyloligosaccharides using glycan array analysis. In glycan array analysis, all tested EV68 strains showed affinity for ␣2-6-linked sialic acids (␣2-6 SAs) compared to ␣2-3 SAs. Our study demonstrates that emergence of strains with different antigenicity is the possible reason for the increased detection of EV68 in recent years. Additionally, we found that EV68 preferably binds to ␣2-6 SAs, which suggests that EV68 might have affinity for the upper respiratory tract. IMPORTANCE Numbers of cases of enterovirus 68 (EV68) infection in different parts of the world increased significantly in the late 2000s.We studied the antigenicity and receptor binding properties of recently detected EV68 strains in comparison to the prototype strain of EV68, Fermon. The hemagglutination inhibition (HI) and neutralization (NT) titers were significantly different between strains of different genetic lineages among recently detected EV68 strains. We further studied receptor binding specificities of EV68 strains for sialyloligosaccharides using glycan array analysis, which showed affinity for ␣2-6-linked sialic acids (␣2-6 SAs) compared to ␣2-3 SAs. Our study suggested that the emergence of strains with different antigenicities was the possible reason for the increased detections of EV68 in recent years. Additionally, we revealed that EV68 preferably binds to ␣2-6 SAs. This is the first report describing the properties of EV68 receptor binding to the specific types of sialic acids.

Enterovirus D68 receptor requirements unveiled by haploid genetics

“…In EV-D68, the canyon is unusually shallow and narrow, possibly excluding use of large protein receptors (12). Both sensitivity of EV-D68 infection to neuraminidase (NA) treatment and hemagglutination assays point to the use of Sia as the receptor (13,14). However, beside the role of a terminal Sia residue on the receptor, little is known about the type(s) of Sia that can be used by Significance Enterovirus D68 (EV-D68) is an emerging pathogen that recently caused a large outbreak of severe respiratory disease in the United States and is associated with cases of paralysis.…”

Trisaccharide containing α2,3-linked sialic acid is a receptor for mumps virus

“…3A) using a glycoconjugate-spotted microplate (19,20). The glycoconjugates represent major sialylated glycans found in the human respiratory tract (21), and their structural compositions are described in Fig.…”

Human picornaviruses associated with neurological diseases and their neutralization by antibodies

“…Immunized guinea pigs generated high titres of neutralizing antibodies for the original virus and viruses of the same lineage, but very little crossneutralization between genetic lineages was found [166]. Importantly, the majority of sequence variation between EV-D68 lineages is localized to the VP1 BC and DE surface loops [55,85,166], which are the most variable and are probably epitope-containing in enteroviruses. Indeed, VP1 likely contains antigenic determinants as the increase in its gene diversity correlates with an increase in the number of EV-D68 detections [167], reflecting the appearance of antigenically new viruses in the population.…”

“…Substitution dynamics within the viral genome also suggests the localization of antigenic epitopes to VP1: several positions in VP1 BC and DE loops (Fig. 3b) are undergoing positive selection and might be associated with antigenic differences between EV-D68 genetic lineages [166]. Nevertheless, to date the exact immunogenic epitopes of EV-D68 are only predictive and have not been mapped.…”

“…Imamura et al studied the immunogenic properties of 12 EV-D68 types belonging to all three lineages of EV-D68 -A, B and C [85]. Immunized guinea pigs generated high titres of neutralizing antibodies for the original virus and viruses of the same lineage, but very little crossneutralization between genetic lineages was found [166]. Importantly, the majority of sequence variation between EV-D68 lineages is localized to the VP1 BC and DE surface loops [55,85,166], which are the most variable and are probably epitope-containing in enteroviruses.…”