A sialic acid binding site in a human picornavirus.

Georg Zocher,Thilo Stehle,Nitesh Mistry,Irmgard Hähnlein-Schick,Niklas Arnberg,Martin Frank,Jens-Ola Ekström,Félix A Rey

doi:10.1371/journal.ppat.1004401

Georg Zocher, Thilo Stehle + Show 6 more

Open Access

https://doi.org/10.1371/journal.ppat.1004401

Copy DOI

Abstract

The picornaviruses coxsackievirus A24 variant (CVA24v) and enterovirus 70 (EV70) cause continued outbreaks and pandemics of acute hemorrhagic conjunctivitis (AHC), a highly contagious eye disease against which neither vaccines nor antiviral drugs are currently available. Moreover, these viruses can cause symptoms in the cornea, upper respiratory tract, and neurological impairments such as acute flaccid paralysis. EV70 and CVA24v are both known to use 5-N-acetylneuraminic acid (Neu5Ac) for cell attachment, thus providing a putative link between the glycan receptor specificity and cell tropism and disease. We report the structures of an intact human picornavirus in complex with a range of glycans terminating in Neu5Ac. We determined the structure of the CVA24v to 1.40 Å resolution, screened different glycans bearing Neu5Ac for CVA24v binding, and structurally characterized interactions with candidate glycan receptors. Biochemical studies verified the relevance of the binding site and demonstrated a preference of CVA24v for α2,6-linked glycans. This preference can be rationalized by molecular dynamics simulations that show that α2,6-linked glycans can establish more contacts with the viral capsid. Our results form an excellent platform for the design of antiviral compounds to prevent AHC.

Highlights

Coxsackievirus A24 variant and enterovirus 70, members of the Picornaviridae family, cause acute hemorrhagic conjunctivitis, a highly contagious eye infection [1,2]
Cell binding and infection studies showed that enterovirus 70 (EV70) binds Neu5Ac in the context of an a2,3 linkage [18], while coxsackievirus A24 variant (CVA24v) is able to use both a2,3- and a2,6-linked Neu5Ac as receptors, with some preference for the a2,6-linkage
Crystal structure of the CVA24v particle To establish a structural basis for the recognition of sialic acid by CVA24v, we first determined the structure of intact CVA24v, an isolate of the Malaysia outbreak occurring during the 2002– 2004 acute hemorrhagic conjunctivitis (AHC) pandemic [5], at 1.40 Aresolution (Table 1, Figure S1)

Summary

Introduction

Coxsackievirus A24 variant and enterovirus 70, members of the Picornaviridae family, cause acute hemorrhagic conjunctivitis, a highly contagious eye infection [1,2]. The AHC-causing human picornaviruses CVA24v and EV70 use glycan-containing receptors for cell attachment [1,18]. Both viruses engage glycans that terminate in the sialic acid 5-N-acetyl-neuraminic acid (Neu5Ac). Cell binding and infection studies showed that EV70 binds Neu5Ac in the context of an a2,3 linkage [18], while CVA24v is able to use both a2,3- and a2,6-linked Neu5Ac as receptors, with some preference for the a2,6-linkage. The sialic acid-containing receptor is used by CVA24v on corneal but not conjunctival cells [19]. The molecular determinants underlying these interactions have been unknown for either virus

Methods

Results

Discussion

Conclusion