Structural features of nectin-2 (HveB) required for herpes simplex virus entry

Area of Science:

• Virology
• Cell Biology
• Immunology

Background:

• Herpes simplex virus (HSV) entry into host cells involves the binding of viral glycoprotein D (gD) to cellular receptors.
• Human nectin-2, an immunoglobulin superfamily member, acts as a gD receptor for HSV-2, certain HSV-1 variants, and pseudorabies virus (PRV).
• The gD binding site on nectin-2 is localized to its N-terminal variable-like (V) Ig domain.

Purpose of the Study:

• To identify specific amino acid sequences within human nectin-2 that are critical for mediating HSV entry.
• To understand the functional role of different regions of the nectin-2 V domain in viral receptor activity.

Main Methods:

• Construction of chimeric nectin-2 molecules by exchanging sequences between human and mouse nectin-2.
• Expression of these chimeric molecules in Chinese hamster ovary (CHO) cells, which lack endogenous gD receptors.
• Assay of chimeric molecule expression on the cell surface and their ability to mediate viral entry.

Main Results:

• Chimeric molecules containing the human nectin-2 V domain demonstrated HSV entry activity.
• Specific amino acid substitutions (residues 75-81 or 89) in the mouse nectin-2 V domain conferred HSV-1/Rid entry activity.
• These modified mouse nectin-2 molecules also showed enhanced HSV-2 entry and gained the ability to mediate wild-type HSV-1 entry.
• Mutation of human nectin-2 residue 89 to its mouse counterpart (M89F) abolished HSV entry activity.

Conclusions:

• Two distinct amino acid sequences within the nectin-2 V domain, adjacent to the C' and C" beta-strands, are critical for HSV entry.
• These identified regions are functionally analogous to known viral binding sites on other Ig superfamily members like CD4 and CD155.
• The study elucidates key molecular determinants for nectin-2 mediated HSV cell entry.