Equine major histocompatibility complex class I molecules act as entry receptors that bind to equine herpesvirus-1 glycoprotein D

Michihito Sasaki,Takashi Kimura,Minoru Okamoto,Kazuya Matsuda,Hirofumi Sawa,Hideto Fukushi,Tadaki Suzuki,Rie Hasebe,Yoshinori Makino,Hiroyuki Taniyama

doi:10.1111/j.1365-2443.2011.01491.x

Abstract

The endotheliotropism of equine herpesvirus-1 (EHV-1) leads to encephalomyelitis secondary to vasculitis and thrombosis in the infected horse central nervous system (CNS). To identify the host factors involved in EHV-1 infection of CNS endothelial cells, we performed functional cloning using an equine brain microvascular endothelial cell cDNA library. Exogenous expression of equine major histocompatibility complex (MHC) class I heavy chain genes conferred susceptibility to EHV-1 infection in mouse NIH3T3 cells, which are not naturally susceptible to EHV-1 infection. Equine MHC class I molecules bound to EHV-1 glycoprotein D (gD), and both anti-gD antibodies and a soluble form of gD blocked viral entry into NIH3T3 cells stably expressing the equine MHC class I heavy chain gene (3T3-A68 cells). Treatment with an anti-equine MHC class I monoclonal antibody blocked EHV-1 entry into 3T3-A68 cells, equine dermis (E. Derm) cells and equine brain microvascular endothelial cells. In addition, inhibition of cell surface expression of MHC class I molecules in E. Derm cells drastically reduced their susceptibility to EHV-1 infection. These results suggest that equine MHC class I is a functional gD receptor that plays a pivotal role in EHV-1 entry into equine cells.

Highlights

Equine herpesvirus-1 (EHV-1), an alphaherpesvirus of the family Herpesviridae with a worldwide distribution, can cause respiratory disease, abortion and encephalo-myelitis in horses
We first examined the attachment of EHV-1 to equine brain microvascular endothelial cells (EBMECs), which are highly susceptible to EHV-1 infection, and to murine fibroblast-derived NIH3T3 cells, which are considered resistant to EHV-1 infection
PT85A and H58A prevented EHV-1 entry into EBMECs (Fig. 2C). These results suggest that equine major histocompatibility complex (MHC) class I molecules are involved in EHV-1 entry into both 3T3-A68 cells and EBMECs

Summary

Introduction

Equine herpesvirus-1 (EHV-1), an alphaherpesvirus of the family Herpesviridae with a worldwide distribution, can cause respiratory disease, abortion and encephalo-. We identified an equine major histocompatibility complex (MHC) class I heavy chain gene that rendered NIH3T3 cells susceptible to EHV-1 infection, from a cDNA library of primary cultured EBMECs. Equine MHC class I directly interacted with EHV-1 gD, a viral protein known to be important for EHV-1 entry. EHV-1 dependence on MHC class I for entry was observed in equine cell types, but not in CHOK1, which is a nonequine cell line susceptible to EHV-1 infection. These results suggest that equine MHC class I acts as a gD receptor for EHV-1 entry into equine cell types, including CNS endothelial cells

Results

Discussion

Experimental procedures