Role of 3–O–Sulfated Heparan Sulfate in Herpes Simplex Virus Type–1 Entry and Spread

Abstract

Abstract: : Purpose: The purpose of this study was to determine the effects of various 3–O–sulfated forms of heparan sulfate (HS) on herpes simplex virus (HSV–1 and HSV–2) entry and spread. Methods: Recombinant ß–galactosidase–expressing HSV–1 and HSV–2 virions were used for assaying viral entry. A virus–free cell fusion assay was used for comparing the cell–to–cell fusion efficiency of various 3–O–sulfated HS. An enzyme–linked immunosorbent assay (ELISA) was developed to detect HS expression on cell surface. Results: Chinese hamster ovary–K1 (CHO–K1) cells expressing 3–O–sulfotransferase–3A (3–OST–3A) or 3–OST–5 were susceptible to HSV–1, but not HSV–2, entry, while 3–OST–1 expression did not facilitate entry of either HSV–1 or HSV–2. Similarly, 3–OST–3A or 3–OST–5, but not 3–OST–1, expression in CHO–K1 cells supported cell–to–cell fusion when mixed and co–cultivated with cells expressing HSV–1 glycoproteins. The cell fusion mediated by 3–OST–3A or –5 exhibited similar requirements but was independent of protein receptors, HVEM or Nectin–1. Additionally, co–expression of 3–OST–3A and 3–OST–5 significantly enhanced HSV–1 entry and cell–to–cell fusion without any detectable increase in total cell surface HS. Conclusions:Our findings indicate that entry and fusion receptors generated by 3–O–sulfation of HS are specific for HSV–1. It was also found that not all 3–O–sulfations of HS result in receptors for HSV–1 entry and cell fusion; and receptors generated by 3–OST–3A and 3–OST–5 are likely to differ in structure.

Keywords: herpes simplex virus • glycoconjugates/glycoproteins • keratitis