Identification and characterization of stable attachment receptors for herpes simplex virus.

Abstract

Herpes simplex virus (HSV) are important human pathogens that cause, or are associated with, infectious diseases in humans. HSV infects susceptible cells by at least two steps of attachment that lead to direct fusion of virus envelope with the plasma membrane at neutral pH. The objective of this dissertation was to identify and characterize the function in entry of HSV receptors that are not heparan sulfate (HS). Vital to this objective, we isolated and characterized poorly susceptible clonal porcine cells that have functional HS and are defective only in virus entry. We find that successful HSV entry requires a non-HS receptor on the cell surface and glycoprotein D on the virion. The clonal porcine cell system facilitates identification by genetic transfer of human genes that confer HSV susceptibility to cells defective in HSV entry. One such human gene was recently cloned and shown to mediate HSV entry into Chinese hamster ovary (CHO) cells. We show that this human gene, called Herpes Virus Entry Mediator, (HVEM), allows efficient entry of both HSV serotypes into porcine cells. HVEM interacts with the virus to allow stable binding to porcine cells. Furthermore, HVEM co-precipitates, and thus interacts in some manner, with glycoprotein H and probably glycoprotein D of HSV. Independently, using the porcine cell system we have isolated at least HVEM and find that several other genes in a human cDNA library are candidates to confer susceptibility for HSV Porcine cells provide an excellent in vitro system to identify and characterize human genes important for HSV entry. Identification of HVEM and other human receptor genes and determining their function will provide insights into the molecular and physical events that mediate viral entry, spread, pathogenesis and tropism. HSV is one of many viruses that infect cells through multiple attachments and interactions of the virus envelope with the cell membrane. Elucidation of HSV-cell interactions during entry will provide an understanding of basic mechanisms of membrane fusion.