Abstract
Abstract: :
Purpose: (i) To assess the role of herpes simplex virus type-1 (HSV-1) envelope glycoproteins in viral entry. (ii) Delineate the molecular mechanism of the HSV-1 entry process in order to find new ways to prevent infection of ocular tissues and infectious blindness. Methods: Chinese hamster ovary (CHO) cells were co-transfected with plasmids expressing HSV-1 entry receptor (HVEM, Nectin-1 or 3-OS-HS) and one or more of the envelope glycoproteins, gB, gD, gH and gL. Cells co-expressing receptors and glycoproteins were infected with a recombinant ß-galactosidase-expressing HSV-1 and were subsequently examined for glycoprotein-mediated entry interference (resistance) phenomenona. Cell- Enzyme Linked Immunosorbent Assay (ELISA) and Flow Cytometry analyses were used to assess surface expression of viral glycoproteins. Results: As a novel finding, cellular expression of HSV-1 glycoproteins, gH-gL (expressed as hetero-dimer), were found to render cells resistant to HSV-1 entry, similar to previously described gD-mediated interference. When expressed together with gD, the gH-gL-mediated interference was even more pronounced; suggesting an additive effect of gD expression. In contrast, the cellular expression of gB in presence or absence of other glycoproteins did not have any significant effect on HSV-1 entry. From Cell ELISA and Flow cytometry data, the gH-gL-mediated interference appears to be a cell-surface associated phenomenon. Conclusions: Our study identifies a new set of HSV-1 glycoproteins that, when expressed in susceptible cells, confer resistance to viral entry. Previously this phenomenon was limited to gD. Since both gD-mediated interference and gH-gL-mediated interference appear very similar, it is suggestive that like gD, endogenous gH-gL might also confer resistance by interacting with and sequestering a cellular receptor/partner from exogenous virus. This is the first indication of its kind that HSV-1 gH-gL specific entry receptors might indeed exist.
Keywords: herpes simplex virus • molecular biology