Abstract
Purpose:
Herpes simplex virus-1 (HSV-1) infection of the cornea is the leading cause of infectious blindness in the developed world. Recent studies in cell culture and mouse models have suggested that a peptide blocking 3-O-sulfated heparan sulfate (3-OS-HS) can effectively inhibit HSV-1 infection of the corneal epithelium. This study aimed to assess the potential of an ex vivo organotypically-cultured corneal model to detect an inhibitory role of these peptides against HSV-1 infection.
Methods:
Corneal tissues were obtained from donated pig eyes and organotypically cultured. Tissues were either pretreated with G2 peptide (MPRRRRIRRRQK), control peptide (RVCGSIGKEVLG), or no peptide for 1 hour. The cornea were then scarified and infected topically with HSV-1 KOS at 10^6 PFU for 6, 12, and 36 hour time points. Tissues without both peptide and virus treatment and tissues exposed to only scarification were used as controls. Tissues were snap frozen in liquid nitrogen and stored for immunohistochemical analysis using polyclonal antibodies against HSV-1 antigens. The distribution and intensity of the immunostaining in the corneal epithelium, as well as the epithelial integrity, was assessed using light microscopy. Western blot analysis of homogenized corneal tissue was used to verify differences in viral protein levels.
Results:
Immunohistochemical results indicate increased presence of HSV-1 antigens in the epithelium of virally infected cultured corneas following control peptide or no peptide treatment at 6, 12 , and 36 hours postinfection compared to that detected in control, scarified, and G2-pretreated corneas. A relatively increased damage to the corneal epithelium was observed in corneas pretreated with control peptide or no peptide and subsequently virally infected compared to that observed in control, scarified, and G2-pretreated corneas.
Conclusions:
An ex vivo model using cultured corneas can be used for HSV-1 infection and therapeutic efficacy determination studies. HSV-1 infection of porcine corneal tissues appears to be inhibited with topical pretreatment with G2 peptide. This suggests an ability of these peptides to inhibit HSV-1 entry when applied as prophylaxis. Further studies are needed to fully evaluate the potential of G2 peptide as a therapeutic option against HSV-1.
Keywords: 545 herpes simplex virus •
482 cornea: epithelium •
661 proteoglycans/glycosaminoglycans