Topical administration of HSV gD-IL-2 DNA is highly protective against murine herpetic stromal keratitis

To evaluate the immunopreventive effect of eyedrops that contain gD-IL-2 DNA (a chimeric gene of the glycoprotein D gene of herpes simplex virus type I (HSV-1) and human interleukin-2 (IL-2) on murine herpetic keratitis.

A plasmid containing gD-IL-2 (pHDLneo1) was constructed. The eyedrops containing 90 microg/10 microL of the DNA was instilled bilaterally into the conjunctival sacs of BALB/c mice on days 0 and 7. Three weeks after the last administration, neutralizing antibody, delayed-type hypersensitivity (DTH), and 51Cr-release from infected targeted cells by lymphocytes from the cervical lymph nodes and spleen were determined. Immunized mice were challenged with HSV-1, after which the clinical signs of the corneal epithelia and stroma were scored.

Specific neutralizing antibody was raised and prominent DTH reaction was elicited from immunized mice. Lymphocytes obtained from the local lymph nodes and spleen vigorously potentiated the cytotoxic activity against the virus-infected cells. Clinically, the development of stromal keratitis was completely inhibited, but prevention or reduction of HSV-1 epithelial lesions was not demonstrated statistically.

Topical immunization with a DNA vaccine encoding gD-IL-2 totally prevented the development of herpetic stromal keratitis. This procedure is a simple and convenient method for possible clinical application in the future.