Interferon-gamma, macrophages, and virus spread after HSV-1 injection

Area of Science:

• Ophthalmology
• Virology
• Immunology

Background:

• Herpes simplex virus type 1 (HSV-1) infection in the anterior chamber (AC) of the eye causes inflammation but typically does not spread to the posterior segment.
• The mechanisms preventing HSV-1 spread from the anterior to the posterior of the eye are not fully understood.

Purpose of the Study:

• To investigate the role of interferon-gamma (IFN-γ) and Mac-1(+) cells in preventing the direct anterior-to-posterior spread of HSV-1 within the injected eye.
• To determine if these factors influence the location or timing of viral spread.

Main Methods:

• BALB/c mice received uniocular AC injections of HSV-1.
• Interferon (IFN)-α, IFN-β, and IFN-γ localization and mRNA expression were analyzed using immunofluorescence and qPCR.
• HSV-1 spread was examined in IFN-γ knockout mice and macrophage-depleted mice.

Main Results:

• IFN-α, IFN-β, and IFN-γ were detected in the anterior segment of infected eyes up to 72 hours post-infection.
• Increased mRNA levels of IFN-β and IFN-γ were observed 48-120 hours after infection.
• Absence of IFN-γ or macrophages did not alter the sites or timing of HSV-1 spread in the injected eye.

Conclusions:

• Protection of the retina from HSV-1 in the injected eye does not rely on IFN-γ or Mac-1(+) macrophages alone.
• The innate immune response to viral infections in the eye exhibits redundancy, involving multiple protective mechanisms.