CRISPR/Cas9 Reduces Viral Load in a BALB/c Mouse Model of Ocular Herpes Infection

Background/Objectives: Simplexvirus humanalpha1 (HSV-1) can cause herpetic keratitis, which is the most common cause of infectious blindness in developed countries. Some patients can develop toxicity or resistance to available treatments and may require keratoplasty. Methods: As an alternative therapy, the CRISPR/Cas9 anti-HSV-1 activity was assessed in an experimental model of BALB/c mice. Results: The results showed that the viral load in the eyes of mice inoculated with HSV-1 at 10⁷ PFU/mL was 4.5 ± 0.2 log₁₀ copies/mL. In contrast, mice inoculated with 10⁹ PFU/mL exhibited a high viral load of 8.1 ± 0.4 log₁₀ copies/mL. The detection of HSV-1 DNA and lesions in the eye was consistent with the viral inoculum of the infection. Next, antiviral activity showed that 200 ng/µL of CRISPR/Cas9 reduced the viral load by 2 logs (p ≤ 0.0001), as well as the lesion scores, compared to the untreated group. Conclusions: Together, the data suggest that CRISPR/Cas9 could be investigated as an alternative therapy for ocular herpes.