Viral Retinopathy in Experimental Models of Zika Infection

PURPOSE. Emerging evidence has shown that both congenital and adult Zika virus (ZIKV) infection can cause eye diseases. The goals of the current study were to explore mechanisms and pathophysiology of ZIKV-induced eye defects. METHODS. Wild-type or A129 interferon type I receptor-deficient mice were infected by either FSS13025 or Mex1-7 strain of ZIKV. Retinal histopathology was measured at different time points after infection. The presence of viral RNA and protein in the retina was determined by in situ hybridization and immunofluorescence staining, respectively. Growth curves of ZIKV in permissive retinal cells were assessed in cultured retinal pigment epithelial (RPE) and Muller glial cells. RESULTS. ZIKV-infected mice developed a spectrum of ocular pathologies that affected multiple layers of the retina. A primary target of ZIKV in the eye was Muller glial cells, which displayed decreased neurotrophic function and increased expression of proinflammatory cytokines after infection. ZIKV also infected RPE; and both the RPE and Muller cells expressed viral entry receptors TYRO3 and AXL. Retinitis, focal retinal degeneration, and ganglion cell loss were observed after the clearance of viral particles. CONCLUSIONS. Our data suggest that ZIKV can infect infant eyes with immature blood-retinal barrier and cause structural damages to the retina. The ocular findings in microcephalic infants may not be solely caused by ZIKV-induced impairment of neurodevelopment.