Researchers in Detroit-based Wayne State University’s department of ophthalmology, visual, and anatomical sciences have discovered in experimental models that the Zika virus can cause glaucoma. The study was published in mSphere, a peer-reviewed journal of the American Society of Microbiology.
Zika virus, or ZIKV poses challenges in reproductive health and has been shown to cause neurological disorders, primarily microcephaly, or the abnormal shrinking of the head circumference. Several clinical studies have also linked ZIKV to ocular deformities.
“The eye is protected from systemic infection due the presence of a protective barrier called the blood retinal barrier,” says Ashok Kumar, associate professor and lead author of the study. “Previous studies from our laboratory have shown that ZIKV has the ability to infect and replicate in cells making the blood retinal barrier, hence potentially allowing the entry of ZIKV into the eye.
“As the research interest of our laboratory is to study host-pathogen interactions, Dr. Singh made an unexpected observation that ZIKV-infected mice had an increased intraocular pressure, or IOP, in their eyes. Since elevated IOP is one of the hallmarks of glaucoma, the second most common blinding eye disease, we pursued this new line of investigation.”
Pawan Kumar Singh, a research scientist in Kumar’s lab, Dr. Anju Goyal, associate professor, and Dr. Mark Juzych, professor and chair, were also study team members.
“Glaucoma is classically viewed as a genetic and age-related disease and has rarely been associated with congenital infection among infants,” says Juzych. “One of the unique aspects of this study is the link between infectious agents as triggers of glaucoma. Because of the complexity of glaucoma pathobiology, our study may provide other avenues to study this disease.”
Recent clinical cases from ZIKV-affected countries have raised global alarm that there is a possible link between congenital glaucoma and ZIKV infection.
“In this study, we showed that ZIKV can readily infect human trabecular meshwork cells, a key cell type that regulates the flow of aqueous humor and maintains normal IOP in our eyes,” says Singh. “Moreover, ZIKV was able to replicate and produce infectious virions in these cells and caused inflammation. Most importantly, eyes of ZIKV-infected mice exhibited glaucomatous pathology characterized by death and loss of retinal ganglion cells and damage to the optic nerve, resulting in disruption of axonal transport.”
The scientists are now investigating the underlying mechanisms for ZIKV-induced glaucoma to identify potential targets for therapeutic intervention.
In another recent study published in the journal The Ocular Surface, Singh showed that ZIKV can infect human primary corneal epithelial cells.
“ZIKV has been shown to be present in the tears of human and experimental mouse models, leading us to conclude the potential risk of ZIKV transmission during corneal transplants, especially those residing in endemic zones of ZIKV infections,” says Kumar.
The study published in mSphere is available here.
