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Australian eye research reveals common virus threat

06/06/2018By Matthew Woodley • Staff Journalist
Common viruses may target the eye more frequently than previously thought, a Lion’s Eye Institute (LEI) study has found.

According to the LEI researchers, healthy eyes have been considered largely inaccessible to viruses, as well as “immune privileged”, meaning that exposure to a foreign antigen, such as a virus, should not trigger an inflammatory response. However, trials investigating the effect of cytomegalovirus on mice have shown this may not be the case.


“Our findings identify the eye as an unexpected reservoir for cytomegalovirus and suggest that common viruses may target the eye more frequently than appreciated.”
Valentina Voigt, LEI

More than half of all Australian adults carry the virus, but clinical symptoms are usually seen only in patients with compromised immune systems. Once a person is infected, the virus enters a dormant state in organs such as the lung, but it was believed that in people with healthy immune systems, tissues like the eyes would be inaccessible to the virus.

While outbreaks of viral diseases like Ebola and Zika raised the possibility that viruses could cause enduring infections in the eye, this was thought to be a feature of exotic viral infections. However, the researchers discovered that infecting mice with cytomegalovirus resulted in broad ocular infection, chronic inflammation and establishment of a dormant pool of virus in the eye – including in those with healthy immune systems.

As such, lead researcher Dr Valentina Voigt said the findings challenge the belief that immune privileged tissues such as the eye were only accessible to cytomegalovirus when the infected person’s immune system was severely compromised.

“Until now, it was thought that cytomegalovirus could not access the eye and certainly was unlikely to reside there indefinitely in a healthy host,” Voigt said.

“Our findings identify the eye as an unexpected reservoir for cytomegalovirus and suggest that common viruses may target the eye more frequently than appreciated. They also highlight that cytomegalovirus infection triggers sustained inflammatory responses in the eye, including the neural retina.”

LEI director of research and head of the Experimental Immunology Group, Professor Mariapia Degli-Esposti, said the research on mice was a reliable model for human cytomegalovirus infection.

“Since the mouse model of cytomegalovirus infection faithfully recapitulates most of the pathologies seen in people after infection with human cytomegalovirus, this study represents an important advance in understanding the full impact of this infection, especially in healthy subjects,” Degli-Esposti said.

More research is needed to determine whether the findings extend to humans, however the study’s authors said they suggest researchers and doctors may need to rethink the effects of cytomegalovirus – and, potentially, other viruses – on the eyes. In particular, some eye problems caused by dormant or reactivated cytomegalovirus in people with healthy immune systems may be misdiagnosed, leading to improper treatment that could damage vision. 

More reading: The full study.



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