Virology: How Does Herpes Simplex Virus Cause Inflammation Of The Brain?

The most common symptom of infection is a cold sore, but in some individuals the virus can also cause life-threatening inflammation of the brain (encephalitis); 70% of individuals who do not get treatment for this condition die.

New insight into the cellular proteins that the virus exploits to replicate itself and cause death from encephalitis has now been provided by a team of researchers at the National Cheng Kung University and the National Chiayi University, in the Republic of China, who analyzed human cell lines and mice infected with HSV-1.

In the study, expression of a cellular protein known as Egr1 was found to be increased after a human nerve cell line was infected with HSV-1. Further, Egr1 was shown to increase replication of the virus. Increased expression of Egr1 was also observed in the brain of mice infected with HSV-1.

Importantly, two different approaches to decrease Egr1 expression in the brain reduced the number of mice that died as a result of HSV-1 encephalitis, and this was associated with decreased numbers of viruses in the mice.

The authors therefore suggest that these data provide rationale for further studies to test whether blocking Egr1 could be a new strategy for preventing HSV-1–induced encephalitis and other conditions.