This FDA-approved drug shows promise for treating herpes viruses

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In a new study, researchers found that a drug currently prescribed to treat a rare enzyme deficiency can help cells clear the herpes viruses.

They found that the antiviral activity of the drug—called phenylbutyrate, or PBA—was even better when used along with acyclovir, a common herpes treatment.

When used in combination, less acyclovir is needed to effectively suppress the virus compared to acyclovir alone.

This is important because acyclovir is also known to have toxic side effects in the kidneys.

The research was conducted by a team at the University of Illinois at Chicago.

There are two types of herpes simplex virus: herpes simplex 1, which infects the eyes and mouth and is a leading cause of blindness, and herpes simplex 2, a genital infection that may cause painful sores and can seriously impair quality of life.

Treatment for both infections often includes acyclovir—a systemic medication taken orally. However, long-term use often results in resistance to the drug as well as kidney damage.

There are very few drugs available to treat herpes simplex viruses, so when new drugs become available, especially drugs that enable fewer side effects, it is a welcome discovery.

Drug acyclovir can have very toxic effects on the kidneys, especially when it is given in higher doses for HSV-induced encephalitis, which is rare but can be deadly.

By combining acyclovir with PBA, doctors need less acyclovir to effectively treat HSV-1 herpes virus.

In the study, the team tested the antiviral effects of PBA and found that in cells the drug disrupts the ability of the virus to hijack the cellular machinery used to produce proteins.

Normally, viruses infect cells and force them to produce viral proteins so the virus can replicate itself.

But the cell also continues to produce proteins for its own use, leading to a lot of stress in the structure—called the endoplasmic reticulum, or ER for short—that makes protein.

They found that PBA reduces stress on the ER, which allows the cell to focus on clearing the virus on its own.

The researchers found that in cells, PBA alone was able to clear HSV-1 from cells of donated human corneas or from donated human skin tissue just as well as acyclovir.

In a mouse model of ocular HSV-1 infection, PBA was able to clear the virus from the eyes.

In an animal model of HSV-2 vaginal infection, mice that received PBA had no signs of the HSV-2 virus in tissues, similar to mice treated with acyclovir.

When the team tested a combination of PBA with acyclovir cells infected with HSV-1, the drug combo was able to completely clear the virus from the cells faster and better than either drug alone.

The team says PBA is an exciting new therapy for treating herpes infections that can help reduce side effects linked to long term or high dose use of acyclovir, a commonly prescribed medication to treat herpes viruses.

The added bonus of this drug already being approved by the FDA to treat a rare enzyme disorder means that doctors may be able to quickly develop a marketable new combination therapy in the near future.

One author of the study is Dr. Deepak Shukla.

The study is published in the journal of Science Advances.

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