A drug commonly used to treat heart failure and hypertension could also be an effective treatment against herpes. Spironolactone appears to block infections by the Epstein Barr virus (EBV), a type of herpes virus that can lead to mononucleosis, as well as different cancers.

The study, published in PNAS, suggests the drug's effects could also target other types of herpes viruses, since the medication inhibits a key step in the infectious process that is common to them all.

Up until now, only one type of antiviral medicine has proved effective against herpes viruses. Scientists now fear that they may become resistant to these treatments, leaving patients without any therapeutic options. This research is therefore part of a more general effort to come up with alternative drugs to avoid such a scenario.

Blocking virus replication

The team, from the University of Utah, screened different drugs, including Spironolactone, to see if they could block infections differently than current antiviral medication. At the moment, such medication works by inhibiting the virus's ability to replicate DNA, thus stopping its proliferation.

The researchers found that Spironolactone can also stop this proliferation, but through a different mechanism. The drug targets the virus by inhibiting the action of a protein, the SM protein. SM proteins regulate the action of mRNA, the messenger molecules carrying DNA information to the sites of protein synthesis.

Since all herpes viruses depend on SM-like proteins to spread the infection, Spironolactone could be used to develop new therapeutic options that would work against all types of herpes. Lead author Sankar Swaminathan says : "We think it can be developed it into a new class of antiviral drugs to help overcome the problem of drug resistant infections."

No side effects

The fact that the drug is already largely and safely used for other clinical medication means risks for herpes patients could be minimal. Unwanted effects could be avoided, as Swaminathan's team discovered that spironolactone's ability to block viral infections is completely independent from its ability to treat heart failure.

Therefore, the scientists believe spironolactone could be used as a basis to create new antiviral drug, without its properties against heart failure. "We think there is great potential to modify this molecule so that it can work as an antiviral without having undesired side effects," explains Swaminathan.

Such a drug could change the life of millions of people worldwide. The WHO estimates that two third of the world population are affected by the most common herpes virus, HSV-1, which causes cold sores around the mouth. 417 million people aged 15-49 years are infected by HSV-2 which causes genital herpes. As for EBV, the CDC says 90% of adults show traces of past or present infections, although in a majority of cases it never develops into a serious disease.