A team of Australian researchers believe they've cracked the cold case of the cold sore that will lead to new lines of investigation to keep the herpes virus dormant for good.
The herpes simplex virus (HSV) lies dormant in a carrier's nerve cells long after any cold sores - a symptom of the virus - have healed, waiting to erupt again during times of stress.
But now researchers at Canberra's Australian National University have discovered that even in this dormant stage of infection, the key damaging genes of HSV may be actively trying to restart infection.
It's this turning on of these genes and their detection by the immune system that is a key part of the battle within the body to keeping the virus in check, says Professor David Tscharke.
"If the virus was to stay dormant for ever that would be a very good thing because obviously you would not be getting recurrent lesions.
"If people get this infection in their eye it is particularly troublesome because the recurrent infection scars the cornea, so if you have too many occurrences it can cause blindness," Prof Tscharke told AAP.
The hope now is that they can find ways to stop this infection from coming back.
"We have been trying to find or understand this virus for many decades and there hasn't been an awful lot of progress.
"I guess what we're saying is that maybe we've been looking at it the wrong way, so now that we have a new way of looking at trying to keep this virus dormant and maybe this new information will provide new leads," Prof Tscharke said.
HSV-1, which is transmitted by oral-to-oral contact, can also cause genital herpes (HSV-2) through oral sex.
Both infections are lifelong and affect billions of people across the globe. According to the World Health Organisation an estimated 3.7 billion people under age 50 - that represents 67 per cent - have HSV-1.
An estimated 417 million people aged 15-29 worldwide have HSV-2, or genital herpes.
There is currently no cure for the infection only antivirals to help reduce the severity and frequency of symptoms.
Additional research is underway to develop more effective prevention methods against HSV infection, such as vaccines or topical creams.
The ANU study has been published in international journal PLOS Pathogens.
