French marine biologists say they have created a revolutionary “vaccine” that protects oysters from a deadly virus that has wiped out billions of shellfish in successive “plagues” off France and Britain in recent years.

French oyster farmers have lived in fear of Oyster Herpes virus type 1, or OsHV-1, since the deadly variant first struck in 2008, wiping out between seven and eight billion tiny molluscs within the space of a few days.

Contrary to the coronavirus in humans, which is less harmful to the young, OsHV-1 kills off juvenile Pacific cupped oyster “spat” before they are strong enough to protect themselves.

Since 2008, even on “good years”, herpes – an unfortunate moniker given oysters’ reputation as “the food of love” – wipes out 50 to70 per cent of juvenile shellfish, experts say.

It has also become the bane of UK farmers, killing eight million shellfish in Whitstable, Kent in 2010. The virus, which is harmless to people, was also found in an Essex river in 2015.

However, researchers at the French Institute for Research and Exploitation of the Sea (Ifremer), say they have come up with a cure that is 100 per cent effective against the blight and could be a “game changer” for the oyster industry.

Benjamin Morga, a researcher, said: “One cannot speak of a vaccine in the true sense of the word as oysters don’t have antibodies; it is rather a stimulation of its immunity.

“The way we did it was to inactivate the herpes virus and introduce it into the oyster, provoking an immune reaction. Certain genes in the oyster are primed to produce proteins naturally present in the shellfish that kill the virus should it come under attack,” he told the Telegraph.