The ringspot virus was a big problem for the Hawaiian papaya industry for many years, until the 1980s, when they began to experiment with genetically modified versions that were resistant to the virus. It was the addition of the "viral capsid" protein that created the effect of an immune response.
It wasn't until 1999 that the first commercial papaya crops were grown in Hawaii. These papayas now make up about three-quarters of the total output in the Aloha State. Currently, the United States and Canada both give these transgenic papayas the stamp of approval, while the EU has not yet allowed them.