Papaya ringspot virus

Papaya ringspot virus (PRSV) is a potyvirus that infects several plant species, most notably the papaya (Carica papaya). It can also infect some species of melon from the family Cucurbitaceae and a succulent plant from the family Chenopodiaceae.

The virus is not enveloped; it is rod shaped and is between 760-800 nm long and 12 nm in diameter. It is transmitted between plants by mechanical activities like pruning and by the insect vectors Myzus persicae and Aphis gossypii. In papaya the virus causes mottling and malformation of leaves, ringspots and streaking on fruit, stems and petioles, plants become stunted and produce less fruit.

The virus is known to be present in the Middle East, Africa, South and Central American. It has also been found in China, France, Germany, India, Italy, Mexico, Taiwan, and the USA.

In 1995 American researchers developed a transgenic papaya resistant to the virus, by expressing an antisense copy of a viral coat protein in the plant. It was field tested in Hawaii, where it was shown to be effective against the virus. The virus resistant papaya is now widely used by commercial papaya producers in Hawaii.