![cover image](https://wikiwandv2-19431.kxcdn.com/_next/image?url=https://upload.wikimedia.org/wikipedia/commons/thumb/4/42/Theodor_O_Diener.jpg/640px-Theodor_O_Diener.jpg&w=640&q=50)
Viroid
smallest infectious pathogens / From Wikipedia, the free encyclopedia
Viroids are the smallest infectious pathogens known. They consist solely of short strands of circular, single-stranded RNA without protein coats. They are mostly plant pathogens (plant diseases), some of which can cause crop loss.[1]
Viroid | |
---|---|
![]() | |
Virus classification ![]() | |
Informal group: | Subviral agents |
(unranked): | Viroid |
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/4/42/Theodor_O_Diener.jpg/320px-Theodor_O_Diener.jpg)
Viroid genomes are extremely small in size. They are about 80 times smaller than the smallest virus.[2] The human pathogen (causes diseases in humans) hepatitis D virus is a defective RNA virus[3] similar to viroids.[4]
Viroids were the first "sub-viral pathogens" discovered and named by Theodor Otto Diener. He was a plant pathologist at the U.S Department of Agriculture's Research Center in Beltsville, Maryland, in 1971.[5][6] The first viroid to be identified was the Potato spindle tuber viroid (PSTVd). About 33 species have been identified.